Good Trees for Fall Color

Good Trees for Fall Color

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

What are some trees that will grow well in our area and provide consistent fall color?  If you’re looking for a bright red to purple, look for an American sweetgum (Liquidambar styraciflua) tree.  They hold their leaves until late in the fall and provide an excellent display.  Look for selected cultivars, such as `Moraine,’ which has a very bright red fall color.  `Moraine’ also has a relatively fast rate of growth.  Sweetgum prefers an acidic, moist, rich soil and will need some special attention in area landscapes where the soil is very alkaline ... but it’s worth the trouble.  Sweetgums are relatively pest free ... another plus on their side.

The red maple (Acer rubrum) is another colorful autumn tree.  It does very well in area landscapes and tolerates a range of soils and conditions.  Its fall color ranges from yellow to orange to fiery red, depending on the cultivar.  While there are many, many cultivars, `October Glory’ and `Red Sunset,’ are two local favorites.

Other trees that provide spots of red, bronze, purple, or yellow fall color include flowering pear, flowering dogwood, red oak, Norway maple, Japanese maple, gingko, aspen, and birch. If you long for more fall color in this area, plant some of these trees and shrubs and encourage others to plant them too!

Preserving Fall Leaf Colors

Preserving Fall Leaf Colors

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

If only we could capture the beauty of autumn and hold it to our hearts all winter long! One of the spectacular features of fall is the wonderful coloring of tree leaves.  The more curious among us might wonder just how does fall color develop in trees?  It's a story that's been told before, but here it is one more time.

The purpose of plant leaves is to harness the sun's energy to feed the tree. It does this by way of the chloroplasts in leaf cells.  The chloropalsts contain the green plant pigment, chlorophyll.  This pigment enables the leaves to capture the sun's energy to make sugars and oxygen from carbon dioxide and water.  During the growing season the chlorophyll in present in abundant quantities.  As the weather turns cool the fall and the days shorten, the leaves stop producing chlorophyll.  

Some tree and shrub species are genetically capable of taking the carbohydrates left in the leaves and making them into anthocyanins.  These are the red pigments responsible for the reds, pinks, and purples in leaves.  As the chlorophyll begins to break down, the newly formed anthocyanins become apparent.  

Other plants are not genetically capable of making the anthocyanins.  When the chlorophyll breaks down in these plants, the leaves reveal the more stable orange and yellow pigments (carotene and xanthophyll).  

Brilliant oranges come from a mix of anthocyanins along with the carotenes and xanthophylls.  Trees that don't "perform" with remarkable colors lose all their pigmentation at one time and usually over a short span.

What are the weather conditions that favor the best fall color?  Autumn weather that favors good production of soluble carbohydrates in the leaves will lead to more splendid fall coloring.  Dry, sunny, and cool conditions but not lots of heavy frost are best for bringing out the reds, oranges, and bright yellows. 

If plants that are supposed to show spectacular color, don't... then their location or general health may be the problem.  Sunlight is generally needed for development of fall color, especially the reds.  If a plant is shaded, development of fall color will be deficient.  If the plant is experiencing stress, such as drought stress, fall color may be lacking.  A plant that is not cued into the advent of fall because it's still growing vigorously due to heavy watering and fertilization late in the growing season, may also lack brilliant color.

Can you remember pressing brightly colored leaves between sheets of waxed paper to preserve their colors?  It's one of those experiences of life that no one should miss. Here's how you do it. Place autumn‑colored leaves between two layers of wax paper.  Cover with an old towel or cloth rag.  Press the fabric with a warm iron, sealing the wax paper together with the leaf in between.  Cut your leaves out, leaving a narrow margin of wax paper around the leaf edge.

Of course that's the old‑fashioned way of doing things.  You can preserve fall leaves in your microwave oven.  Choose fresh leaves with the brightest colors.  You don't want fallen leaves that have already started to dry. Take separate leaves or small twigs and place them in the oven on top of two pieces of paper toweling.  Cover them with one sheet of paper toweling.

Run the oven for 30 to 180 seconds.  The drier the leaves, the less time they will need.  Observe caution, as you could start a fire in your microwave if they "cook" too long.  Be attentive.  Leaves that curl after removal, have not been dried enough.  Leaves that scorch, have obviously been left in too long.  Let the leaves dry for a day or two and then finish the leaves with a sealant, such as an acrylic craft spray.

You may get even better results if you use the microwave and silica gel for drying.  Place a 1.25 inch layer of floral silica gel in the bottom of a cardboard box.  Place the leaves lying flat.  Leaves should not touch and should be at least 1.25 inches away from the sides of the box.  Cover the leaves with a 1.25-inch layer of gel.  Place the uncovered box in the microwave.  You want the microwave to operate at about 200 to 300 watts so if your microwave has 2‑10 settings operate it at level 4.  If the oven only has three to four settings, it should be set at half.  If your oven has a high to defrost options, set the microwave on defrost.  Estimated drying time is 2.5 minutes if you're using a half pound of gel and about 5 minutes if using two pounds of gel.

Yet another way to preserve the leaves is to submerge them in a solution of glycerin and water. Use a mixture of one part glycerin to two parts water.  Place the mixture in a flat pan, and totally submerge the leaves (in a single layer) in the liquid.  You'll have to weight them down to keep them submerged.  In about two to six days they should have absorbed the liquid and be soft and pliable.  Remove them from the pan and wipe off all the liquid with a soft cloth.  Done correctly, the leaves will remain soft and pliable indefinitely.

So take some time with the children in your life and go out and collect some of the treasures of fall.  It's something they'll remember for the rest of their life...  I know I have.

Fall and Winter Watering

Fall and Winter Watering

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

When irrigation water is turned off and systems blown out in the fall, your landscape plants still need water.  Foggy mornings, heavy frost, and cloudy skies often give a false impression that plants have adequate soil moisture.  Relatively dry air and low or no measurable precipitation lead to dry soils.  This means that even in the fall and winter... trees, shrubs, and lawn grasses need water to avoid drought stress.  This is particularly true during the fall and early winter when there is little or no snow cover... or when there is an extended warm fall.

Fall and winter watering can be crucial to having healthy plants in the landscape.  During the summer we are clued in to water stress by wilting and dropping leaves.  Plants that experience fall and winter drought can’t tell us something is wrong until the next year when they fail to thrive the next year.  Fall and winter drought can lead to root injury or death.  These drought-injured plants may not show symptoms of the problem until the next season or even the next year.  In fact they may leaf out and flower just fine in the spring, relying on stored food reserves.  Once that energy supply runs out plants weaken and start dying back.  Even if a plant isn’t killed outright, it is made more susceptible to insect and disease attack.

This type of “winter” injury seems to be more common than we realize in this area.  For the past several years, we have been losing many of our area birches.  This has been attributed to past winter droughts and cold temperatures without the benefit of insulating snow cover.  Birches are particularly sensitive to fall and winter drought.  Weakened by this, the birch trees that weren’t killed outright have become increasingly susceptible to attack by the bronze birch borer, which attacks and eventually kills weakened birch trees. 

Other shade trees are also susceptible to winter drought damage, especially those with shallow root systems.  This includes Norway maple, silver maple, linden, Colorado blue spruce, Norway spruce, and many other evergreens.  Shrubs are also vulnerable to winter drought damage, especially those growing up close to the house or in a warmer location.  This includes junipers, Oregon grape-holly, and euonymus.

So what’s the answer?  It’s simple.... water the landscape in the plants and the fall.  Yes, it will be work and you’ll have to use your domestic water but, the effort will be worth it when you see that your plants survive and others around you don’t do as well as yours.  I’m not talking about watering plants every day.  .... you’ll probably only have to water a couple of times in the fall to prevent damage. 

The most critical time to water is in the fall just before cold weather hits or during extended warm weather.  It’s interesting to note that not so many years ago, horticulturists thought it was a good practice to insure dormancy by drought stressing plants in the fall and this decreased the chance of winter injury.  Research since then has indicated that the reverse is true... so now we try to insure plants aren’t drought stressed in the fall.  The soil should be kept slightly moist down to a depth of 18 inches for most shrugs and a depth of 18 to 24 inches for trees.  Water only when the air temperature is above freezing and the soil isn’t frozen... which isn’t usually much of a problem during the fall but can be during winter dry spells.  Water early in the day to allow water time to drain away from the bases of plants.  (Frozen water next to the bark can physically damage trees and shrubs.)  Soaker hoses work well for applying the water slowly and where needed.

Since fall and winter watering will be more labor intensive for you, apply the water where it counts the most... in the root zone.  Consider that established trees have roots that go out at least as far as the tree is tall and usually further.  It is in the “dripline” and just beyond where most of the water should be applied.  The “dripline” is an imaginary vertical line that is perpendicular to the longest side branches of the tree and perpendicular to the ground.  Water applied at the tree trunk base is wasted because there are no water absorbing roots there.

Watering recently planted trees and shrubs is a different story.  Their roots don’t go out that far yet.  In this case you will want to water the root ball zone and just beyond.  The aim is to water where the roots are.  This makes sense doesn’t it?

Keep in mind that even if we do get lots of rain during the fall, shrubs and trees close to the house foundation or located under eaves may still need watering.  Located in these areas, they receive little precipitation and they lose more moisture than other plants because of their proximity to the structure and reflected heat from the walls.

New Pesticide for Control of Shade Tree Insects

New Pesticide for Control of Shade Tree Insects

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

There continues to be concern about our dependency on chemicals for pest management in yards, gardens, and agricultural crops.  Chemicals that we have relied upon for years have recently come under scrutiny for one reason or another.  Many of these "old" chemicals have one or more objectionable characteristics, such as they're very hazardous to the applicator due to their extreme toxicity in a concentrated form, they don't break down very quickly in the environment, they pose a threat to groundwater due to their leachability, or they may lead to long term health effects like cancer.

