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.

Scale Insects

Scale Insects

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

Scale insects are positively insidious. As female scale insects mature, they settle down to feed on a plant, hiding beneath a convex shell-like scale covering.  The female scales never move again.  Concealed beneath the armor-like scale, they often go unnoticed because they don’t move and they don’t look much like insects.

Damage

You might wonder what damage is caused to plants by these sneaky little creatures.  Scales feed by sucking sap from plants.  While a few scales won’t harm a plant, large numbers weaken it.  A heavy scale infestation can make a plant more prone to damage from drought or severe temperatures and make it more susceptible to attack from other insects.  Heavy scale infestations can also lead to the death of branches and limbs or possibly an entire plant.  Some species of scale inject a toxin into a plant as they feed, causing even greater damage. 

Certain types of scale suck out more plant sap than they can use.  They expel the excess sap as a mixture of liquid and sugar called “honeydew”.  The sticky honeydew is not harmful, but it can serve as a food source for the “sooty mold” fungus.  Sooty mold is a black fungus that lives on the secreted honeydew, coating leaves or needles and detracting from a plant’s appearance.

Life Cycle

If the adult females don’t move once they start feeding, one might wonder just how they spread from plant to plant.  Before we can answer that question, let’s take a look at the life cycle of scale insects. Most scale insects start their life as eggs.  These eggs hatch and become immature scales, also known as nymphs.  These immature scales are mobile and referred to as “crawlers”.  The crawlers have six legs and walk around looking for a place to feed on the new plant growth. 

When they are ready to settle down and feed, the crawlers molt and begin forming the scale over their bodies.  They produce this scale covering from waxy filaments and feces.  The shape, color, and size of the scale are distinctive for each species of scale.  The scale covering provides protection from being eaten by other insects... and also from being killed by insecticide sprays.

Once the female scales have settled down to feed and secreted the scale covering over their backs, most species lose the use of their legs.  Male scales are different.  They develop under thin scales and emerge as winged forms.  Their only purpose in life is to mate.  They have no functional mouthparts and can’t feed.  After they mate, the males disappear.  The females then produce eggs (some species produce live nymphs) under their scale covering or in some type of cottony material... and thus the cycle of lives begins again.  Most species of scale that attack outdoor trees and shrubs in our region have only one generation a year.  However, scale insects found on indoor and greenhouse plants can produce several generations a year. 

It is in the crawler stage that scales move from plant to plant, but the tiny crawlers can’t fly and aren’t able to crawl or walk to different plants.  They are moved about in different ways. Their mode of transportation can be the wind, other insects, birds, animals, or even man.

Managing a Scale Infestations

Managing a scale infestation is not an easy task.  Because of their sneaky nature, scale populations tend to build up to large numbers before they’re noticed.  It’s also especially difficult to control these insects because their scale protects them from most insecticides.  Some scales can be controlled with dormant oils applied in late winter.  The oils work by suffocation.  However, it’s in the unprotected crawler stage that scales are most vulnerable to control with insecticide applications.  The problem is that the crawlers are so small it’s difficult to detect their presence and there is a relatively short time before they start covering themselves with a scale. 

A magnifying glass or hand lens will assist you in seeing them.  You can also trap crawlers with double-sided sticky tape wrapped around twigs and branches.  About the time when the crawlers are expected to emerge, place the tape near adult scales and trap the crawlers as they move out to feed on new growth. You may need to renew the tape from time to time, when it loses its stickiness.  Keep an eye on the tape and apply the appropriate sprays when they emerge. 

Scale Insects Troublesome to Trees & Shrubs in Our Region

Pine Needle Scale: This scale is a often problem on stressed pines, especially older trees or those located in dusty areas.  Pine needle scale is white, pear-shaped and about 1/8 inch long.  Its feeding weakens and slows growth.  Pine needle scale can be controlled with dormant oil applied in the spring before new growth begins and with sprays at the crawler stage about April.

Spruce Bud Scale: More and more of this sneaky scale is showing up in local spruces.  It’s often found on the lower branches of spruce trees, but it’s not easily noticed because the scales resemble spruce buds and are located at the base of new twig growth.  Gardeners sometime notice the excessive amounts of honeydew produced by this scale; the bees and wasps attracted to this copious sweet residue; or the sooty mold growing on the honeydew.  However, it may not be noticed until dieback starts occurring.  Spruce bud scale can be controlled with delayed dormant oil in the spring and with sprays when the crawlers appear about June. (Be aware that oil sprays will turn a “blue” spruce to green.)

Juniper Scale: Here’s a little round scale that feeds on the needles of juniper, arborvitae, chamaecyparis, cypress, and red cedar, but it’s most often seen on juniper in this region.  The scale is off-white with a central yellow dot. It tends to be a problem on older, less vigorous junipers.  It can be controlled with dormant oil in late March to early April before new growth begins and with sprays when the crawlers appear about June.

San Jose Scale: This is also a very small scale (1/16 inch in diameter) round scale.  It attacks a wide variety of hosts including apple, cherry, pear, poplar, willow, maple, birch, and many other deciduous trees and shrubs.  It’s black and tends to blend in with the bark of many trees and shrubs. 

This is a common problem on fruit trees and is moved about by the wind, birds, and humans.  Predators sometimes keep small populations of San Jose scale under control, but rampant infestations can be quite damaging.  Control can be achieved with late winter dormant oil and with sprays when the crawlers appear in June and again in September.

Other types of scale sometimes found in this region include cottony maple scale on maples, oystershell scale on various deciduous trees and shrubs, elm scale on elm, and hemlock scale on spruce.

If you should notice some scale on one of your trees and shrubs, don’t panic. Many scale infestations are kept under control by natural enemies.  Sprays may not be warranted if predators or parasites have kept the population in check.  There are also cultural controls that gardeners can employ to assist with prevention and management.  First and foremost, keep your plants happy and healthy.  A tree or shrub that’s growing vigorously and not stressed will be less prone to attack.

Trees With Yellow Leaves That Should be Green

Trees With Yellow Leaves That Should be Green

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

The leaves of most trees should be green, but sometimes in the Mid-Columbia region, tree leaves turn from green to yellow.  It’s a problem called chlorosis.  Chlorosis is an abiotic (not caused by a living organism such as a fungus or virus) disease.  It’s characterized by the greenish-yellow to yellow leaves.

Much of the chlorosis seen in our area on trees is actually iron chlorosis or chlorosis caused by a lack of iron in the plant tissues.  Iron is needed for the formation of chlorophyll, the green pigment in leaves.  Without the green pigment that allows a plant to utilize sunlight for production of food and energy, the plant will die. 

Plants with iron chlorosis first turn yellow-green to yellow between the veins, with the veins remaining a darker green.  With more severe chorosis the leaves become pale yellow and develop brown spots between the main veins.  Leaf margins may also turn brown with the leaves later drying up and falling off.  Tree growth slows to a stop and dieback of branches can occur when iron chlorosis is extremely severe.

