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.

Large Trees and Surface Roots

Large Trees and Surface Roots

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist  

Have you ever noticed those big, gnarly roots of trees that come to the surface and create all sorts of problems with sidewalks, driveways, and lawns?  They can make mowing almost impossible.  What can you do to solve the problem... short of cutting down the trees?

How do those roots get there? The woody roots of most trees and shrubs are only about 12 to 18 inches deep in the soil.  These roots grow and radiate out from the tree trunk in a horizontal network. 

As a tree grows older and larger, their branches and trunks grow in girth or diameter and so do their roots.  As they grow in diameter, the roots “come to the surface,” but actually they’ve always been there, they’ve just gotten bigger.  Surface roots become a problem sooner or later on most large trees.  However, they become a problem more quickly with fast growing tree species, such as silver maple, Norway maple, cottonwood, sycamore, elm, and willow.

So what can be done about these roots?  Cutting them all off right at the trunk isn’t a good solution, if you want to keep the tree.  These larger roots are the major “pipelines” for the transport of water and nutrients to the tree.  When you sever the roots, you are preventing the uptake of water and nutrients.  We should also keep in mind that the roots help to anchor the tree.

How about covering the roots with soil?  Most tree species will not tolerated a significant change of grade.  Extra soil placed on top of the roots leads to the suffocation of roots and the eventual death of the tree.  The least drastic approach to take with “surface roots” is to mulch the problem area with a three to four inch layer of mulch.  A coarse mulch that allows for the free flow of air and water into the soil is best.  Some good choices include coarse bark mulch, wood chips, coarse compost, or pine needles.  Keep the materials six inches or more away from the trunk to deter rodents and to prevent damage from freezing and thawing.

Another option would be to cover the area with a shade tolerant groundcover.  Many times the root area directly beneath a tree is bare because the dense shade is not conducive to grass growth.  Soil erosion from wind and water often follows, making the area increasingly difficult to mow and quite unattractive.  Groundcovers adapted to shady conditions can be used to hide the roots and to avoid the need for mowing.  Consider the use of ajuga, vinca, pachysandra, or other shade tolerant groundcovers. 

It’s okay to plant a groundcover, but don’t come in and mound soil around the base of the tree so you can plant flowers or shrubs.  This soil around the base of the tree can lead to rot in that area and cause the gradual death of the tree.

Mulch or groundcovers aren’t going to solve the problem of roots that are damaging your foundation, driveway, or sidewalk.  Something has to be done! If the tree is already large you may want to consider the use of root pruning.  Root pruning will hurt the tree, but if done properly you can attempt to keep the damage to tolerable levels. 

WSU Cooperative Extension of Spokane County recommends pruning the roots over a period of at least three years.  They suggest in their bulletin “Surface Roots” to slice straight down into the soil at regular intervals along part of the length of the encroached structure or feature, marking where the cuts were made.  The following year make more cuts and continue yearly until the entire length has been pruned.  “If more than 1/3 of the tree’s roots are severed at any one time, there will likely be noticeable damage to the tree, such as dieback of limbs and branches, stunting of growth, and leaf drop.  Every year, you should also re-cut the previous years’ cuts to keep the roots from reentering the area.”

Keep in mind that you are compromising the structural integrity of the tree when you cut any of it’s major roots off, especially when they’re close to the trunk.  The more roots you cut, the bigger the compromise.  If a major portion of a root system must be pruned to save a structure or feature, it may be better to simply remove the tree. If you don’t remove the tree, it may come down in a windstorm.

If you have a younger tree that you realize was planted in the wrong place and will eventually be the cause of a root and structure clash in the future, you can perform root pruning earlier to prevent damage from occurring and to avoid significant damage to the tree later in life.  This type of root pruning is done by slicing straight down into the soil about 12 inches away from the structure or feature.  You are slicing through small roots instead of large major roots of mature trees.  To prevent encroachment in the future, the roots must be cut along the same line every year.  This same procedure can be used if tree roots are encroaching on garden areas.  The earlier you start and the smaller the roots cut, the less damage that will occur to the tree.

The real cause of troublesome surface roots is planting a large tree species that is very fast growing and placing it where it will become a problem.  Select the right size tree and situate it where it won’t be a problem as it grows larger.