It's been said that, "Necessity if the mother of invention."  This is true when it comes to pesticide chemistry.  With concerns about old pesticides and their chemistry, the pesticide industry has worked hard at formulating new and safer chemicals which will be more environmentally friendly and thereby more acceptable to consumers.  Of course, these new chemicals must also do a good job of controlling the pest... whether it's a weed, insect, or plant disease.

One fairly new chemical on the commercial market is an insecticide known by the trade name of Merit.  Its common chemical name is imidacloprid.  Merit has been quite popular for several years in areas where lawn grubs are a problem.  However, since lawn grubs are not usually a serious problem in this area, you've probably never heard of Merit.  Merit is also labeled for use on trees and shrubs. Local pest control operators have started applying Merit to area landscape trees with fairly good results.

Let's take a look at this new chemical.  Bayer Corporation, who manufactures Merit, indicates that it's a "broad-spectrum insecticide."  This means that it kills a variety of different insects.  The label lists numerous sucking insects and some chewing insects which can be controlled with Merit.  These include aphids, adelgids, elm leaf beetles, lacebugs, leafminers, leafhoppers, pine tip moth larvae, scale insects, and thrips.

Bayer also indicates that Merit is a systemic insecticide which means that it's taken up into the plant sap and moves to different parts of the plant.  Bayer indicates that it can be applied as a foliar spray to the leaves or applied to the soil for root uptake.  They point out that soil application is more efficient and effective for long-term insect control.  

Merit uses "new chemistry" and is very low in toxicity to humans, mammals, birds, and fish.  It's used at extremely low rates and there's no odor or phytotoxicity problems (damage to plants.)  Soil treatment also eliminates the chance of spray drift, reducing the potential exposure of humans and pets to this chemical.  Most beneficial insects are also safe with soil applied Merit.

Merit can be applied to the soil as either a drench or by injection.  Commercial applicators often opt for soil injection because it's the easiest to apply when they have the proper equipment.  Injections can be placed right at the base of the trunk; in a grid pattern below the tree's dripline; or in a circle at the dripline of the tree.  Bayer research indicates that all of these methods of placement are equally effective.  Many commercial pest control applicators choose the base treatment because it's most efficient.  Injections are placed a foot or less away from the base of the tree at a depth of six to twelve inches.  If the soil is dry, it's important to follow the application with adequate irrigation to thoroughly moisten the soil.  The soil in the application area should be kept moist for seven to ten days after treatment.  The number of the recommended injection sites increases with the size of the shrub or tree.

Now here's one of the interesting characteristics of Merit...  it will provide season long control if it's applied in late fall or early spring.  It takes about two to three months after application for it to become fully effective in the control of foliar pests on large trees.  It takes about a month after application on small trees and shrubs to become effective.  With this time lapse between application and full effectiveness, it's obvious that it must be applied prior to the time that the anticipated pests will be at their peak.  Foresight is much better than hindsight when using Merit. Fall application would logically be the best time to treat shade trees for aphid problems. 

Merit is now available to home gardeners so that they can treat their own trees and shrubs.  Merit is living up to it's manufacturer's promises... as long as it's applied early enough to become fully effective... and enough water is available to keep the soil moist for at least a week.  As Merit gains in popularity we'll probably not even miss some of those older chemicals that controlled the same pests, but were not as safe to use or as friendly to the environment.  Necessity made it happen.

Tree Care Fact or Fiction

Tree Care Fact or Fiction

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Fact or Fiction? Newly planted trees should be firmly staked to keep them from falling over in the wind. 

Fiction... for most trees planted by home gardeners.  Trees that were growing in containers or were dug with an adequate size root ball don’t need staking... unless they’re being planted on steep slopes or in windy areas.  However, bare root trees frequently require staking while the roots are becoming established. 

If a tree must be staked for stability, it should be done the right way.  When trees are staked correctly, the staking allows for a swaying movement of the trunk all the way down to the ground.  Improper staking leads to taller trees with thinner trunks, less taper to the trunk, and a smaller root system.  Bad staking can cause physical injury to the bark.  Trees that have been poorly staked with the staking supports left on too long are more likely to break over in the wind after the stakes are removed.

The correct way to stake a tree is to place the stakes as low as possible on the trunk and no higher than 2/3 the height of the tree.  Use flexible materials to tie the tree to the stake. Do not use wire! Insure that the trunk can move back and forth all the way to the ground.  Staking should never be left on any longer than needed.  It should be removed when the tree roots have grown and become established, never leaving it on more than one growing season.

Fact or Fiction?  When pruning large limbs off a tree, it’s important to cover the wound left on the tree with pruning paint or a wound dressing.

Fiction.  Pruning paint can actually deter a tree wound from healing.  It’s preferable for the wound made by the pruning cut to dry out, allowing the cambium at the edge of the wound to produce callus tissue and eventually close over the wound.  Pruning paint or wound dressing has been found to slow or inhibit the process.

Fact or Fiction?  Wounds made to the base of trees by mowers or weed eaters can lead to the death of the tree.

Fact. Damage caused to the base of trees by careless mower operators or weed trimmers is a serious problem that often leads to the death of a tree. The problem isn’t usually caused by a small, one time “oops” wound.  Major wounds that damage more than 50 per cent of the circumference of the tree seriously injure and weaken it, but it’s the repeated small wounds that can be the most deadly.  If these repeated injuries end up “girdling” or encircling the tree at the same point on the trunk, the tree will die. 

You often see problems with “mower blight” or “weed trimmer blight” in commercial landscapes and parks where grass is allowed to grow up to the trunk of a tree.  Repeated hits over time lead to the swollen tissues around the base of the tree where it flares outward.  This swollen tissue is wound tissue that has formed from repeated wounding.  The trees may also be thinning or dying back from the top down as a result of the injury and girdling.

To avoid problems from“mower blight” or “weed trimmer blight”, mulch trees with bark or wood chips. The mulch helps control weeds, decreasing competition for water and nutrients, as well as decreasing the potential of mower or trimmer damage.  Research has shown that wood chip mulch can almost double plant growth the first few years after a tree is planted.  Use coarse textured organic mulches applied in a two to four-inch layer around the base of the tree, preferably the diameter of the planting hole or greater.

However, a layer of mulch greater than four inches deep or mulch placed directly next to the trunk can lead to problems.  Keep the mulch about four to six inches away from base of the trunk and don’t let the mulch become any deeper than four inches.

Fact or Fiction?  You can kill a tree by covering over troublesome tree roots that have “popped up” in the lawn with a layer of topsoil, even if the soil is only a few inches deep.

Fact.  Even a few inches of soil applied over tree roots can lead to serious problems and the gradual death of a tree.  This additional soil reduces the amount of oxygen reaching the roots and essentially suffocates the tree.  The amount of damage caused by filling in over tree roots varies with the type of tree, its age, and its health.  The scope of the damage also varies with the amount and type of fill.  Damage is not immediately evident.  It may only show up months or even several years after filling.

Fact or Fiction ?: The best time for planting a tree is in early spring before it leafs out. 

Fact... and fiction.  Horticulturists seem to disagree about the ideal time for planting trees.  Their recommendations vary from region to region.  The reason for this apparent disagreement seems to stem from regional differences in climate and available soil moisture. 

In some regions of the country, such as Western Washington, natural precipitation and subsequent soil moisture is most plentiful during the late fall and winter.  Because of more moderate conditions during the winter and plentiful soil moisture, root growth is possible ...making fall planting ideal on the west side of the mountains.  In the northeastern part of the country, soils during the winter are cold and root growth is minimal. Early spring planting, once the soil thaws, is best in these areas.

In our region it’s difficult for me to say with certainty whether spring or fall is the best time for planting, but I lean towards fall for planting.  However, trees and shrubs planted in the fall must be provided with adequate soil moisture, especially during mild fall and winter months.  A close second-best time to plant trees and shrubs is in the very early spring. The soil must also be kept moist to provide for root growth.  That’s the problem with fall planting and early spring planting in our region.  The best time for planting seems to be when many gardeners don’t have irrigation water available.  The solution is to water the trees with a hose.  Don’t wait until irrigation water is available.

If at all possible, trees should not be planted in late spring right after the tree has leafed out or during the heat of summer.  “Balled and burlapped” trees (trees dug out of the ground and their root balls are wrapped in burlap) lose 90 to 95 per cent of their roots in the digging process.  That’s a lot of root system that must recover before the high water demands of summer. New tree growth, hot summer temperatures, sunlight, and wind all create higher water demands on the tree.  Trees transplanted too late in the spring or in the summer are not able to reestablish their root systems quickly enough.  The result is drought stressed trees that may not survive.

Trees and Allergies

Trees and Allergies

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Are gardeners, horticulturists and plant breeders the ones to blame for the rise of urban allergies?  Thomas Ogren seems to think that they are largely responsible.  Hay fever or seasonal allergic rhinitis is a big problem in this country with more than 35 million people being affected by airborne plant pollens and molds.  Chronic rhinitis is one of the leading causes of missed work days in this country. Treatment for this problem costs over 6 billion dollars a year and one out of every six doctor’s office visits are allergy related..  Ogren is pointing the finger of blame at people who love and work with plants.  How could such an innocent passion be the cause of all this?

Ogren is a former nursery owner with a Master of Science in Agriculture from Cal Poly University.  About 15 years ago he changed directions and has become an allergy researcher. Ogren seems to think a big part of increasing allergy problems is due to the increased exposure to air-borne plant pollens.  Allergies develop from repeated exposure to specific allergens, with plant pollens being the most common outdoor allergens. So why might plant enthusiasts be responsible?  It’s because they unwittingly changed the tree and shrub community in cities and towns to a predominantly male dominant population.  Yes, plant enthusiasts have been sexist.