Iron chlorosis is quite common in our area because we tend to have alkaline soil, those are soils with a high pH, often over 8.0.  While our soils actually contain adequate amounts of mineral iron, its in a chemical form unavailable to the plants due to the high pH of the soil.  The yellowing or chlorosis can involve the entire tree, or may be restricted to one side or even just one branch.  Within the same yard, there may also be perfectly healthy green trees growing right next to ones with iron chlorosis.

Certain types of trees and shrubs are more prone to iron chlorosis than others because they are more sensitive to high pH soils.  Those trees most likely to show symptoms of iron chlorosis include Pin Oak, Flowering Dogwood, Sweet Gum, Silver Maple, Tulip Tree, Magnolia, Catalpa, White Oak, Holly, and White Pine.  Acid-loving shrubs, like azalea, blueberry and rhododendron, are also prone to iron chlorosis.  These types of trees and shrubs should be avoided when planting in soils where pH is extremely high.

While it’s common to encounter highly alkaline, calcareous soils in our region, a high pH is not the only cause of iron chlorosis.  First of all, it may not even be iron chlorosis.  Chlorosis can be confused with similar symptoms expressed by mineral deficiencies such as magnesium, manganese or boron.

Cultural factors can also lead to symptoms of chlorosis.  Overwatering is probably the most common cause of chlorosis, in fact iron chlorosis can be induced if soils are kept excessively wet as a result of overwatering, compacted soils, or poor drainage.  I frequently see tree and shrubs that have developed “lime-induced chlorosis” as a result of overwatering. 

Chlorosis can also be the result of root damage, girdling roots, or trunk damage from mowers and weed eaters.  This is because root restriction, root injury and trunk injury all impair the plant’s ability to take up and transport soil nutrients.  Chlorosis can also develop in extremely dry soil situations because mineral nutrients must be in solution for a tree to be able to absorb them from the soil.  In dry soils they can’t absorb the nutrients.  I commonly see chlorosis on many silver maple trees in situations where half of the root zone or more is located in an area that isn’t irrigated regularly, such as a dry lot, a gravel driveway, or a ditch bank area.

What can you do about chlorosis?  If the cause is excessively wet soils, adjust the watering so the soil doesn’t remain saturated for any length of time.  You will still need to water the tree adequately so it doesn’t undergo drought stress.  Watering should be done slowly enough to moisten the soil to a depth of at least 18 to 24 inches without saturating the soil.  If the soil is compacted, aeration may help the water penetrate the soil more quickly.  If the soil is too dry, the remedy is simple... water regularly to maintain moist soil to a depth of 18 to 24 inches in the entire root zone of the tree.

If watering or compacted soils doesn’t seem to be the problem, check for trunk or root problems.  Look for trunk injury from physical wounds to the base of the tree from mowers or weedeaters.  See if the bark on the southwest side of the tree has been damaged from winter injury.  Check for girdling roots, constricted roots, or damage to the root system.  When possible, these problems should be corrected.  In some cases the tissue damage may not be able to be corrected and the tree may eventually succumb to its injuries.

Finally, correcting iron chlorosis in alkaline soils isn’t an easy task.  Before you do anything, it’s a good idea to have a soil test performed to find out the alkalinity of your soil.  Once you have determined that your soil truly is alkaline, there are several approaches you can take to attempt to correct iron chlorosis.

One of the simplest approaches is to acidify the soil.  This is most easily achieved by adding sulfur to the soil prior to planting, but acidification is a slow process and pH change will be slow.  To acidify the soil you should add sulfur to the soil, prior to planting.  The easiest sulfur to use is prilled sulfur.  This should be applied at the rate of 25 pounds per 1000 square feet of landscape bed and mixed well with the soil to a depth of 18 to 24 inches.  If trees and shrubs are already established you will need to apply acidifying fertilizers, such as ammonium sulfate.

Another method of correcting iron chlorosis is the application of iron chelates to the soil.  Chelated iron is less affected by soil pH and more readily available to plant.  Iron chelates must be placed in the root zone by drilling holes in the soil or working it into the soil. 

Iron chelates in soluble form or iron sulfate can also be applied to plants through a spray to the leaves.  These foliar sprays often result in a quick “greening” of the leaves, but these effects are generally temporary.  New growth that develops after application will still be chlorotic.

There are also methods available for injecting iron right into trunk tissues with implants or injections, but these cause wounds to the tree trunk it’s not advisable to use them in most situations.

So if your trees are turning yellow, determine the cause and take action.  Keep you thumb and your trees green. 

Buying Quality Trees for Planting in Your Landscape

Buying Quality Trees for Planting in Your Landscape

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Before buying a tree to plant in your landscape, make sure it’s a healthy, high-quality plant.  Whether you shop for your trees and shrubs at a local nursery or at a discount store, you should keep in mind that the plant is not only an investment of money, but also of time.  Don’t waste your time or money on a plant that will not grow well or will become a liability with time.

Some bargains aren’t really a bargain.  That’s why the International Society of Arboriculture advises, “When you buy a high quality tree, plant it correctly, and treat it properly, you and your tree will benefit greatly in many ways for many years.  When you buy a low quality tree, you and your tree will have many costly problems even if you take great care in planting and maintenance.” The International Society of Arboriculture, or “ISA” for short, is a non-profit organization supporting tree care research and dedicated to the care and preservation of shade and ornamental trees.

So what determines if a tree is high quality or low quality? It’s the condition of the root system, trunk, and framework of branches.  A high quality tree is one with an adequate root system for the tree.  The container should be large enough to accommodate the roots without circling roots forming on the outside of the root ball.  Roots that are circling, kinked, or entwined will continue to grow that way.  This usually leads to future problems when the roots eventually choke or “girdle” each other as they grow.  A few circling roots can be cut with a sharp knife and loosened, but low quality plants with a tight mass of circling woody roots should be avoided.

If a root ball is dug and wrapped in burlap (balled and burlapped) there should be enough of a root system to support the tree.  A rule of thumb used in the nursery industry indicates that the diameter of the root ball should be at least ten to twelve times the diameter of the trunk, as measured six inches above the trunk flare.  The “flare” is the area at the base of the tree trunk that curves outward.  It’s where the roots meet the trunk.  When purchasing a balled and burlapped tree, you should be able to see the flare on the trunk and the top of the root ball should be flat, not mounded and covered with bark.

After you get the tree situated in the planting hole, with the top of the root ball at the same level as it was growing in the nursery, you’ll want to cut all the twine off the ball and carefully pull back the burlap.  Remove the burlap by cutting, being careful not to disturb the soil ball surrounding the roots.   A plant with many major roots crushed, cut, or torn is poor quality.  This will greatly affect the tree’s ability to grow.   A plant is also low quality if it lacks enough roots to help hold the root ball together.  This type of tree will have severely restricted growth too.  However, even a high quality plant may have a few damaged major roots.  Use sharp pruning shears to make clean cuts on the injured roots.