Why Leaves Turn Color in the Fall

Why Leaves Turn Color in the Fall

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

Tree leaves contain different types of pigments.  The predominant one is usually green and it comes from the chlorophyll needed for photosynthesis... the process by which the leaf captures sunlight and uses that energy to make sugars out of water and carbon dioxide.  In the fall as the leaf begins the process of senescence or dying and falling off the tree, photosynthesis stops and chlorophyll breaks down, revealing the underlying yellow and orange pigments in the leaf...these are carotene (orange-yellow pigment), and xanthophyll (yellow). Red and purple colors come from anthocyanin pigments. Anthocyanins are not masked but actually start to build up in the leaves of certain trees as the chlorophyll breaks down.

The weather that leads to the best fall colors are those which promote the highest levels of sugars in the leaves.  Bright, sunny warm days and cool nights will lead to the most brilliant hues of oranges through reds and purples. Heavy frosts and overcast days can diminish fall color, while a mild drought can favor anthocyanin production and fall red color.&

Its important to point out that some trees such as red maple, dogwood, sweetgum, and dogwood are capable of exhibiting fall color under the right conditions and other plants, such as sycamore, black locust, black walnut, linden, catalpa, and elm will never provide an attractive autumnal display.

Conifers are cone bearing trees. Most conifers are needled evergreens. While most conifers don’t lose their leaves in the fall, they do lose some of their oldest needles each year. This is usually a gradual, unnoticed process, but in some years needles may turn bright yellow in the fall and drop over a short period of time. There are a few deciduous conifers, such as larch and dawn redwood, which lose all their needles each fall.

Why Prune Our Trees?

Why Prune Our Trees?

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

If someone knocks on your door and tells you you're trees needs pruning, beware!  This person may be a qualified arborist looking for work or they simply may be a chainsaw owner looking for some good firewood.  First let's examine the reasons why a tree might need pruning.

Dead limbs or branches with a core of decayed wood are hazardous. They should be removed whenever they become evident.  Also, broken limbs and branches should be properly pruned as soon as possible after the damage has occurred.

Limbs and branches that interfere with utility wires, gutters, roofs, and chimneys should be removed.  Branches that create a safety hazard by obstructing a view of the street or sidewalk should be removed using proper pruning techniques.  Branches that intersect and rub should be pruned to eliminate the problem.

Tree pruning is sometimes employed to lessen crown density in order to reduce wind resistance, to shape the tree, or to allow for greater light penetration. Beware if someone says your tree needs pruning because it's "too big."  Keep in mind that healthy trees with adequate root systems seldom "NEED" pruning just because they are big.  That just isn't true. 

In some cases, tree removal may be a better option than pruning.  Trees warrant removal if they are obviously dead or dying.  Trees definitely should be removed if they pose a serious hazard because of internal decay or the destruction of a large portion of their anchoring roots.  If pruning can't remedy the situation, trees growing too close to a building or crowding other trees should be removed.

Good landscaping can add 15 to 20 per cent to the value of your home.  Healthy, attractive trees are an asset to your landscape's design.  Unhealthy, poorly pruned trees are a liability.  When you hire someone to prune your tree or to help you decide on removal, you should look for a qualified, trained certified arborist, not just anyone who knocks on your door.

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.

Austrees and Hybrid Poplars

Marianne C. Ophardt
Washington State University Extension
Area Horticulture Specialist  

They often sound too good to be true... advertisements for fantastic plants and super trees.

The Austree is actually a hybrid willow tree.  It's a cross between the Hankow willow (Salix matsudana) and white willow (Salix alba). Willow trees are fast growing trees and the Austree is no exception.  The advertisement indicates that they're "very fast growing" and can grow as much as fifteen feet a year.  I don't doubt this one bit, especially with our local summer sunshine and heat. The advantages to a fast growing tree are obvious, but fast growing trees tend to have soft wood that breaks easily and is prone to wood rot. 

Fast growing trees also tend to have large, invasive roots systems, and the Austree is again no exception.  The ultimate mature height of the tree is 50 to 70 feet and the literature suggests that the roots can extend into the soil two to three items the height of the tree.  Austrees are used to stabilize slopes and minimize soil erosion in gullies.  This implies a very invasive root system... it has to be to help hold onto the soil.