Ogren points out that this sexist discrimination began back in 1949 when the USDA Yearbook “Trees”  recommended selecting male trees that didn’t produce litter or seeds.  Since then plant people have encouraged planting male trees and shrubs because of the less mess, lower maintenance characteristics they offer. 

At the time UDSA “Trees” yearbook was published, about fifty per cent of the trees in our cities and towns were female.  Since that time there has been a shift to mostly male, pollen producing trees. Also in the 50's, American elms were the predominant street tree across much of the nation. The elms which are monecious have both female and male flowers on the same tree and are generally insect pollinated.  Because they’re not wind pollinated, the elms caused limited allergy problems for city dwellers. 

Along came a disease, called Dutch Elm Disease, that destroyed the population of elms in most American cities.  That left many cities without trees along their streets.  Knowing the value of trees, urban and rural communities replaced the stately elms with other types of trees.  Regrettably these replacements have turned out to be predominantly male, pollen-producing, wind pollinated species.  Are you starting to see the problem? 

To make things a little clearer let’s talk about sex and pollination.  Some trees are “monecious”, having separate male and female flowers on the same plant. Examples include honey locust,  oak, sweetgum, pine, spruce, and birch. Other trees and shrubs are “dioecious” having female and male flowers on separate plants.   Examples include ash, willow, cedar, juniper, cottonwood, mulberry, box elder, holly, yew, and smoke tree. Yet another type are “perfectly flowered” with flowers being both female and male. Examples include dogwood, crabapple, cherry, redbud, magnolia, flowering pear, plum, and hawthorn. 

From an allergy perspective, perfectly flowered plants don’t cause as many problems.  Their pollen tends to be heavy and sticky.  Pollen is usually transferred from the male to the female parts of the plant by insects.  The dioecious and monecious plants are more likely to cause allergy problems because most are wind pollinated.  For wind pollination to be successful they must produce lots more pollen.  From the pollen standpoint, Ogren feels that dioecious males are worst plants because they only bear pollen and dioecious females are the best because the don’t produce any pollen.

Let’s consider that two-thirds of the pollen from wind pollinated trees and shrubs is distributed within 60 feet of the source and 90 per cent of the pollen within 90 feet. Grasses and herbaceous plant pollen tends to travel only a few yards from the plant.  That means that for most of us the pollen that aggravates our allergies is in the landscape at home, school, or work. That means we can have partial control over the situation by selecting and planting trees, shrubs, and flowers that won’t cause as many allergy problems caused by plant pollens. 

Some communities have already come to the realization that certain pollen producing plants are causing a problem.  Tempe, Arizona and Las Vegas, Nevada have outlawed the planting of olive and mulberry trees because of they’re extremely allergenic.  Las Vegas already has 200,000 male mulberry trees.  These male trees were no doubt planted to avoid the female trees and their very messy fruit. Other communities are banning the planting of Bermuda grass lawns because of the large amounts of pollen they produce. Albuquerque, New Mexico has banned the planting of many male plants trees and shrubs and has ordered the labeling of allergenic plants in nurseries and garden centers.  We will no doubt see more regulations and planting ordinances enacted in the future. 

I’m not sure we need laws and ordinances, as much as we need awareness and encouragement to plant trees, shrubs and flowers that won’t cause as many allergy problems.  However, we need to know which are the “good” plants and which are the “bad” plants.  Ogren developed a trademarked scale called OPALS(TM) or the Ogren Plant Allergy Scale.  With this scale plants are ranked from 1 to 10, with 10 having the greatest potential to cause allergy problems.  Various criteria involving 70 factors are used to rank plants.  The scale has been reviewed by allergists and botanists and judged to be a useful tool. USDA researchers at the Northeastern Research Station in Syracuse, New York have started using OPALS(TM) for its allergy projections in major U.S. urban areas.

How can we possibly use the scale to protect ourselves from allergy attacks?  The answer is to start planting landscape with plants that are on the low end of the OPALS (TM), five or less.  However, this is a major shift in thinking for gardeners, nurserymen, plant breeders, and municipalities. It will take time to create awareness and acceptance. We’ll need to have more tolerance for litter and some “messiness”, but a little extra work may well be worth it to save us from runny noses, watering eyes, and other allergy miseries.

To learn more about OPALS (TM) you might want to pick up Thomas Ogren’s book, Allergy Free Gardening published by Ten Speed Press.  In the book Ogren discusses his theories about the increase of allergies and asthma in this country and he lists thousands of plants with their OPALS (TM) rating.  If you’re an allergy sufferer, you may want to use it as a guide when shopping for garden and landscape plants.

I bet you’re curious about how some plants are ranked on the scale.  Here’s a sample:

Male Ash Trees: 9-10

Female Ash Trees: 1

Male Red Maple: 8-9

Female Red Maple: 1

Male Honeylocust: 7   

Female Honeylocust: 1

Male Junipers: 10       

Female Junipers: 1

Dogwoo d: 5

Flowering Pear: 4

Flowering Plum: 3

Flowering Cherry: 7

Double-flowered Flowering Cherry: 1

Birch: 7

Red Oak: 8

Pine: 4

Spruce: 3

Uncommon Trees to Try

Uncommon Trees to Try

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

It's easy to find Norway maple, red maple, flowering pear, sweetgum, poplar, or sycamore trees in many local landscapes, in our parks or along the city streets.  Many are familiar friends that we know by name, but what about some of the less familiar trees that we don't often find in this area?  Let's take a look at a few you might want to consider if you ever run across them in a nursery.

One interesting tree is the Japanese Pagoda Tree, also known as the Scholar Tree (Sophora japonica).  This is a distinctive tree and should be considered as a specimen shade tree.  It grows to 75 feet tall.  It's has a dense upright crown when young, but becomes spreading and broadly rounded as it matures. It has a moderate rate of grow until it reaches the height of 20 to 30 feet and then it grows very slowly.

One of it's best features is its shiny, bright green compound leaves which turn yellow in the fall.  While the compound leaves are fairly large... 6 to 10 inches in length... they break apart in the fall and don't need raking. The tree is a good one for providing filtered shade.

Another distinctive feature of the Pagoda Tree is its flowers which form in late summer... long after most other flowering trees.  The flowers are wisteria-like hanging clusters of creamy-white, somewhat fragrant blooms. These form 3 to 8 inch pods in the fall.

This tree has few pest and disease problems. Once it becomes established, it's fairly tolerant of heat and drought.  The biggest drawback is the yellow staining that may occur from the fallen pods... so don't plant them near a paved surface.  They also take about eight to ten years before they flower, however the cultivated variety `Regent' tends to flower after about six years.

While the Amur Corktree (Phellodendron amurense) probably wouldn't be considered as lovely as the Pagoda tree, it is a tough tree.  With a medium growth rate, it reaches a height of 30 to 45 feet at maturity with a spread to match.  It has few pests and is tolerant of alkaline soil and drought conditions.

The leaves are a glossy green turning a yellow or bronze in the fall. The flowers are an unremarkable yellow-green.  The most attractive features of the Corktree are its overall texture and its bark.  Its short trunk, twisted limbs, stout twigs, and large compound leaves give it an overall coarse, rugged appearance.  As the tree matures the corky bark becomes ridged and furrowed, creating an attractive and interesting pattern. This broad spreading tree should be considered, but only for large lots and park-type areas.

The Katsura Tree (Cercidiphyllum japonicum) should be deemed a great tree on its beautiful fall color alone.  It is a tree though that will need more pampering in our area than the other trees mentioned so far.  The Katsura tree grows to a mature height of 40 to 60 feet with a medium rate of growth.  Its crown is full and dense, changing from a pyramidal form when young to a more spreading form at maturity.  However, some trees maintain their upright form into maturity.

The delicate, heart-shaped leaves are the best feature of the tree.  They emerge in the spring with a reddish-purple color, changing to a dark blue-green in the summer, and then to an unmatched apricot-orange in the fall. 

In other areas this tree does fine in full sun, but in our area it will need some protection from hot sun and dry winds. It can also have problems with sunburn on the bark.  It prefers a moist, well-drained soil which is high in organic matter.  This tree doesn't like drought and should be watered carefully to avoid water stress in the hot periods of summer.   Mulch with an organic mulch, such as compost or shredded bark.  Protect the bark of young trees from full sun.  It has few pest problems. 

If you are looking for a magnificent small tree you might want to weigh the merits of Japanese Stewartia (Stewartia pseudocamellia). Here's a tree that grows from 20 to 40 feet in height at maturity and has a pyramidal to upright-oval shape.  As the Latin name implies, the flowers look like little camellias.  These white flowers with their gold-orange centers are produced in late summer over a fairly long span. 

The leaves are a dark green in the summer turning to various shades of deep red and purple in the fall.  The sinewy bark is another desirable feature of the tree.  As the tree matures, the bark flakes off in patches creating an interesting pattern of cream and tan.

This tree doesn't seem to have a lot of pest problems, but it also needs pampering in our area.  It prefers an acid, moist soil which is high in organic matter.  It should be protected from hot sun and wind.  Be sure to mulch with organic mulch.

Finally, the Chinese or Lacebark Elm (Ulmus parvifolia)is a good, tough medium-sized tree that will most likely be admired for its unusual bark.  Don't confuse this with the weedy Siberian elm (Ulmus pumila) which pops up here and there of its own accord.  The true Chinese or Lacebark elm is much different and much better.  First of all, it’s resistant to elm leaf beetle and Dutch elm disease.  It grows to a height of 40 to 50 feet with a medium to fast rate of growth.  The tree is tolerant of alkaline and poor soils.  However, it does prefer moist, well-drained soil.

The small leaves are a shiny dark green. The bark is wonderful... a mottled pattern of gray, green, orange, and brown.  There are a number of good cultivated varieties available. Depending on the cultivated variety, it develops a graceful rounded crown or an upright spreading form.  If you like the vase shape of the American elm, look for `Emerald Vase' an excellent cultivated variety with an upright spreading form.  `Emerald Isle' is another excellent variety with a more rounded type of crown.  Both are highly resistant to the elm leaf beetle and Dutch elm disease.