A quality tree will also have a trunk free of wounds that are the result of poor pruning cuts or physical injuries to the bark.  ISA warns that there are often injuries or problems concealed by trunk wraps.  “Never buy a tree without thoroughly checking the trunk.”  Problems include poor pruning cuts that leave stubs that won’t “heal.” These can lead to disease and structural defects.  Older pruning cuts should show a ring of callus tissue that has covered the area of the cut.  These cuts are made just outside what is called the branch collar.  If branches are removed with flush cuts, the wound won’t cover over as quickly and can lead to cankers, trunk cracks, or wood decay.

Trees should also have a good, strong basic framework of branches.  If the framework hasn’t been well developed in the growing nursery, you won’t be able to correct significant structural defects with pruning.  The branches on a tree should be evenly spaced along the central leader.  According to the ISA, trees that have branches that are “squeezed” together should be avoided.  “Squeezed” branches are where you have two main branches or leaders arising from the same point.  As these leaders grow, they “squeeze” each other.  The older and larger the tree gets, these leaders often split apart.  Squeezed branches can’t easily be corrected by pruning, especially the larger a tree becomes.

You also want branches with strong attachments, ones that aren’t “squeezed” to the trunk.  When the angle of attachment between the branch and the trunk is less than 45 degrees, this is considered a weak attachment prone to cracking and breakage.  If you’re buying a fairly large specimen, examine the branches and look for small cracks that may already have formed at their bases.  A small crack can later develop into a larger one and lead to branch breakage.

Let’s review.  When buying a tree... you should look for a one with an adequate, healthy root ball.  The trunk should be free of defects and the branches should be well placed along the trunk.  Trees can be a significant purchase.  Take the time to inspect the tree you’re buying.  Inspect the trunk for defects and assess the branch placement and attachment.

Inspecting the root ball is trickier.  While I know a horticulturist who recommends removing a tree from its container right in the nursery, most nurseries won’t like you doing this.  You certainly can’t look at the roots of a balled and burlapped plant at the nursery without causing all sorts of problems.  I recommend checking the roots immediately when you get the plant home.  It’s easy to check the roots of a container grown tree or shrub.  However, balled and burlapped specimens should first be situated in the planting hole and ready to be planted before removing the burlap. 

Some nurseries will recommend leaving the burlap on the root ball.  They will not guarantee their plants if you remove the material.  However, Mid-Columbia Community Forestry Council members have observed too many problems, such as a lack of roots and severe damage to the root system, beneath the burlap to be comfortable with leaving it on.  The burlap also usually doesn’t rot quickly enough in our climate and frequently restricts root and tree growth.  The fact that burlap is often treated with copper to keep it from rotting is also a factor in restricting roots.  Copper retards root growth.  I recommend removing the burlap.

The Use of Imidacloprid for Aphid Control in Trees

The Use of Imidacloprid for Aphid Control in Trees

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

Late winter is a good time to apply imidacloprid to shade trees for control of aphids in the coming season.  Imidacloprid, know commercially as Merit, is available to home gardeners under the name of ABayer Advanced Garden Tree & Shrub Insect Control Concentrate@.  It=s a liquid material that you mix with water in a watering can or bucket and then apply it to the soil at the base of the tree trunk.  It=s taken up by the tree and transported to the leaf tissues where it controls a variety of sucking insects, especially aphids. The amount applied is based on the circumference of the trunk at chest height. 

It takes a while for the chemical to reach the tops of tall trees... so late winter is a great time to apply the imidacloprid so it will be available when the leaves bud out and the early aphids start feeding.  The product is quite expensive and you may have sticker shock after you determine the amount you=ll need for larger trees, but it provides 12 months of control.  It=s also more environmentally sound, eliminating the difficulty of spraying the tops tall trees and removing the possibility of spray drift.  Beneficial insects are also protected by this method of application. 

Imidacloprid is also a good material for season long aphid control in roses.  However, the ABayer Advanced Garden 2 in 1 Systemic Rose and Flower Care@ contains fertilizer and a different systemic, disulfoton, that will only be effective for six weeks or less. It=s applied as a granular to the soil.  For season long aphid control on roses, use imidacloprid applied to the soil.  Just keep in mind that

Control Options for Trees with Sycamore Blight

Control Options for Trees with Sycamore Blight

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

Living in Prosser and working in the Tri-Cities, I have often been able to notice a distinct difference in the climates of each area.  This spring the disparity between the two has become very evident because of a disease problem showing up on sycamore trees. The sycamores in the Prosser and Grandview area have been hit hard by sycamore anthracnose, also known as sycamore blight.  It=s a fungus disease that attacks sycamore buds, shoots, twigs, and leaves. 

Our native sycamores, the western sycamore (Plantanus racemosa) and the American plane tree (Plantanus occidentalis), are very susceptible to sycamore anthracnose, a fungus disease common in this region.  The Oriental plane tree (Plantanus orientalis) and the original (not seedling offspring) London plane tree (Plantanus acerifolia) are more resistant, but not immune.  Resistant cloned cultivars include >Bloodgood=, >Columbia=, and >Liberty=.

This fungus attacks new tissues when they begin to emerge in the spring.  Infection is most severe when the weather is wet and cool with temperatures below 55 degrees.  Depending on the timing of the infection, the fungus may infect and kill expanding bud, shoot, and leaf tissues before they fully develop or it can attack leaves later after they=ve expanded.  On leaves, the fungus creates brown lesions that form along the midrib and main veins of the leaf. 

Cultural Control

Cultural control of the disease consists of raking and destroying fallen leaves and twigs along with keeping the tree adequately watered and fertilized.  On smaller trees it=s recommended to prune out and destroy infected twigs and branches.  Cankers on these infected branches provide spores for future anthracnose infections.  However, removal of cankers by pruning is impractical on large, older trees.

Fungicide Applications

Fungicides to prevent infection can be applied, but these are sprayed onto the tree when the buds begin to swell and the bud caps first start to break.  They are applied again 10 days after the first spray. Timing and good coverage over the entire tree is critical in getting control... something that=s very difficult with big trees.  

Injections for Control

One other control option is available.  This is an injection of a systemic fungicide into the tree.  This is done by drilling small holes into the trunk or root collar of a tree and injecting the material into the tree.  The fungicide is carried through the water-conducting vessels in the wood to the branches and leaves where it will protect against early season infection.  

To be effective this is usually done for two consecutive years.  Some materials are injected in the fall; other materials require an early spring application.  This procedure should be done only by a professional arborist trained in proper injection techniques.  Repeated use of this method may lead to eventual significant damage and wood rot because of the holes that are drilled into the trunk.

Careful Use of Weed Control Chemicals in the Lawn Protects Trees

Careful Use of Weed Control Chemicals in the Lawn Protects Trees

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

"Weed and Feed" or plain "weed" fighting chemicals can cause serious problems for trees and shrubs.  These materials are generally considered safe to humans, pets, and wildlife, if label directions are closely followed.  However, many weed control chemicals are not as safe to the desirable trees, shrubs, and ornamentals growing in the lawn or in surrounding planting beds.  The problem is not really with the weed killing products, but with us... those applying the products.  We frequently fail to read and fully understand the precautions given on the label.