The literature also indicates that the Austree has problems with alkaline soils where the pH is above 6.5.  Most of our local landscape and garden soils are above 8.0 which means that the Austree may have problems here.  This can be ameliorated by fertilizing with an acidifying fertilizer, such as ammonium sulfate or sulfur coated urea, on a regular basis.  Failure to amend the soil could lead to poor growth and performance.

The Austree is also susceptible to the same pests and diseases as other willows growing in our area.  The two most common pests that I've seen on willow leaves are aphids and mites. These can be controlled with applications of pesticides, but it may be difficult spraying large trees.  

What it all comes down to is that Austree should not be considered as a shade tree for a regular- sized or small home lot.  They should work well here for stabilizing slopes, creating a dust and noise barrier, acting as a windbreak, acting as a wildfire break, or providing a privacy screen.  They should also be useful in creating shelterbelts and wildlife habitat. 

The important thing to remember is that they do have an extensive and invasive root system.  They should be located where this will not create a problem with driveways, sidewalks, septic systems, buildings or other structures. Another thing to know about making the Austree into a hedge or windbreak is that they should be planted about three feet apart in a single row planting and five feet apart in a double row planting.

The fact that these trees have lots of roots also implies that these trees like lots of water...  and that's true.  The Austree people recommend that after the seedlings are established they should have a good soaking every three days.  In fact, they recommend irrigating with drip irrigation to make this easier.

Planted in the right place for the right purpose, the Austree might have a place in our local landscape.  However, I'd recommend staying away from it as a shade tree for the home landscape.

Hybrid poplars are another tree being touted by many because they grow so fast.  Just look at the hybrid poplar plantations that are grown for pulp, fuel, lumber, and plywood.  It's truly amazing just how fast some of these hybrids grow!  Unfortunately, the hybrid poplars are not well suited as a shade tree for the home landscape.  The same reasons that make the Austree willow unacceptable also apply to the hybrid poplar... they have invasive roots and brittle wood.  Large limbs of brittle wood and potential wood rot lead to limb breakage and potentially hazardous situations.

However, the hybrid poplars do grow fast and are less susceptible to some diseases than Lombardy poplar, the variety traditionally used for windbreaks.  These new poplars are preferable over the Lombardy for windbreaks because of their rapid growth, their dense green foliage, and the absence of root sprouting.  The use of male clones can also avoid that nasty problem of blowing cotton.

The Rocky Mountain Austree Company offers two interesting hybrid poplars. One is called 'Rapid Merlot'  which leafs out in the spring with deep green and maroon leaves.  The leaves turn darker green during the summer and change to maroon again in the fall.  The Austree company notes that this is a good tree for windbreaks and can grow from 10 to 15 feet in one year.

`Gold Panner' is also a hybrid poplar offered by Austree Co.  This one only grows five to eight feet a year and is recommended for shade tree use instead of windbreaks.  Keep in mind that this is still a poplar tree and with typical poplar problems. Spring leaves are large and golden-yellow in color with purple stems and veins.  They tend to change to a lime green in mid-summer and then back to a brilliant gold in the fall.  I like my trees a dark green so I'd personally stay away from this tree, but the coloring does sound distinctively different. 

Until recent years local poplars and willows weren't bothered with many serious pests.  However, there is an increasing problem with borers on both poplars and willows in this area.  One borer is the "poplar and willow borer."  There is also the carpenter worm, which attacks both trees too.  These can structurally weaken limbs and can lead to the death of the trees.  Control involves keeping the trees in good health and applying a pesticide spray at the recommended times.

Another insect problem that's becoming widespread on poplars is the lettuce root aphid.  This aphid causes a reddish, flask shaped gall on the leaf stems.  It was first thought to be harmless, but apparently high populations of the pest are capable of causing damage and tree decline.  This insect can also be controlled with sprays... if one has the equipment to spray tall windbreak poplars.

In conclusion, Austree willows and hybrid poplars could have a place in the landscape, but we should realize that they're not problem-free and should be used where you can take advantage of their best characteristics and avoid problems from their poor traits.

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@.