Ginkgos Are Living Fossils

Ginkgos Are Living Fossils

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Did you know early in the last century petrified Ginkgo biloba (pronounced GINGK-go bi-LO-ba) logs were uncovered near the Columbia River in Central Washington?  It's believed that ginkgo trees once formed large forests in this area ... over 30 million years ago.  They were preserved by sediments and lava flows that occurred in the Central Washington area.

Jack Hampton, Washington State University Master Gardener, was a nut and fruit enthusiast who passed away in 1999.  He was a local expert on nuts.  Hampton said that, "Most people don't recognize ginkgo trees as nut trees, but they are actually the world's oldest cultivated nut.  At present Ginkgo trees probably don't exist anywhere as wild trees, but 150 million years ago, during the Mesozoic era, they enjoyed widespread distribution throughout the northern temperate zone.  At this time there were dinosaurs, marine reptiles, pterodactyls, ammonites, ferns, and gymnosperms (plants with naked seeds not enclosed in a fruit) inhabiting the earth. Mammals, birds, and angiosperms were just beginning to appear. Angiosperms are basically flowering plants (with seeds enclosed in a fruit.)  The ginkgo is the only non-extinct gymnosperm that has seeds that are not produced in a cone.  They are a living fossil!"

There have been many fossils of the characteristic ginkgo leaves found from the Jurassic and Triassic Periods (135-210 million years ago) when dinosaurs roamed the earth.  The ginkgo forests in North America were wiped out long ago by catastrophic geological and environmental activities, such as floods and the ice age.  So how come do we still have living ginkgo tree around today?   The Ginkgo survived the Ice age because the sheets of ice didn't reach parts of southeast China.  Ginkgoes were able to survive the ancient forces of nature and were later cultivated in temple gardens for centuries by Chinese monks.   All the living ginkgoes that are around today are descendants of these Chinese ginkgoes. 

It's easy to identify a ginkgo tree with its unique, fan shaped leaves.  They haven't changed much in 200 million years!  Ginkgo trees are either male or female.  Hampton notes that the "female tree bears a plum-sized fruit that has a disagreeable odor when ripe.  The pulp may also cause an allergic dermatitis and contact with the skin should be avoided." The odor of the fruit has been compared to rancid butter and dog manure, but I think it's much worse.  Watch out if you step on one... they are odoriferous little land mines.    Hampton wonders what types of animals fed on these to spread them throughout the world in prehistoric times...  obviously ones without a refined sense of smell!

Most people try to avoid planting female ginkgo trees so they can avoid getting these attractive yet stinky fruit.  Unfortunately, sometimes they end up with female trees even though they were supposed to be the non-bearing male trees.  Oops!  You will find a few female Ginkgo trees growing in this area and if you are the curious sort you might want to know how to harvest the nuts.  Hampton offers these tips on harvesting Ginkgo nuts, "Gather the ripe fruits using rubber gloves.  Squeeze out the seeds in a bucket of water, wash them thoroughly, and then dry them.  The result will look like a large unsplit pistachio nut.  They are not ready to eat at this point.  To prepare them for eating, first crack them with a pair of pliers.  Then boil them for about ten minutes.  The inner skin (called a pellicle) will fall off leaving a light yellow kernel.   It's this kernel which you eat.  It tastes something like sweet corn.  You may keep these nuts in your refrigerator in plastic bags for a short time, but they are highly perishable."  Hampton noted that the "Chinese have long eaten these white nuts on special occasions, such as weddings and holidays."    He also cautioned that those new to eating Ginkgo nuts observe caution with this new food.  Eat it only in small quantities until you have determined that you have no allergies to the nuts.

If the opportunity to have a living fossil in your own yard intrigues you, you'll be happy to know that you can grow a ginkgo tree quite easily in this area.  Hampton pointed out that ginkgo trees are hardy, adaptable trees that grow in a wide variety of soils and climates.  They are tolerant of drought and urban air pollution. 

As a young tree, a ginkgo has an upright, irregular pyramidal form, and become broader, and more symmetrical with age.  It reaches a height of 50 to 80 feet at maturity. It grows relatively slowly.  Ginkgo trees are remarkably free of pests and disease problems and quite reliably develop wonderful yellow-gold fall color.  They do best if planted in a well-drained, sunny location.  It does take them a while to recuperate after transplanting.

One special thing to remember when you purchase your tree is that you want a male tree.  Remember the ginkgo is dioecious, meaning there are separate sex trees.  You'll have to take the nurseryman's word for it though... as it takes about twenty years before they start bearing nuts.  There are several selected cultivated varieties that you may want to look for in the nursery.  They are 'Autumn Gold' (a male with a broad, spreading form), 'Pendula' (with branches more or less pendulous), 'Shangri-La' (fast growing with compact form), and 'Princeton Sentry' (an upright form, male.)

Trunk Cracks and Wood Rot

Trunk Cracks and Wood Rot

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

Have you ever seen cracks in tree trunks?  Radial separations of bark and wood are usually referred to as frost cracks.  Almost every reference you’ll look at on tree care blame frost cracks on extremes fluctuations of temperature in the winter.  In fact, most sources blame frost cracks on the phenomenon of “southwest winter injury.”  This type of injury is attributed to the bark and wood of trees warming up on the southwest side on a sunny but cold winter day.  The tissue deacclimates, coming out of its complete winter dormancy.  When the sun goes down and the temperature drops rapidly, the tissues can’t reacclimate quickly enough and the water in the tissue freezes, causing cell damage.  The theory has been that sometimes this tissue damage can result in wood and bark cracks.

For many years bark cracks and trunk splits were attributed only to frost.  It wasn’t until the last twenty years, under the guidance of former U.S. Forestry Service scientist and author, Dr. Alex Shigo, that researchers have realized the real cause of split trunks and bark cracks.  Apparently “frost” cracks start from a wound that may have happened much earlier in the tree’s life.  These wounds are believed to be formed at the death of a root or branch.  This wound can create an internal “crack” that develops as a result of stresses from drying, wind, or temperature extremes.  When other pressures occur, such as the thawing and freezing that occurs in the “southwest winter injury” scenario, the internal cracks develop outward.

While the frost leads to a visible crack and open wound, it’s not the real cause of “frost cracks.”  The real cause of the cracks are the death of major roots at planting time; physical injury to roots from construction or soil compaction; wounds created by flush cut pruning; dead limbs resulting from topping cuts, physical injury to the tree trunk, and poor graft unions.

What is the problem with cracks in the tree wood?  Even though callus forms at the edge of the crack and may appear to close it, the wood will never re-knit together.  It’s not like broken bones on humans.  Once those wood fibers are split, they are split forever.  This weakens the mechanical support of the trunk or limbs involved. 

Which came first the chicken or the egg?  It was thought that trunk cracks developed first and then the decay developed in the center due to the opening created by the cracks.  Shigo discovered that the decay is there before the crack, coming from the dead roots, branches, or wounds which instigated the crack.  Additional fungi and insects may attack the tree as a result of the outward crack, but decay organisms are already present before the outward crack develops.

What can be done about split trunks?  Not much really.  One must realize that most of the wood cells of a tree are dead cells.  As I mentioned, they will not “knit” or grow back together.  In the case of most trunk cracks, the internal wood of the tree is already subject to wood decay from fungi.  The tree may function quite well with little effect from the crack or internal decay, since    the vital functions are carried out in the outer few inches of the tree's circumference.  The real concern is for the tree’s structural integrity.  If wood decay becomes substantial, the tree will become a hazard.

Don’t try to paint or seal the split with any type of compound.  They don’t help and they can aggravate the wound.  The best you can do is clean or smooth the edges of the wound with a sharp knife.  Start at one end of the split, smooth around one side of the wound, going no more than one‑half to one inch back from the split bark.  Stop at the other end and do the same procedure on the opposite side of the split.  This aids in callus development.  Sterilize the knife between cuts by dipping for several minutes in a 1:10, bleach:water solution or a 70 percent alcohol solution.

Occasionally “bleeding” or slimy seepage occurs from cracks and wounds.  This is called wetwood or slimeflux.  It is caused by an infection of the wood by a bacterium.  This bacterium feeds on the sugar in the wood and produces a foul-smelling gas and liquid basically through a fermentation process.  The infection can kill some of the bark cambium and can stunt growth but, usually doesn’t kill the tree.

Not all “cracks” are serious cracks that form in the wood.  Some cracks are simply bark splits and are not likely to be fatal to trees, although they will, in some cases, allow entry of disease organisms which can lead to wood decay.  Most of these bark splits are fairly superficial, forming mainly in the outer bark.  Splits occur vertically along the trunk or main branches.  In many cases, bark splits will often close or callus over completely leaving only a slight ridge in the trunk.

Causes of these splits include various environmental factors, such as rapid growth spurts, drought, fluctuating conditions of excessive and deficient, temperature extremes, southwest winter injury, late fall growth, and sun scald.  Trees that are most susceptible to this type of injury are those with thin bark, such as Kwanzan cherry, maple, and certain fruit trees.  Young trees also seem more prone to bark‑splitting than older, established trees.

So the next time you see a bark split or a crack in the trunk of a tree be aware that the real cause of the problem is not frost.  They are reminders that tree care from the time of planting to pruning all contributes to a tree’s health, now and in the future.

Painting Tree Wounds?

Painting Tree Wounds?

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Should pruning cuts and other tree wounds be covered with some kind of paint? No! Wound dressing or pruning paints are not recommended.  Research has shown that they don't prevent wood decay behind the pruning cut and may even increase the amount of wood rot by keeping the environment moist and dark.  It's better to keep the wound open to air and light.  Sometimes pruning paints are applied for cosmetic purposes.  When this is done, they should only be applied in a thin coat.