Many products, especially those containing the active ingredient dicamba, advise against use in the root zone of desirable trees, shrubs, and other ornamental plants.  Damage often occurs when gardeners don't realize just where the root zones of these plants are located. 

Trees and shrubs are not tap-rooted (with a few exceptions). Roots expand laterally out from the trunk where there are larger "pipeline" roots that divide and subdivide, becoming smaller with each division until the very ends where the fine-feeder roots are located. The fine-feeder roots are responsible for absorbing water and nutrients from the soil.  The roots of most trees are found in the top 18 inches of soil, with over 50 per cent of their roots found in the top six inches of soil.  They're situated in this top layer of soil because that's where they can get the air, nutrients, and water they need for growth and survival.

Roots go out much further from the tree trunk than once believed.  It was once thought that most of the fine-feeder roots were located primarily in the drip-line zone. This is the area beneath the reach of a tree's side branches... the place where rain "drips" off a tree.  However, research has revealed that the root systems, especially the fine feeder roots, extend out laterally much further from the trunk.  In fact, tree roots often extend out from the tree trunk as far as the tree is tall... or even further.

Before we apply "weed and feed" or other weed controlling products to our lawns, we should step back and assess where tree, shrub, and ornamental plant roots may extend.  In most cases, it would be best to apply the chemicals only to the patches of lawn with weeds, not to the entire lawn where roots of desirable plants may be located.  If you have a large lawn with lots of trees and shrubs, these spot applications may be annoying, but they're important in protecting your plants from damage.

Of course if you don't have many weeds, it's much healthier for your trees and shrubs to either dig out the weeds by hand or spot treat individual weeds.  It's overkill to repeatedly apply herbicides to your entire lawn when you don't have many weeds.  The very best form of weed control is a healthy, dense lawn.  Proper watering, fertilizing, and mowing go a long way in helping you avoid the use of weed control chemicals... and protecting your trees, shrubs and gardens. 

If you chose to use weed control chemicals on your lawn. here are more precautions you should follow to protect your trees and shrubs:

Calibrate—  If you're applying a "weed and feed" or other weed controlling products, be sure to only apply the right amount. If it's a granular product and you're applying it with a drop spreader, be sure to calibrate your spreader correctly and only apply the amount needed for the square footage of lawn.  If you're applying the material as a liquid spray, you should also check the calibration of your sprayer or applicator.  Damage to desirable plants in the lawn or nearby plants is often due to over-application.

Do Your Math—  Do you know the square area of lawn that you're planning to treat?  Don't guess. Actually measure your lawn area and determine the square footage being treated. If your lawn is not an easy rectangle or square, determine the footage by breaking the area into rectangular, square, triangular, and circular blocks.

When Using a Granular—  Many of the granular materials will direct you to apply them when there is dew on the grass or when the grass is wet from a recent rain or irrigation. This helps the material stick to the grass and work more effectively.  If applied to dry grass, they will be much less effective.  There will also be directions on how long to refrain from watering and mowing, whether the material is applied as a spray or a granular.

Sensitive Plants—  Some plants are particularly sensitive to the application of dicamba and phenoxy (2,4 D, MCPP, and MCPA) herbicides in their roots zone.  Damage may occur even when you closely observe all the label precautions.  Trees and shrubs that are particularly sensitive to damage from either dicamba or phenoxy herbicides or both include apple, birch, box elder, catalpa, dogwood, forsythia, grape, honey locust, Norway maple, redbud, Siberian elm, sycamore, and walnut.  Extreme caution should be employed if you have any of these plants in your yard and you use these weed killing chemicals in your lawns. 

Avoid Drift—  Many broadleaf weed controls are applied to lawns as liquid sprays.  Extreme caution must be utilized to prevent drift to nearby areas.  Don't spray when it's windy.  The lower to the ground the application and the larger the spray droplets, the less likely drift will be a problem.  It's worth repeating...don't spray when it's windy or breezy.

What Weed Is It?  —  Get your weed identified first, BEFORE applying any chemicals for control.  If grassy weeds are the problem in you lawn, the typical "weed and feed" products for controlling broadleaf weed chemicals will not touch them.  If they're perennial grassy weeds, they will have to be spot- treated with a non-selective herbicide, such as Roundup or other glyphosate containing product.

If they're annual grasses, you will need to apply a preemergent herbicide, such as we discussed in a recent column. Effective herbicide applications for both perennial and annual weeds in the lawn depend on the type of grass and the appropriate timing of the application.  Get your weeds positively identified before attempting control.

Picking An Herbicide—  Not every weed is controlled by every herbicide chemical.  Most broadleaf weed control products for home gardeners contain more than one active ingredient.  2,4 D has been a popular ingredient for many years and provides good control of a number of common broadleaf weeds, such as dandelions and plantain.  However, there are other weeds for which it really doesn't do a good job of control.  Mixes of 2,4 D andMCPP or MCPA, are typically utilized.  These broaden the number of common broadleaf weeds the material will control, including chickweed, ground ivy, black medic, and clover. 

Many mixes now also contain dicamba to get at some of the more difficult-to-control weeds, such as bindweed, prostrate spurge, mallow, and oxalis.   Mixes that contain dicamba, 2,4 D, and MCPP are often referred to as "Trimec" when listed on the active ingredients of the label.

There are even tougher weeds, that the Trimec combination sometimes won't control.. A newer material, triclopyr, is now available to home gardeners to use on their lawns for control of some of the toughest lawn weeds, such as oxalis, violets, and spurge.  The only home garden product for use on lawns in Washington that contains triclopyr is Monterey Spurge Power that also contains dicamba and MCPA

Fertilizing

Fertilizing

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

Poor fertilization practices can lead to problems with nitrates finding their way into surface water... streams, lakes, rivers... and into ground water. According to Mary Robson, WSU Area Extension Agent in the greater Seattle area, it’s important to apply fertilizers correctly to both provide needed nutrients to plants and to prevent runoff and leaching.

Robson directs her comments, not to the agricultural producer, but to home gardeners. She points out that at this time of year, many gardeners start thinking about applying fertilizer to their landscape and garden plants. Gardeners should apply fertilizers right before the plant buds break and start to grow. This time for our area would usually be in March and early April.

Trees, shrubs, and perennials plants utilize stored nutrient reserves during the first flush of spring growth. Fertilizer is applied to replace nutrients needed by plants and keep the plants healthy. Keep in mind that fertilizer is not plant “food.” Fertilizer simply provides the nutrients that a plant needs so that it can make its own food using energy from the sun by the process of photosynthesis

The following are tips that Robson offers gardeners regarding environmentally friendly fertilization of landscape and garden plants:

ESTABLISHED TREES & SHRUBS   Not all trees and shrubs will need fertilization. Large established plants will often get along fine with only a spring compost mulch or another organic mulch and no other supplemental fertilizer. What are the signs that a plant is growing well? If the plant develops good leaf color, puts on an average amount of new shoot growth and length per season, and generally appears healthy, fertilizer is probably not be needed.