Aphids Make Trees Sticky

Aphids Make Trees Sticky

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

 “Why are the leaves of my trees shiny and sticky?  My trees are weeping and get everything underneath so sticky, what’s wrong with them?”  As summer progresses, we’re starting to see more insect pest problems bothering trees, shrubs, and other ornamental plants.  One major insect offender is aphids.  Aphids are often a perennial problem on some types of plants.  With trees and shrubs, like maples, ash trees, and roses, it’s a continual battle to keep aphids at reasonable levels.

Knowledge of your adversary can give you a tactical advantage in your yard and garden confrontations.  Aphids are soft-bodied insects which feed on plants by piercing leaves, stems, or twigs and then sucking out plant sap.  They often suck out more sap than they can use and secrete the excess as a sticky waste... called “honeydew.”  Honeydew is mostly sugar and water and isn’t harmful.  This sticky goo, or honeydew, may be eaten by other insects, or a black mold may grow on it.  This black mold, called sooty mold, is not harmful to the plants.

Along with the problem of “sticky trees,” aphid feeding can cause other problems.  Excessive feeding can lead to a loss of plant vigor and retard growth.  Aphids also secrete a saliva into plants while they feed.  In many plants this saliva causes distorted plant growth in the form of curled leaves, swollen nodes, and distorted growth.  Repeated severe annual infestations can lead to plant die-back.

Before trying to manage any insect population that has gone beyond tolerable levels, you need to understand the insect and it’s life cycle.  There are many different types of aphids with varying life cycles.  Entomologists say that there is probably at least one species of aphid that feeds on nearly every type of plant... trees, shrubs, flowers, vegetables, row crops, and weeds!  With so many different species of aphids it’s hard to know the exact life cycles of all of them, especially since aphids seem to have such a complex and strange life cycle.

Aphids can overwinter as eggs or mature adults.  In the spring, the eggs hatch into “Big Mommas” (actually, entomologists call them “stem mothers”) who produce live young without the “disadvantage” of mating.  These daughters also mate asexually, producing even more daughters.  You can see that without the need for mating that aphid populations can build up quite rapidly.  In fact, it has been estimated that one cabbage aphid “Momma” can be responsible for a family of 1,560,000,000,000,000,000,000,000,000 aphids by the end of the season... under ideal conditions. 

If you’re wondering where all these aphids might be hanging around, they’re probably not all still alive.  Aphids take about one week to mature and then most live for only about three weeks.  Many become the dinner for other insects.  If the colony becomes too crowded or the host plant is stressed, winged aphids are produced so they can move out on their own and seek new sources of food. In the fall, some aphid species produce both male and female aphids for the purpose of mating.  After mating the females lay eggs in protected locations, such as in buds or cracks in the tree bark, for overwintering.

Now we know the life cycle, but what about how aphids look?  Identifying the right pest is important.  As mentioned before, aphids are soft-bodied insects.  They come in a variety of colors including green, white, yellow, brown, black, gray, pink, purple, or red.  Some are even covered with a whitish “wooly” or cottony coating.  Aphids are usually found in large groups on plants, often on tender new foliage or the under sides of leaves.  Most aphids don’t move too fast... as you can’t budge them easily once they’ve found a good source of food.  They know a good thing when they taste it!

Now that we know more about how aphids live and grow, let’s talk about when and how to “control” them.  There are some fairly innocuous methods you can try... when and where they’re practical.

1. First look for signs of natural control.  Aphids have a number of natural enemies... ladybird beetles and their larvae, green lacewings, small parasitic wasps, syrphid fly larvae, predacious stink bugs, and assassin bugs.  If you’re able to find evidence that these natural enemies are present and working, don’t do anything unless the aphid population appears to be beyond their control.
2. Dislodge aphids with a fine but forceful spray of water from your hose. Be sure to move the spray back and forth as well as directing it towards the undersides of the leaves.  This will kill some aphids and many will not make it back to the plant.  Repeat this every several days.  This method of control can’t be used effectively on small or tender plants.
3. On some plants you can simply wipe aphids off plant stems or buds.  However, you may want to wear a pair of garden gloves to do this.  Snip off badly infested branch or stem tips.  Avoid fertilizing your plants with too much nitrogen.  Soft, lush growth encouraged by excess nitrogen is exactly the type of growth that aphids thrive upon.
4. Avoid aphid buildup early in the season on woody trees and shrubs by applying dormant oils to plants that have had problems with aphids in the past.  The dormant oil should be applied in early spring when temperatures are above freezing, but before the buds start to show green tissue.  Use according to label directions... of course.
5. If aphids are out of control and an insecticide is warranted, first consider the use of insecticidal soaps.  These are good materials to use because they protect a number of the “good” insects and they are very low in toxicity.  It’s important to get good coverage and to spray both the tops and bottoms of the leaves.  Repeat as needed.  Check product labels to avoid applying to plants sensitive to soaps. Don’t apply to stressed plants.
6. When aphid infestations are so severe that no other method of control is practical, a chemical insecticide may be needed to prevent further plant injury.  There are a number of pesticides labeled for control of aphids on plants.  However, some of these can only be used on ornamental plants because of their systemic action... meaning that they’re absorbed into the plant sap and move within the plant’s vascular system.  Systemics are particularly useful when aphids are protected by the leaves curled with their feeding damage.  Curled leaves protect aphids against contact insecticides.  Some materials are systemic sprays, such as Orthene, which is taken up into the plant sap of treated leaves.  Others, such as Merit or Di-Syston, are applied to the soil and absorbed with water by the roots.  

Root applied systemics are a practical way of treating a large shade tree with severe aphids populations.  They’re also less detrimental to the beneficial insects in the area.  Di-Syston and Merit (imidacloprid) are available to home gardeners.  Other soil applied systemics, such as Cygon, are available only to licenced commercial pest control operators.  Cygon can be used by home gardeners as a spray, but it’s illegal for them to use it as a soil applied drench on shade trees.  Keep in mind that most systemic insecticides are quite toxic to humans and animals.  Some plants may also be injured by the use of certain systemic insecticides.  Carefully read and follow all the label directions when using a systemic insecticide or any other pesticide product.

Aphids can be pesky, but a little knowledge about how they behave and how to safely manage their populations can lead to truce in your yard and garden.

Don't Top Trees

Don't Top Trees

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

Topping has frustrated people who care about trees for overa century. John Davey, noted tree care expert, wrote in his book The Tree Doctor, published in 1907, that topping was “the work of ignorant tree men” and that “Nature does not form those beautiful and health-giving tops of shade trees to be cut to pieces to furnish ‘beer money’ for a lot of tree fools.” He referred to those people topping trees as “ignorant and nefarious frauds.”  Davey must called it pretty much the way it was back in 1907 and that’s the way it still is today.

Topping of trees isn’t just a regional phenomenon, it happens all over the country. Even in1907 Davey was railing against the topping practices of trees that practically denuded Philadelphia and other eastern cities.  Just why is topping so wrong?  The list of reasons is long:

1. Topping starves a tree by reducing the amount of leaf surface and thereby reducing the tree’s ability to manufacture food for root growth, tree health, and tree vigor.
2. Topping leaves stub cut ends of limbs open to attack by fungi and insects. Decay fungi can eventually create a structurally weak and hazardous tree. Topping increases an owner’s liability by creating a potentially hazardous tree.
3. Topping shocks a tree by suddenly exposing shaded limbs to full sun, resulting in scalding and damage to the bark and tissues beneath the bark.
4. Topping leads to a profusion of weakly attached sprouts the become dangerous as they grow larger and heavier with time.
5. Topping leads to increased expenses from repeated follow-up pruning and the cost of eventual tree removal. Topping can also lead to lower property resale values.
6. Topping disfigures a tree and robs the landscape of its natural beauty, form, and character.

Why do people top trees? That’s a question asked by many people care about trees.  In 1997, James R. Fazio and Edwin Krumpe received a grant to study why tree owners allowed their trees to be topped. In the study they went to owners of topped trees and asked them questions in a systematic way to find out the reasons that they topped their trees. They did this study in eastern Washington and northern Idaho.

The results of this study were published in Volume 8, Number 5 of the Arborist News, a publication of the International Society of Arborists in an article written by the same James Fazio, a professor in the Department of Resource Recreation and Tourism at the University of Idaho. Here is what Fazio and Krumpe found:

Who Tops Their Trees? People who topped trees tended to be the older segment of the population, not highly educated, and in the lower economic levels. Most of those approving the topping owned their own homes. One interesting finding was that a large amount of the topping (26 per cent) occurred relatively soon after the property was purchased.

Who Does the Topping? While many blame commercial tree pruners for topping trees, it appears that only about half of the topping is performed by commercial operators. About 43 per cent of the time either the owners, their relatives, or neighbors do the topping. 

Why Do they Top? Fazio confirmed what many of us had suspected, that “fear is the primary motivation for topping. Fifty-seven per cent of the residents worried that their tree was too high.  The safety of their house was the main concern.” Fazio and Krumpe also found that 24 per centtopped their trees because of concerns about storm damage, six per cent because they thought it was something you were supposed to do, and then there were a variety of other reasons. Only two of the 83 people surveyed preferred the appearance of topped trees.

At the conclusion of the article, Fazio offered his opinions on what can be done to put and end to topping.

1. "Tree care companies are part of the problem and a key to the solution.” He points out that in every area it tends to be certain companies that perform the majority of topping. Fazio feels that short of establishing tree pruning ordinances, peer pressure may be the only way to stop companies and individuals who top trees.
2. Legitimate arborists should make a point of advertising their affiliation with the International Society of Arborists, along with establishing and advertising “ a no topping” policy statement.
3. Encourage communities of all sizes to have licensing requirements for commercial tree work. “The basis for this license need not be onerous, simply requiring a publicly stated business address and showing proof of workers compensation and liability insurance would go a long way to protect consumers.” It’s interesting to note that the study also included a survey of commercial operators. In trying to reach some of those listed in the phone book, a number of companies did not list a business address and refused to provide it when contacted. Would you want to hire a company that wouldn’t tell you where they were located?
4. Fazio strongly feels that efforts to educate the public against topping trees should continue. While many of the arborists who responded to the survey felt that topping was declining, it’s still a common practice, especially in rural areas. A number of the companies surveyed still offer topping as one of their services. 

Fazio encourages everyone who cares about trees to wage a personal campaign against topping trees. There is plenty of research that indicates why topping is not good for the health of a tree and why topping is an economic disadvantage in the long run. However, we need to understand the needs of a tree owner. Educational efforts should not only include information about the “evils of topping,” but should also inform tree owners about how to reduce the size of their tree with better methods of pruning.  Fazio has fought his own campaign against topping. He is the editor of the Tree City USA Bulletin “Don’ Top Trees”published by the National Arbor Day Foundation.  It’s Fazio’s hope that by 2007, the centennial of Davey’s Tree Doctor, “we can look back on topping as a thing of the past.”

Lawnmower Blight

Lawnmower Blight

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Watch out for "mower and line trimmer blight" damage to your trees.  This dastardly disease is the result of tissue damage to the trunks of trees from careless mowing techniques and overenthusiastic weed whacking.  The bark of young trees is especially vulnerable to attack because its thin and tender, but older trees with thin, smooth bark are also susceptible.

Lawnmower blight damages the cambium tissue layer that lies right underneath the bark.  It's only a few cells thick.  The cambium is important because it produces the cells, which develop into the conductive tissue in the trunk.  Damage to the cambium results in decreased flow of water and nutrients upward and sugars downward in a tree.  A tree is "girdled" if damage occurs to the tree all the way around the trunk.  Eventual death is the result of girdling.

Too often we carefully plant and tend our trees, but fail to protect them from "lawnmower blight."  Once a tree experiences this type of damage to its trunk, there isn't much you can do.  Cambium tissue cannot be replaced... it doesn’t regenerate and the tree can't heal itself.  The best control is prevention!

The very best way to prevent damage to the trees is to eliminate grass and weeds growing close to the trunk.  Create at least a 12-inch “weed-free-zone” around the trunk of the tree.  This eliminates the need to mow and potentially damage the tree.  (If you use glyphosate or Roundup to eliminate weeds around the trunk of your tree, be sure to keep the chemical off the bark.  Young bark can absorb the chemical and result in damage.)  Edge the “weed-free-zone” with vinyl edging, bricks, or cedar bender board.  Mulch the area with bark or compost.

Keeping the “zone” weed and grass free isn't just aesthetically pleasing; it's also good for your tree. Research has shown that allowing grass to grow over a young tree's root zone will stunt the tree's growth.  This happens because the grass is a good competitor for water and nutrients.  Another reason is that grass exudes chemicals that retard root growth. 

If maintaining a “zone” around the trunk of your trees just isn't going to work, you can cage your trees with wire fencing or heavy plastic netting that is about 12 inches high.  However, you should have at least a three-inch, weed-free-zone right at the trunk base and keep the caging material from direct contact with the trunk.  This three-inch zone is important because otherwise the grass and weeds will grow up inside the cage resulting in an overgrown, unkempt mess.

Some folks use 6-to12-inch long pieces of large, plastic irrigation pipe to protect the trunk of their trees.  They slit the pipe on one side and then they pry it open to slip it over the trunk.  While this might not be the most attractive way to protect the tree, it does the trick of preventing mower blight.

Why Are All the Birches Dying?

Why Are All the Birches Dying?

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Even if you don’t own a birch tree, it would be hard to ignore the fact that so many birches in our area are dying.  There are various factors involved, but the causes involve stress, winter injury, and a devastating insect borer.

Birch trees are generally not well adapted to our region.  They’re better adapted to areas where the summers don’t get quite so hot; where the soils are more acid and have more organic matter; and where there is snow over the roots during the cold parts of winter.  In their native habitat you’re most likely to find them at cooler, higher altitude locations growing close to water.

Birch Tree Roots Need Air

Birch trees have a rather large system that can spread twice the distance of the tree’s height or more!  A mature tree’s root system can be as large as one-third the size of a football field.  Obviously, birches need room to grow and shouldn’t be planted in areas that restrict their growth.  Small planting areas or sites close to sidewalks, driveways, and building foundations should be avoided. 

Compacted soils limit air getting to roots.  When planting birches you need a soil that has not been compacted by construction equipment.  Compacted soils should be “ripped” or deeply cultivated before planting birches.  (Keep in mind that you need to loosen the soil in an area about one-third the size of a football field.)  If the soil becomes compacted after planting due to traffic from people, pets, or vehicles or due to the use of impact sprinklers, aeration is a must.  Aeration will help get air to the roots and keep the trees healthier.

Birch Trees Need Water

Remember, in their native habitat you will most likely find birches associated with a water source... rivers, streams or lakes.  Watering a birch tree just with your lawn irrigation is inadequate.  Birch trees need much more water than the leftovers they receive from lawn watering. This means watering the trees once a week during the hot part of summer and once every two to three weeks during the cooler parts of the growing season.  Watering deeply with a soaker hose placed at the dripline (the perimeter of the branches) is what’s needed.  After watering deeply the soil should be moist to a depth of 18 to 24 inches.  Watering should continue until the end of October.  If the winter remains mild and warm, then it’s also recommended to water at least once a month if the soil becomes dry.

While it would be very hard to mulch the entire root system of a mature tree, young birch trees benefit from mulching the root zone with bark chips or compost.  This helps maintain soil moisture and keeps the roots cooler.

Birch Trees Need It Cool

“Coolness” or mild summer temperatures are not something we can control, but we can avoid planting birches in sites where they will be under additional heat stress.  Don’t plant them on south or west facing slopes.  Don’t plant them where they’re surrounded by paving or asphalt.  Don’t mulch them with stone or rock mulches.  Avoid planting birches where they’ll also be exposed to strong, drying winds.  Shelter them from wind and sun on the north sides of buildings or with other trees.

Is It Decline or Is It Borers?

Too many birch trees in our area are declining and dying back because they’ve experienced considerable stress.  This stress and subsequent decline of the birches has been the result of inadequate or improper watering, compacted soils, and damage to the roots from cold winter and hot summer temperatures.

Identifying Bronze Birch Borer

The weakened state of local birches has made them very vulnerable to attack from the bronze birch borer.  This is a wood boring beetle pest that is decimating many local birches.  The first symptom of bronze birch borer attack is the wilting and dying back of the top portion of the tree.  However, this is pretty much the same symptom that results from the general decline of the tree. 

To determine if the bronze birch borer is at fault, an examination of the main branches and trunk at top of the tree needs to be made.  The bark will be bumpy and ridged from the borer larvae feeding beneath the bark.  Slicing into the area right below the bumpy bark will reveal serpentine trails filled with the dark excrement of the feeding larvae.  Once the feeding larvae mature they pupate and turn into adult beetles.  The adults exit the tree leaving characteristic D-shaped holes in the bark. These holes are sure signs of bronze birch borer activity.

Resistant Varieties

What can be done to control bronze birch borer in our birches?  Well, the very first thing is to plant trees that are more resistant to attack from the borer.  Unfortunately most of the types of birches planted in our area are very susceptible to bronze birch borer attack.  This includes the European white birch (Betula pendula,) Jacquemonti Birch (Betula jacquemontii,) and Young’s weeping birch (Betula pendula ‘Youngii’.)  The River birch (Betula nigra) and the Heritage birch (Betula nigra ‘Heritage’) are probably the most resistant birches available.  Unfortunately, the River birch and Heritage birch don’t have the much-desired white bark.  Instead they have an attractive peeling apricot colored bark. 

The Whitespire senior birch (Betula platyphylla japonica `Whitespire Senior’ is moderately resistant and does have white bark.  However, it’s important to get `Whitespire Senior’ that has been propagated from the original, superior tree in Wisconsin.  Other trees that are simply designated as “Whitespire” may be seedling trees that are probably not resistant to the borer.

Managing Bronze Birch Borer

If you chose to plant a tree that isn’t resistant to bronze birch borer, your next line of defense is to keep the tree as healthy as possible and growing vigorously.  Plant the tree in a suitable location where the soil can be kept cool and moist.  The north or east side of your home is best.  Be sure to water deeply during the growing season, especially during the hot part of summer.  Mulch the roots with shredded bark, wood chips or coarse compost.  Don’t use rock mulches!

Fertilize the tree to maintain vigorous growth if needed.  Use a slow-release tree fertilizer and be careful not to over-fertilize.  Don’t prune birch trees unless there is a very good reason to prune.  When you prune, avoid pruning in late winter or early spring because the sap will bleed.  Absolutely do not prune until July during the growing season because adult female bronze birch borers are attracted to trees with fresh pruning wounds. 

Chemical control of bronze birch borer is difficult.  Pesticide applications are best applied to the bark to prevent reinfestation by adult borers that have already emerged.  By the time a borer attack is evident, chemical pesticides will have limited or no effect on borers feeding under the bark.  To prevent reinfestation the recommended sprays are applied to the bark and the leaves.  These should be applied in late spring and early summer (May through June.) They must be applied with thorough coverage to the bark because the adults lay their eggs under loose bark and inside bark cavities.  Timing is critical to get the adult beetles and the baby larvae before they eat their way back under the bark where they’ll spend the rest of the summer feeding.  In the fall they pupate or transform into a resting stage just underneath the bark for the winter.  In the spring they mature and transform into adults and then emerge... leaving D-shaped holes.