YOUNG TREES & SHRUBS   A young landscape plant does need spring fertilization. If the garden has newly planted trees and shrubs, installed within the last two to four years, be sure to fertilize these to ensure the best growth possible.  Roots that are just getting established need extra nutrients in their second year.

WHEN TO FERTILIZE   It’s easy to over-fertilize, applying too many nutrients too often by assuming that landscape plants need lots of “plant food.”  Be sure to follow label directions for quantity and don’t add fertilizer to tree and shrub plantings after active spring growth has finished.  This means eliminating fertilizer applications to landscape plants after the middle of summer.  If you apply fertilizer too late in the season, the plant may fail to go into normal fall and winter dormancy and can be harmed by winter freezes.

NEWLY PLANTED TREES & SHRUBS   Robson recommends mulching newly planted trees and shrubs with two to three inches of mulch and then waiting to fertilize six months before applying any fertilizer to the newly installed plant.  This is good advice for the Seattle area.  However, many of our local soils contain so little nitrogen, that fertilization at planting time will greatly benefit plant growth.  Moderate amounts of slow-release fertilizer or tablets added to the planting hole can provide the needed nutrients as soon as the roots start to grow out of the original root ball.  If planting in a landscape or perennial bed, slow-release fertilizer and organic matter should usually be added to the soil when preparing the bed prior to planting.

Fertilizer bags often have confusing labels with different numbers.  Nitrogen is the main nutrient needed for good spring growth of woody plants.  Nitrogen is represented by the first number in the set of numbers on the fertilizer label.  Since that’s the primary nutrient needed by your trees and shrubs, you should look for a fertilizer where that number is larger than the other two numbers that represent the amounts of phosphorus and potassium.  Slow-release formulas are more expensive, but they’re best for your plants because nutrients are released gradually rather than all at one time.  Slow-release fertilizers generally lead to less waste and leaching of nitrogen and promote better plant growth.

If your trees and shrubs are situated in or next to the lawn area, they’re probably getting more than enough fertilizer through your regular lawn fertilization, especially if you aren’t using a slow-release material.  This can explain why you don’t usually need to fertilize these plants!  Yet, it’s important to note that the best times of year to fertilize lawns are not always the best time to fertilize trees and shrubs.  Washington State University Cooperative Extension recommends fertilizing lawns in September, early November, June, and May.

This dichotomy in fertilization times causes us a dilemma.  Should we fertilize the lawn at the right time or fertilize our trees and shrubs at the right time?  Fall fertilization can lead to problems especially when tender plants are fertilized late in the season.  Fall is the best time to fertilize our lawns to keep them healthy and thick enough to keep weeds out.  What should we do?  There may be no good solution.  However, try to avoid applying fall lawn fertilizers to areas above tender trees and shrub roots.  Slow-release fertilizers would help avoid a late flush of growth on woody plants that might be stimulated with a quick-release type of fertilizer.

How much fertilizer should be applied to individual trees and shrubs?  That’s one of those questions that’s hard to answer directly.  The amount of fertilizer needed depends on the size of the plant and the type of fertilizer applied.  To help you determine the amount of fertilizer you should apply to trees and shrubs, Washington State Unversity Cooperative Extension has a handy bulletin, “Fertilizing Landscape Trees and Shrubs EB1034," with the recommended rates and methods of application.  You can purchase one at your local county extension office.

How can you tell if your plants need fertilizer?  Look for plants that aren’t putting on good growth, where leaves are undersized and chlorotic or yellow.  Here again we have another dilemma, because these are also symptoms of other plant problems.  In many cases the symptoms of poor growth and yellow leaves turn out to be a root or soil moisture problem.  If the tree or shrub has trunk injury, root damage, girdling roots, root rot or excessive soil moisture or drought, the symptoms will be pretty much the same.  Fertilizer will not help these plants or solve the problem of poor growth.

How can you tell if this is a root problem or a lack of nutrients?  If most plants in the yard and garden are growing well without any special fertilizer applications, this is a hint that the affected plant has a problem unrelated to soil fertility.  If the problem happened over a fairly short period of time, this is a hint that a root or soil moisture problem is involved.  If you suspect a root problem, you can check it out by examining the base and roots of the plant.  This involves a process of gentle excavation.  Soil moisture in the root zone and irrigation practices should also be reviewed.

Robson wants home gardeners to know that fertilizing landscape plants isn’t just a matter of buying a bag of fertilizer and applying it.  Responsible, caring gardeners should observe the health and stage of growth of the plant first.  “Apply the right amount at the right time!”

Planting Trees Correctly to Ensure Their Success

Planting Trees Correctly to Ensure Their Success

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist

Planting a tree isn’t as simple as digging a hole and sticking it in.  Many trees fail to grow and thrive because they aren’t planted correctly.  To determine just what is the “right” way to plant a tree, let’s look at some of the most common mistakes made when planting a tree or a shrub.

Too Deep

Probably one of the most common reasons for failure in planting trees and shrubs is that the root system is planted too deeply.  Roots need air.  They should always be planted at the same level or slightly above the level that they were growing in the nursery or in their container.  Planting them deeper than this deprives the roots of air and will eventually kill most plants.  Death is not usually a sudden thing.  Trees planted too deep will fail to grow well.  Leaves and new growth will be undersized.  Leaves may develop leaf scorch along the edges or become yellow and drop off the tree.  Keep in mind that trees aren’t tomatoes, most won’t tolerate deep planting.

Planting With Material Around the Root Systems

Any material around the roots... plastic twine, burlap, boxes, paper pots, and plastic pots should be removed at planting time.  Most gardeners don’t have to be told to do this, but you’d be surprised at how many people belatedly find trees and shrubs planted with the roots still in a plastic pot.

Whether it’s a non-degradable material like plastic or a material such as paper which will eventually rot, it should be removed.  Materials like cardboard boxes and pressed paper pots do rot, but they don’t rot quickly enough in our garden soils.  They impede water movement and restrict root growth.

The same holds true for burlap.  Even though burlap seems to rot readily it doesn’t rot as quickly as we would anticipate.  Some burlap is even treated with a copper material to retard decay.  Since copper is toxic to root tissues, the roots won’t grow through the burlap layer even if the burlap has decayed.  In some instances, plastic burlap is used.  That definitely won’t decay any time in the near future.

Dense Root Masses and Encircling Roots

When left growing in containers too long, many trees and shrubs develop cramped root systems, which make it difficult to grow them with success.  For plants to survive and grow, you will need to loosen the roots of those with dense, fibrous root systems.  When roots are dense and matted, cut them with a shovel, spade, or knife.  Make six to eight shallow vertical cuts into the exterior root mass.  Use your fingers or a hand fork to loosen the cut roots and help spread them out.

Another method of remedying problems with dense root masses of container grown plants is to “butterfly” the bottom of the root mass.  Use a shovel or spade to divide the bottom half of the root mass, creating two flaps or “wings.” The “wings” are kept apart by with soil, a stone, or a stick before filling the planting hole with soil.  Make six to eight vertical cuts to the exterior roots in the uncut, top portion of the root mass.