Systemic insecticides applied to the soil for uptake by the roots or injected into the tree usually have no or only limited effectiveness on the borer larvae in the tree.  The systemic insecticides which do provide some control are only effective when the larvae are actively feeding in the summer and early fall.  Spring and fall applications of these systemics is not practical.

If a birch tree has been infested by bronze birch borer, it’s also important to prune out infested wood as soon as possible.  Pruning cuts should be made properly well below the infested area.  Infested wood should be destroyed or disposed of as soon as possible.

Hot Weather and Leaf Scorch on Trees

Hot Weather and Leaf Scorch on Trees

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

It takes longer for trees and shrubs to show signs of distress from lack of water or improper watering practices than other smaller plants in vegetable and flower gardens..  Leaf scorch is a possible sign of water stress.  Mild leaf scorch appears as the yellowing and then browning and drying of the tips and margins of leaves.  More severe scorch appears as the yellowing and then browning of tissues between the main veins of the leaf or large angular blotches of brown tissues between the veins. (In many cases no yellowing occurs at all, tissues just turn brown.) Extremely severe scorch involves the browning and death of entire leaves.

Leaf scorch is a physiological problem related to watering.  The leaves are telling us that they’re losing water at a faster rate than can be replaced by the plant.  Leaf tissues that are furthest from the veins (the margins and areas between the veins) are the first ones affected by the lack of water. Environmental conditions that increase the water demands on a plant tend to increase the severity of leaf scorch.  Hot temperatures, low humidity, high light intensity, and wind all increase the rate of water loss from the leaves.

Sometimes leaf scorch is simply due to a lack of adequate irrigation during the demanding summer weather.  However, anything that interferes with the uptake and transport of water to the leaves can lead to leaf scorch.  Compacted soils; girdling, choking, or underdeveloped root systems; root damage from excavation; and trunk injury from mowers and weed trimmers are often involved. Certain disease and insect problems may also be part of the problem.   Recently transplanted trees with unestablished root systems are frequent victims of leaf scorch.  

Some types of trees and shrubs, such as Japanese maple and flowering dogwood, are not well adapted to hot summers in an arid climate like ours.  To survive and thrive in our region, they do best where they’re protected from excessive heat, afternoon sun, and drying winds.  In more exposed locations or surrounded by reflected heat from buildings and pavement, they will often develop leaf scorch.  They also benefit by having their roots kept cool with a layer of bark mulch. 

Strangely enough, leaf scorch can also be caused by too much water. Saturated soils don’t allow roots to get the air that they need.  Suffocated roots die and the plant can’t take up water... creating the same symptoms that appear if there isn’t enough water.  Saturated soils can lead to fungal and bacterial root rots and eventual death.

If leaf scorch develops on a tree or shrub of yours, try to determine the cause.  Don’t simply start dumping more water on it, assuming that too little water is the problem.  Check the roots and trunks for problems.  Consider all the possible factors that might be involved, but don’t forget to check soil moisture too.

It’s easy at this time of year to be derelict in your watering duties. Contrary to the belief of many, most trees don’t have tap roots and aren’t able to make use of the water in the water table. Most tree and shrub roots that absorb water are located in the top 18 to 24 inches of soil.   Trees growing in our region depend upon us and irrigation water to supply their moisture needs.

During the hot part of summer, trees and large shrubs should be watered with “deep” watering about once a week.  More shallow lawn watering is inadequate to supply their needs. Use a soaker hose to provide this deep watering.  Soaker hoses are made of porous canvas, plastic, or rubber. They allow water to seep out slowly and are useful in watering trees, flowers, vegetables, and shrub beds. Don’tprovide the water at the base of tree trunks where it’s wasted.  Apply water to the area known as the “drip line”, the outer edge of the branch spread.

Special attention should be given to trees and shrubs planted within the last two years.  Make sure they’re getting enough moisture by checking their root balls.  They can’t “tap” into surrounding soil moisture until their roots grow out of the original root ball. It’s important to keep their root zone moist... but not wet.

How much water does a tree need to keep it “happy”. Research has shown that a mature silver maple can lose over 000 gallons of water a day through its leaves, and a mature oak tree can lose over 400 gallons a day.  However, rather than worrying about how many gallons of water to give your tree, you should be checking the soil moisture in the root zone.  Use a spade, shovel, or probe to see if the soil is moist in the top two feet of soil. 

Prevent hot weather stress in your yard and garden by watering the right way!

Watering Trees

Watering Trees

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Proper watering is always important, but it becomes crucial when the temperature hits triple digits and stays there.  If plants are only provided with shallow waterings every day, they’re probably only getting a fraction of what they need.  Let’s look at the water needs of trees.  Large amounts of water evaporate through tree leaves.  This “pulls” water through the plant.  Water is the “vehicle” that nutrients use to enter the plant.  These nutrients are needed for plant functions and growth.  Water is also needed for vital physiological plant processes.  A lack of water means stress and disruption of plant functions.

While humans are supposed to drink at least eighty ounces of water a day and more in hot weather, trees need gallons of water.  A mature silver maple can lose up to 58 gallons of water per hour on a hot summer day!  This translates to over1000 gallons in a twenty four hour period.  Wow! Watering your tree for 10, 15 or 20 minutes a day just isn’t going to give that big old maple the water that it needs.  It’s like getting only a little glass of water after standing outside all day.

To water trees adequately, water should be applied over a longer period of time that will thoroughly moisten the soil to a depth of 18 inches or more.  Water should be applied slowly enough so that it soaks into the soil without running off down the driveway, sidewalk or street.  An excellent way to apply water slowly is with a soaker hose.  Soaker hoses are made of porous canvas, plastic, or rubber.  They allow water to seep out slowly and are useful in watering trees, flowers, vegetables, and shrub beds.

If you have a solid set irrigation system and numerous trees, soaker hoses might not be practical for you.  You’ll need to work with your system’s timer so that you can apply water for a longer period of time in the same location.  You may want to “pulse” the water, applying it several times with “resting” periods between applications to allow the water to soak in.  Check the soil several hours after you water to make sure that it’s moist to a depth of 18 to 24 inches.

It’s important to point out that the tree roots that absorb water are not right next to the trunk of established trees.  Water applied in the tree trunk area is wasted water.  The fine feeder roots that absorb most of the water for the tree are located at and beyond the “dripline.” The “dripline” is the outer edge of the branch spread.   Newly planted trees are an exception to this rule.  The water absorbing roots of recent transplants will generally be in the area of the root ball.  Care should be taken to keep that root ball moist and water may have to be applied close to the trunk to accomplish this task.

What’s the best time of day to water during the hot weather? It’s probably best to water in the very early morning, but irrigation water isn’t always available when you need it.  If you have a choice, water during the cooler part of the day, morning or evening.  If you water during the hottest times of the day, you lose considerable moisture from evaporation before the plants even get a chance to use it.

It would be a good idea to check out all your sprinkler heads and make sure they’re working properly.  During hot weather, a broken or clogged head might mean a stressed tree, a dead garden plant, or a brown patch of lawn.  If you rely on drip systems to water trees and landscape beds, make sure all the emitters are functioning correctly.

Caution: Even though you want to keep your plants supplied with the water they need, you shouldn’t drown them.  Saturated soils can lead to root rot and the eventual death of trees.

Espalier – Two-Dimensional Pruning for Trees and Shrubs

Espalier – Two-Dimensional Pruning for Trees and Shrubs

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Trees and shrubs are part of our three dimensional world.  It takes an adventuresome gardener to turn a three dimensional plant into one with only two dimensions.  Espalier is the art of pruning that involves controlling tree and shrub growth in a single plane... with the support of a building wall, fence, or trellis.  This type of pruning is an ancient art that dates back to Roman times and was later refined by medieval Europeans to save space in the walled gardens around castles, cathedrals, and monasteries.  They were able to reduce the space needed to grow fruit by keeping the growth relatively flat against garden walls... leaving open space for other garden crops. 

Espaliering also proved useful in cooler climates with shorter growing seasons.  By espaliering fruit trees against south and west facing walls, early gardeners found that they could take advantage of the extra heat in these situations, producing fruit in areas where their climate was usually a little too short or too cool to produce fruit.  These south and west facing sites warmed up earlier in the spring and stayed warmer later in the season.

Another advantage to using espalier techniques with fruit trees was the effect espaliering had on the trees.  Espaliered fruit trees usually come into bearing at an earlier age and are generally more productive with deeper fruit color.  This is because of branch angles and the increased light penetration to leaf surfaces that result from the single plane.

The technique of espalier pruning is practiced by some commercial orchardists today because of the early bearing and productiveness of espaliered trees.  Home gardeners and landscapers often practice espalier pruning for its decorative potential.  Using espalier techniques, gardeners can create screens that don’t take up much room and have a softer look than fences or brick walls.  Espaliered plants can also provide decoration for large, monotonous windowless building walls.

Gardeners should take note that espaliering is a technique that takes time and some expense.  You must select the right type of plants and the right site along with making sure you have adequate support for the plant.  Espaliering a tree or shrub involves pruning and training over time to develop and maintain the framework.

Let’s first chat about what types of plants lend themselves well to the art of espalier. Typically you want plants that have long, flexible branches.  Plants with short or stiff branches are hard to train.  You should also consider the mature height of the tree or shrub.  A tree or shrub, whose mature height is much greater than the wall, fence, or structure you plan to train it too, will be unsuitable.  Favored shrubs for espalier include cotoneaster, forsythia, holly, Pfitzer juniper, Kousa dogwood, pyracantha, winged euonymus, flowering quince, star magnolia, and viburnum. Favored trees for espalier include apple, crabapple, and pear.  Fruit trees that bear their fruit on long-lived spurs are the easiest to espalier.  Fruit varieties that have predominantly spur-type growth, such as Red Delicious, Golden Delicious, and Braeburn apple cultivars along with Bartlett pears, work the best.