Plants with thicker, woodier roots, often develop encircling roots when grown in a pot too long.  These roots will keep growing in circles, if they aren’t disturbed at planting time.  The roots should be cut and spread as just described above.  With encircling roots the plant eventually chokes itself to death. Circling roots can’t reach out in the soil for water and nutrients needed for healthy growth and the poorly established root system doesn’t perform its anchoring function very well.

Clay Root Balls

Many quality nursery plants sold in this area are dug from nursery fields in the Williamette Valley in Oregon.  Many of these fine plants have one major drawback... the soil in the root ball is a heavy clay.  This clay is very different from local yard and garden soils.  It’s dense and holds onto water very tightly.  When the landscape is watered to accommodate our lighter, more droughty soils, the plant ends up with roots that are constantly too wet because of the clay soil around the roots -- this often leads to root rots.

One can avoid the problem by avoiding the purchase of plants with clay soil or one can try to remedy the situation by gently forking soil away from the root system and exposing the roots.

Creating a Bathtub Effect

Adding organic matter such as peat moss, compost, or mulch to the backfill soil of a planting hole is not a good.  It generally is not helpful and can create a “bathtub” effect.  Water easily enters the coarser soil in the planting hole but drains our slowly because the surrounding soil is more dense.  Again, the roots stay wet for long periods of time and root rots are very likely to develop.

However, when planting an entire landscape bed or border amending the soil with organic matter is a good idea.  Loosening the soil and adding the organic matter fosters good root growth.  Preparing the soil in the entire bed for planting eliminates the bathtub effect that can occur with planting holes.

Compact Soils

In planting sites around new homes and buildings, the soil is often very compacted.  This is especially true on commercial sites where the soil had been compacted with heavy machinery to provide a suitable area for paved parking.  Roots of trees, shrubs, and other plants have a hard time growing in compacted soil.  Water doesn’t move well into and through compacted soil.   There isn’t as much oxygen available to plant roots in a compacted soil.  Because the soil is tight, roots have a hard time penetrating the soil.

The best thing that can be done in a new planting area to relieve soil compaction is to loosen the soil by physically disturbing the soil by deep tilling or digging.

Proper Planting Techniques

1. Dig the hole deep enough to accommodate the root ball.  Keep in mind that the top of the root ball should be level with the soil or slightly above it.  The planting hole should be at least twice the diameter of the root ball.  The wider the hole, the better. Note: Always lift your tree and shrub by the root ball, not by holding onto the trunk. 
2. For balled and burlapped plants, first situate the plant in the hole and then remove all twine, string, or wire from around the root ball and stem.  Cut the burlap away from the root ball, removing as much as possible from the hole. For container-grown plants, cut and loosen roots if needed before placing the root ball in the hole.
3. Add appropriate amounts of slow-release nitrogen fertilizer to the planting hole. Backfill with the native soil you removed from the hole. Do not amend the backfill soil with organic matter. Gently firm the soil around the roots and definitely don’t tamp the soil down around the roots with your feet.
4. Water the plant thoroughly to help settle the soil around the roots.  Mulch the entire root zone area with bark mulch.
5. Keep the soil around the roots moist but not wet and saturated.
6. Prune to remove only the broken branches.  

Chlorosis — Yellow Leaves

Chlorosis — Yellow Leaves

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

Leaves turning yellow is called chlorosis. Chlorosis is an abiotic (not caused by a living organism such as a fungus or virus) disease. It's characterized by greenish-yellow to yellow leaves. What causes chlorosis? The answer isn't easy because the cause is probably not the same in every case... but there are some very likely possibilities.

Much of the chlorosis seen in this region on trees during the summer is actually iron chlorosis or chlorosis caused by a lack of iron in the plant tissues. Iron is needed for the formation of chlorophyll, the green pigment in leaves. Without the green pigment which allows a plant to utilize sunlight for production of food and energy, the plant will eventually die.

Plants with iron chlorosis first turn yellow-green to yellow between the veins, with the veins remaining a darker green. With more severe chlorosis the leaves become pale yellow and develop brown spots between the main veins. Leaf margins may also turn brown with the leaves later drying up and falling off. Tree growth slows to a stop and dieback of branches can occur when iron chlorosis is extreme.

Iron chlorosis is quite common in our area because we tend to have alkaline soil. Alkaline soils are characterized by a pH above 8.0. While our soils actually contain adequate amounts of mineral iron, its in a chemical form unavailable to the plants due to the high pH of the soil. The yellowing or chlorosis can involve the entire tree, or may be restricted to one side or even just one branch. Within the same yard, there may also be perfectly healthy green trees growing right next to ones with iron chlorosis.

Certain types of trees and shrubs are more prone to iron chlorosis than others because they're more sensitive to high pH soils. Those trees most likely to show symptoms of iron chlorosis include pin oak, flowering dogwood, sweet gum, silver maple, tulip tree, magnolia, catalpa, white oak, holly, and white pine. Acid-loving shrubs, like azalea, blueberry and rhododendron, are also prone to iron chlorosis. These types of trees and shrubs should be avoided when planting in soils where the pH is extremely high.

While it's common to encounter highly alkaline, calcareous soils in this region, a high pH is not the only cause of iron chlorosis. First of all, it may not even be iron chlorosis. Chlorosis can be confused with similar symptoms expressed by mineral deficiencies such as magnesium, manganese or boron deficiencies.

Cultural factors can also lead to symptoms of chlorosis. Over watering is probably the most common cause of chlorosis, in fact iron chlorosis can be induced if soils are kept excessively wet as a result of over watering, compacted soils, or poor drainage. Tree and shrubs in this region often develop "lime-induced chlorosis" as a result of over watering.

Chlorosis can also be the result of root damage, girdling roots, or trunk damage from mowers and weed eaters. This is because root restriction, root injury and trunk injury all impair a tree's ability to take up and transport soil nutrients.

Chlorosis can also develop in extremely dry soil situations because mineral nutrients must be in solution for a tree to be able to absorb them from the soil. In dry soils they can't absorb the nutrients. Chlorosis is often seen on large silver maples in situations where half of the root zone or more is located in an area that isn't irrigated regularly, such as a dry lot, a gravel driveway, or a ditch bank area.

What can you do about chlorosis? If the cause is excessively wet soil, adjust the watering so the it doesn't remain saturated for any length of time. You will still need to water the tree adequately so it doesn't undergo drought stress. Watering should be done slowly enough to moisten the soil to a depth of at least 18 to 24 inches without saturating the soil. If the soil is compacted, aeration may help the water penetrate the soil more quickly. If the soil is too dry, the remedy is simple... water regularly to maintain moist soil to a depth of 18 to 24 inches in the entire root zone of the tree.

If watering or compacted soils doesn't seem to be the problem, check for trunk or root problems. Look for trunk injury from physical wounds to the base of the tree from mowers or weed trimmers. See if the bark on the southwest side of the tree has been damaged from winter injury. Check for girdling roots, constricted roots, or damage to the root system. When possible, these problems should be corrected. In some cases the tissue damage can not be corrected and the tree may eventually succumb to its injuries.

Finally, correcting iron chlorosis in alkaline soils isn't an easy task. Before you do anything, it's a good idea to have a soil test to find out the alkalinity of your soil. Once you've determined that your soil is alkaline, there are several approaches you can take in an attempt to correct iron chlorosis.

One of the most simple approaches is to acidify the soil. This is most easily achieved by adding sulfur to the soil prior to planting, but acidification is a slow process and the pH change will be slow. The easiest sulfur to use is prilled sulfur. This should be applied at the rate of 25 pounds per 1000 square feet of landscape bed and mixed thoroughly into the soil to a depth of 18 to 24 inches. If trees and shrubs are already established you will need to apply acidifying fertilizers, such as ammonium sulfate, instead.

Another method of correcting iron chlorosis is the application of iron chelates to the soil. Chelated iron is less affected by soil pH and more readily available to trees. Iron chelates must be placed in the root zone by drilling holes in the soil or working it into the soil.

Iron chelates in soluble form or iron sulfate can also be applied to plants through a spray to the leaves. These foliar sprays often result in a quick "greening" of the leaves, but the effects are temporary. New growth that develops after application will still be chlorotic.

There are also methods available for injecting iron right into trunk tissues with implants or injections, but these cause wounds to the tree trunk and many arborists advise against using them.

So if your trees are turning yellow, determine the cause and take action.

Stopping Wormy Fruit in Cherries and Apples

Stopping Wormy Fruit in Cherries and Apples

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

There seems to be a great deal of confusion about the need for spraying fruit trees to control insects and diseases.  There are a number of pest problems on fruit trees that require frequent and regular chemical applications to keep the trees healthy and producing quality fruit.  When fruit trees are large, this becomes a difficult, costly, and time-consuming responsibility for their owners.  Smaller, dwarf trees are easier to handle, but still require regular attention.  Owning and caring for fruit trees is not a low maintenance endeavor.

One of the major pest problems faced by backyard fruit growers... the cherry fruit fly.  It’s first and foremost on the list because it’s the pest that causes worms in cherry fruit.  The adult of this pest is the cherry fruit fly.  The adult is a fly that begins to emerge from the ground in late may or early June.  The adult fly takes about seven to ten days to fly around and mate.  After mating, the female lays eggs underneath the developing cherry’s skin.  (No hole is visible in the cherry after she lays the egg.) 

The eggs hatch into small larvae, actually maggots, and begin feeding close to the pit. After about five to eleven days, the maggots each make one or two breathing holes in the skin. (These holes are small but visible.)  Several days after making their breathing holes the maggots are fully mature.  They exit the fruit and drop to the ground where they go into their resting pupae stage.  They spend the rest of the year as pupae in the soil until next spring.

While eating one of these maggots (yuk!) won’t hurt you, it’s certainly not appetizing.  An entire load of commercially grown cherries can be rejected if even one larva is found.  Control of the cherry fruit fly is aimed at killing the adult fly before she lays her eggs under the cherry’s skin.  Once they’re under the skin, pesticide sprays are useless in killing the developing maggot.  That’s why it’s so important to spray regularly and get rid of the flies before they have a chance of laying eggs.

To control cherry fruit fly, backyard cherry growers should recommended sprays regularly, every seven to ten days starting about Mother’s Day weekend..  (Remember, you can’t tell by looking at them whether cherries contain maggots or not.) 

If you’re doing a good job of controlling the cherry fruit fly in your yard but you have a neighbor who isn’t, you may still get maggots in your fruit.  That’s because the flies from your neighbors’ trees are capable of coming over to your tree and laying eggs after you spray.  That’s why it’s important for all backyard orchardists to control this pesky fly... as they cause problems to others growing cherries including the many commercial cherry growers in this area.

Let’s move on to worms in apples.  This is a very different insect pest... the adult is a moth.  Worms in apples are the result of codling moths.  The adult moths emerge sometime in May... about 14 to 21 days after the tree was in full bloom and start laying their eggs on leaves and the surface of developing apples and pears. (They also may attack quince, crab apple, hawthorne, and English walnut.)  It takes anywhere from six to twenty days for the eggs hatch into little larvae.

Once they hatch, the codling moth larvae chew their way into the fruit and proceed to eat their way to the center and eat on the seeds.  As they start to mature, they eat their way out of the fruit, usually exiting at the base.  They then find their way to the branches and trunks to spin a cocoon under loose bark or other little hiding places.  They pupate or go into their resting stage in the cocoon.  There are usually two generations of codling moth a year, but there can be three during longer, warmer seasons.

Control of codling moth is aimed at killing the baby larva before it enters the fruit.  Since it chews on the skin of the fruit before entering, pesticides applied to the fruit will kill the larva both through direct contact and through ingestion.  Because there are at least two generations a year, pesticide applications must be made regularly starting soon after adults start laying eggs and continuing through the summer.  Spray apples and pears on a regular basis with the recommended material starting when codling moths are present and laying eggs.  That’s usually two to three weeks after full bloom... usually around Mother’s Day weekend.

Things you should know about controlling cherry fruit flies and codling moths:

1. Dormant oil and dormant fungicide sprays do not control either pest.  They control overwintering insects, such as aphids and scale.
2. Good coverage of the tree with pesticide spray is important. Start at the top of the tree and thoroughly cover the tree just to the point of runoff. Spray the leaves, fruit, limbs, and trunk.
3. Don’t spray when it’s windy.
4. Don’t spray when it’s hot... over 85 degrees Fahrenheit.
5. Avoid wetting the leaves with irrigation sprinklers right after applying the material.

Winterizing Trees and Shrubs

Winterizing Trees and Shrubs

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

Avoiding drought stress with adequate fall irrigation is also important in winterizing your trees and shrubs. Be sure to give your landscape plants a deep watering before your water supply is cut off for the season.  Don’t neglect watering the trees, especially birches, situated in your in the lawn. 

Fall watering is critical for the broadleaf evergreens, such as rhododendrons, and needled evergreens, such as like pines and arborvitae, in your landscape.  They may not be actively growing, but evergreens still lose moisture through their leaves and needles during the winter.  They’re prone to damage from winter drought... another reason to keep a hose and sprinklers handy during the winter months.  Don’t let them go dry, especially during mild winter weather.

Fall fertilization may also give some protection to trees and shrubs against cold winter temperatures.  If you decide to fertilize your plants, place the fertilizer in the root zone area after they have gone dormant, but before the soil in the beds drops below 45 degrees.

Mulching the root zone of trees and shrubs is frequently recommended for weed management and to help reduce the loss of moisture from the soil, but it can also provide some insulation to tender root systems. This is particularly important for plants that are only “borderline” hardy in this region, as well as for young or recently planted trees and shrubs. 