In selecting a plant, pick a young, vigorous tree or shrub that has a few well-balanced limbs off the main trunk.  Wait until after the plant becomes well established before you perform the extensive pruning needed to start your espalier framework.  In some nurseries you might be able to find plants that already have some initial espalier training. This will make getting started easier.

When planting your tree, be sure to plant it properly to help insure a tree with a healthy root system.  If you’re planting your tree or shrub against a solid wall, the plant should be situated about six to ten inches away from the wall to allow for air circulation behind the plant.

You will need to provide a sturdy support on which to develop your plant’s framework.  This can be done by stringing heavy wire of at least 12 to15 gauge from eye bolts on the fence or wall.  You can also develop your espalier on a free standing trellis.  Just be sure that the trellis is sturdy enough to support the weight of both branches and potential fruit.  When making a trellis for fruit trees, use 4x4 pressure treated posts, sinking the posts two feet into the soil.  Set the posts about ten feet apart, securing the end posts with stakes and guy wires.  With fruit trees you’ll probably want two to three levels of wire with the bottom wire situated about 18 inches from the ground. 

Designing your espalier is the fun part. A well designed and trained espalier is a real work of art.  If you’re doing your first espalier, you should probably start with a simple design. Some of the most common designs are fan-shaped, T-shaped, palmate, pinnate, chevron or V-shaped.  More difficult designs are cordon, basket weave, and candelabra.  Check pruning books in your local library for diagrams of these designs.  With many of these designs, you’ll need to pattern your wire supports accordingly.  If you want something less formal, an asymmetrical informal espalier can be created by allowing the plant to grow and dictate the design.  Training in this case only consists of keeping growth in one plane.

After your tree or shrub is planted and you have its supports in place, you’ll begin its training.  Spread the main branches onto the supports and tie them in place. You need to be careful not to crack or break branches when you bend them into the wanted position.  New growth early in the summer will be more flexible than older branches.

When tying down the branches, use soft string, strips of rags, rubber grafting bands, plant ties, or raffia.  Avoid using wire that can cut into the bark.  Tie the branches to the supports loosely, leaving some extra room for the branch to grow.  Check the ties every three or four months to be sure they aren’t restricting or damaging the branches.  Replace the tie if its hampering growth. 

Branches that aren’t part of the design should be pruned off the spring after planting. Shape the plant every month or so, removing branches or twigs that aren’t in the correct plane of growth.  Training of simple designs may take only two or three years to develop, but more intricate designs will take longer to achieve.

Espalier is a fun way to relieve the monotony of a blank wall or fence. Anyone who has the heart and patience of a gardener as well as the soul of an artist should give it a try. If you’re successful, you’ll have an interesting and attractive landscape accent... if not, you’ll have a really strange and ugly landscape blemish. 

Garden Note: In our region, gardeners should avoid espaliering on south and west facing walls.  Our intense summer sun and heat will be more than most types of plants can endure, plus plants in these types of exposure are more prone to winter injury. Northern exposures may not provide adequate light for flowering and fruiting trees and shrubs. East facing walls are probably the best bet.

Leaf Scorch

Leaf Scorch

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Hot weather or drought conditions sometimes lead to a physiological problem called leaf scorch. Leaf scorch shows up as a browning and drying of the leaf edges. In severe cases the brown areas will extend into the leaf tissue between the main veins. In extreme cases, the entire leaf turns brown.

Leaf scorch is often more severe on the side of the plant where the heat stress was greater, usually the south or southwest sides. Reflected light from light-colored surfaces and heat radiated from cement or asphalt put additional heat stress on plants and can increase the severity of leaf scorch. Rock mulches also absorb and radiate heat causing plant stress.

Leaf scorch is associated with inadequate amounts of water being available for the plant to use, especially during hot weather when plants have higher water demands. However, the cause is not always a matter of heat stress and too little water in the soil. A number of other factors may contribute to the development of leaf scorch. These factors include:

Inadequate or poorly developed root systems due to recent transplanting or poor planting practices.

Girdling roots choking the tree.

Injury to the roots or trunk, especially mower and weed trimmer injury.

Vascular disease.

Root disease, especially root rot.

Interference with water uptake and utilization due to soil compaction, poor penetration of water into the soil, water run off on slopes; and high salts in the soil.

Excess water and saturated soils exclude oxygen from the roots and also interfere with root function and water uptake. The result of too much water can be the same as too little!

Leaf scorch is a sign that a tree is under some sort of stress. When scorch develops on tree leaves, it's important to analyze the cause and then take remedial action to alleviate the stress and keep the tree as healthy as possible.

Plants with Fall Color

The Leaves of Fall

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Falling Leaves

Trees, shrubs, and vines are also amazing in the fall.  They take cues that winter is on its way from the cooling temperatures and shortening days.  Nature has programmed them to avoid cold weather by stopping growth and becoming dormant.  This is a physiological process triggered by hormonal changes in the plant.  Photosynthesis (the production of carbohydrates using the sunlight for energy) stops.  Nutrients from the leaves are moved to the twigs, buds, stems, and roots. 

Eventually, at the base of the leaf stem a layer of cells forms, stopping all movement of water and nutrients in and out of the leaf.  This layer is called the abscission layer and it’s at this point where the leaves break off and fall from the tree.

Unseen are the internal changes in the buds, stems, and roots, which are becoming less susceptible to damage from freezing temperatures.   Sugars increase to lower the freezing point of cell contents and the cell walls become stronger, along with other protective changes.  During the fall as temperatures continue to decline, plants become “acclimated” to cold temperatures until they achieve their maximum winter hardiness in mid-winter. A plant’s maximum potential hardiness is dictated by its genes. In the spring, a tree or shrub will start to de-acclimate and break its dormancy in response to warming temperatures and longer day length.

It’s interesting to note that many trees and shrubs also have a chilling requirement, much like the bulbs.  They will not readily break their dormancy and resume their growth in the spring unless they’re exposed to enough chilling temperatures.  A good example of this is peaches.  Peach trees need from 700 to 1000 hours of temperatures between 32 degrees and 45 degrees.  That’s why it’s hard to grow peaches in very warm climates, because they don’t get enough winter chilling to break dormancy. 

Gardeners may have noticed certain varieties of peaches advertised by mail-order nurseries as “low-chill” varieties.  These require less chilling than the standard varieties used in cooler areas of the country. What happens if there isn’t enough of a winter chill to meet the tree’s requirement?   Leaf development will be delayed and flower structure will be defective, resulting in poor fruit set.

Fall Color

Fall color is another amazing facet of nature that accompanies the onset of the dormancy process.  I grew up in upstate New York and have always been intrigued with the colors of autumn leaves.  I’ve told the story before of why leaves turn such beautiful colors, but it’s worth repeating again.  As the weather turns cool and the abscission layer starts to form, the leaves stop producing chlorophyll and the green color of the leaves disappears.  This reveals the more stable orange and yellow pigments (carotene and xanthophyll).

Some trees and shrubs also exhibit wonderful red colors.  These species are genetically capable of taking the carbohydrates left in the leaves and converting them to anthocyanins. Anthocyanins are red pigments responsible for the reds, pinks, and purples seen in autumn leaves. As the chlorophyll begins to break down, the newly formed anthocyanins become apparent. Brilliant oranges come from a mix of red pigments along with the orange and yellow pigments. Of course there are trees that aren’t very spectacular and lose all their pigmentation at once, turning from green to brown over a short span.

Autumn weather that favors good production of sugars in the leaves will lead to more splendid fall coloring. Dry, sunny, and cool fall weather, but not lots of heavy frost, are best for bringing out the vibrant reds, smashing oranges, and brilliant yellows.

Plants with Fall Color

Trees and shrubs that commonly provide our landscapes with fall color include red maple, Amur maple, Autumn ashes, red oaks, flowering pear, blueberry, sumac, sweetgum, dogwood, burning bush euonymus, Persian parrotia, and viburnums. Bright yellows come from birch, aspen, and gingko.  They are glorious!

A lack of fall color in a species or cultivar that is supposed to provide a good display can be attributed to its location, growing conditions, or general health.  Full sunlight is needed for the best development of fall color, especially the reds. A plants that’s shaded, will probably not develop good fall color. Plants experiencing drought stress or other problems may also be color deficient in the autumn.  An extremely vigorous plant that’s still actively growing in the fall due to late season pruning, fertilization, or excessive watering will also fail to color up nicely.  This is also a clue that the plant is not becoming dormant and acclimated to cold temperatures.  These plants are more likely to sustain winter injury due to freezing temperatures, especially severe cold early in the winter.

Is My Tree Hazardous?

Is My Tree Hazardous?

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent

How do you know when large older trees have become a hazard and should be removed?

There are symptoms that can tip you offthat your tree is a liability that could fall, injuring people or damaging property. Any one or combination of the following symptoms could indicate that your tree is in trouble

Large branches or major limbs are dead.

Large branches and/or the trunk has obvious rotten wood or hollow cavities.

Mushrooms are present at the base of the tree.

Large branches have fallen from the tree and/or there are broken branches hanging in the tree.

The trunk has developed a strong lean.

Large roots have been severed or damaged by construction, such as root excavation, sidewalk repair, or trench digging for utilities.

The soil level over the roots and/or at the base of the trunk has been significantly raised or lowered more than two inches.

Root function has been impaired by installation of pavement or building foundations over the root zone.

The tree has been topped or severely pruned in the past.

Decay and rot is present in old wounds.

Two or more main branches arise from the same point on the tree

If you suspect that you may be at risk from your tree, it would be wise to consult a certified arborist who has had training in hazard tree assessment.  The arborist can analyze your tree’s situation and recommend the best course of action.  This may include removal of the tree, pruning the tree, cabling and bracing the tree, or removal of possible targets should the tree fail.