Loose mulches can be applied to the root zone to provide some insulation from cold temperatures and to moderate the effects of freezing and thawing.  Apply a several inch layer of a mulch material that allows good air and water movement.  Use mulches like shredded bark, pine needles, or coarse compost.  Keep any mulch several inches away from the trunk of the tree or shrub to discourage mice and to avoid problems from excess moisture close to the base of the plant.

Trunks of young or recently transplanted trees can be protected against splits by shading the south and west sides of the trunk.  Some gardeners shade the trunk of their trees with a commercial bark wrap or they simply use a board on the sunny sides.  The shading or wrap keeps sunlight off the trunk, preventing the bark from warming up too much on a cold winter day and reducing temperatures fluctuations that can lead to trunk or bark splitting.

Aphids Are Nasty Little Suckers

Aphids are nasty little suckers.  Yep, that's right they can suck the life right out of a plant. Severe infestations of aphids can even lead to a plant's demise by weakening it and making it more susceptible to attack from other insects and more vulnerable to injury from environmental stress. Some types of aphids inject toxins into the plant as they feed, causing distorted and malformed growth. Certain aphids even spread disease as they move from plant to plant.

Appearance

Aphids are soft-bodied insects with a pear-shaped body.  Different aphids come in different colors... green, black, grey, red, purple, and yellow.  Most aphids you'll find on your garden plants don't have wings, but at certain times of the year they do develop wings.  Aphids are fairly slow moving insects so it's not hard to check them out.  Look for their Acornicles@, a pair of tail pipe-like structures projecting out from the rear of their abdomen.

Sucking Sap

While small, aphids are successful at what they do... they suck sap from plants.  They do this by pushing their tiny stylets (located in their proboscis) into stems, leaves, and even roots.  You might think the stylets are tough to be able to pierce plant tissues, but they're aren't. To protect their thin stylets the aphids secrete a fluid that forms a hard protective coating over them as they push into the plant.  Once the stylets tap into the phloem, the source of the plant sap, the aphid secretes saliva into the plant.  It's believed that the saliva is produced to counteract the effects of proteins formed by the plant in response to the wound caused by the piercing stylets.

Once the aphids tap into the phloem they have access to the sugary sap flowing through these plant conducting tissues.  Plant sap contains lots of sugar, but not much of other nutrients needed by the aphids to survive.  To get the nitrogen they require, aphids must imbibe much more sugary plant sap than needed to sustain themselves.  As a result, they excrete volumes of a sugary liquid, called honeydew, from their alimentary canal.  This excreted honeydew is deposited on the leaves and appears as shiny spots.  When aphid populations are large, honeydew can entirely coat lower leaves, making them very sticky and shiny.

Reproduction

Of the over 4000 aphid species in the world, only about 250 species are considered pests.  The presence of moderate amounts of aphids on a plant doesn't mean a plant is doomed, but it should prompt monitoring of the situation.  Not only are aphids successful at sucking, they're also veryadept at reproduction.  Several immature aphids deposited on a plant will mature in about a week.  Each of these young aphids is usually a female and able to produce 40 to 60 baby aphids or nymphs.  These babies quickly mature and then reproduce, setting off a real baby boom with the population having the potential of growing into the hundreds and thousands quite quickly.  If they become too crowded on a branch or the plant becomes weak andAtapped out@, some of the aphids will develop wings and go off to start new colonies.

Life Cycle

The life cycle of many aphids is pretty straightforward.  Aphids go through simple metamorphosis starting out as an egg and hatching into a nymph in the spring.  The nymphs molt and change into successively larger nymphs and then into adults.  During the spring and summer, the females give birth to live babies (all female) who in turn mature and give birth and so forth.  There is usually enough time during the growing season for several or more generations.  When the aphid colony becomes too crowded or the plant starts to die, some of the aphids will develop wings so that they can fly to other feeding locations.  In the fall, some male aphids develop and mate with females.  The females lay eggs for overwintering.

That life cycle may seem simple, but some aphids are Aheteroecious@.  This means they spend the fall, winter and spring on one type of plant species and then spend the summer on an unrelated plant species. That explains the presence of aphid distorted leaves on certain plants but the absence of aphids when the plant is checked for aphids during the summer.  Examples of heteroecious aphids are the rosy apply aphid on apple and plantain and the lettuce root aphid on poplar and lettuce.  Other aphids are Aautoecious@ spending their life on one species of plant or closely related species.

Managing Aphid Infestations

While aphids are nasty little guys dedicated to sucking away at plant sap, light to moderate infestations usually cause no real harm to healthy mature plants.   Control is often desired by gardeners for aesthetic reasons or because the excreted honeydew is creating a problem.  On vegetable crops, gardeners may feel a need to control aphids because their presence diminishes their enjoyment of their produce.  The least toxic way to manage an aphid infestation is the use of a strong force of water from a garden hose to knock the aphids to the ground where most will not be able to crawl back up the plant.   Of course this method is not practical for delicate plants or those without stiff stems.

Summer oils and insecticidal soaps work well against the soft-bodies of aphids. However, be aware that these materials must come in direct contact with aphid bodies because they work by disrupting their membranes.  Soaps and oils don't have any residual effect and must be reapplied when aphid numbers increase again.  If the aphids are protected by distorted and curled leaves, these materials will not work because they don't come in contact with the aphid bodies.  It's also important to note that many aphids feed on the undersides of leaves.  Oils and soaps must be directed to the surfaces where the aphids are feeding to be effective.  Be sure to check for label directions and precautions, such as not using oils in hot weather or using soaps or oils on sensitive plants.

There are also a number of spray insecticides, such as malathion, diazinon, and acephate, that attack the nervous system of the aphids and can provide aphid control.  Adequate coverage is also needed with these materials for them to be fully effective.  However, when you use these materials you will probably also be killing a number of aphid enemies, such as lady beetles, lacewings, syrphid fly larvae, aphis lions and tiny wasp parasites.  These aphid enemies may have been helping you by keeping aphids and other pests in check.  Without their help, pest problems may build to threatening levels.

Systemic Insecticides for Aphid Control

There are also several systemic insecticides that can be used in aphid management.  They're applied to the soil and taken up into the plant sap.  When the aphids feed on the plant sap, they imbibe these and become poisoned.  One advantage to using the root-applied systemics is their ease of application.  They're applied to the soil and taken up by the roots... there's no spraying and very little equipment is needed.

Another advantage to the root-applied systemics is that most of the beneficial insects are not harmed by their use.  Di-syston is one of these materials.  It has been on the home garden market for a number of years and is applied to the root zone of plants as a granular and watered in.  It's a popular material for use in Arose systemics@.  Imidacloprid is another root-applied systemic that just became available to home gardeners a couple of years ago.  It's mixed with water and applied as a drench to the base of a tree or shrub.  It works very well and lasts all season long, but it's quite expensive when compared to oils, soaps, or the spray materials available for aphid control.  Imidacloprid is currently only available to gardeners from the Bayer Advanced Garden products line.  It's in Bayer Advanced Garden Tree & Shrub Insect Control Concentrate@.