Fruit Pest Update

Cherry Fruit Flies Fruit flies will infest virtually 100% of the cherries if they are not controlled. At the present time there are no practical methods that do not use pesticeds. Check with local garden centers and read and follow all label directions. Make certain the pesticide formulation you use in registered for the pest and make certain that you follow all the requirements including the days to harvest. Do not pick the fruit prior to the time this has passed.
Control is much more effective if the entire neighborhood sprays at the same time otherwise the flies move from one tree to another and lay their eggs inside each cherry.
If you decide not to spray, consider removing the trees so they do not infest others in the neighborhood. If no one sprays, you may want to eat the cherries with your eyes closed. Don't ask... Don't tell. The worms will not hurt you.
SPRAYING UPDATE
Western Cherry Fruit Fly: the first cover spray for WCFF is past due for the Kaysville area. A few flies have been caught in Utah County starting on June 1. That would put the cover spray between June 8-11 (7-10 days after the first catch). For Areas without traps, apply the first cover sparay when the fruit starts to change color from a green to a straw (yellow) or salmon blush. Always read and follow instructions on the labels!
Peach Twig Borer: the first cover spray for PTB has moved back a little, due to the cool weather las week. The timing for the cover spray is predicted to be next Tuesday (June 12) for Genola, Spanish Fork and Payson, Thursday for Provo (June 14), Saturday (June 16) for Kaysville, and Sunday (June 17) for Ogden. Other sites will be June 18 or later. Insecticides: Thiodan (endosulfan; 30 day PHI) Imidan (phosmet; 14 day PHI) and Success (spinosad; 14 day PHI) Sevin (carbaryl; 3day PHI) should be used on trees that are near harvest.
Spider mite populations continue to be generally low. Small populations have been found on broadleaf weeds in ground cover and on lower leaves in only a few orchards. As temperatures begin to increase in June, continue to scout regularly for mites. Populations can build very quickly. Sticky trunk bands have been placed in representative orchards in Utah County and Kaysville to determine if this monitoring method can provide some early warning when mites begin to move into trees. Maintain a healthy cover (avoid excess drying) to keep mites on the ground cover. Avoid excessive mowing and herbicide applications during late June through August.
Rosy Apple Aphid: some substantial populations of rosy apple aphids were detected in a few orchards. Rosy apple aphids can cause distortion and reduction of fruit growth on adjacent limbs. If more than 10-15% of shoot terminals are infested with rosy apple aphids, a treatment should be considered. Rosy apple aphids should move to other plants (alternative hosts) by lat June to the first of July, so treatments after the middle of July should not be needed. Insecticides, insecticidal soap and horticultural oil are recommended aphicides.
Very few green apple aphids have been detected.
Update: June 16
Very few Western Cherry Fruit Fly have been reported. That doesn't mean that you don't need to spray. It is time for all areas to put on sprays for WCFF control, if you haven't already.

The Black Cherry Aphid is causing sticky clumps of curled leaves on sweet cherry trees. Check for ladybugs and other predators. If they are present ignore the problem. If you are spraying for cherry fruit fly, the aphids are not usually a problem. If they persist, spray them with insecticidal soap or an approved insecticide.

Leaf Slugs Pear, cherry, rose, cotoneaster and some related plants are often attacked by sawfly larvae. The insects are called leaf slugs because they resemble tiny slugs, but they are not related. They remove the upper leaf surface as they feed and cause extensive browning of the foliage. When damage is severe, it affects the ability of the tree to produce food. This insect is one of the easiest to control. Hot, dry weather will often kills them. Dry soil sprinkled on the leaves will also desiccate and destroy them. Insecticidal soaps or summer weight horticultural oils are also effective.

Greater Peach Tree Borer

Moths have been caught in Utah Co. (Payson, Santaquin and West Mountain (not in Genola, yet) and Kaysville this week. It is time to put on the control treatments (No wait period). In general, peach, nectarine and apricot should be protected. In southern Utah, sweet cherry may also be attacked, and may need to be protect. Female moths mate and begin laying eggs soon after emerging. Eggs are laid on the lower trunk. Eggs hatch within 9 to 10 days. The larvae bore into the trunk, where they feed in the cambial layers, causing the damage. Once the larvae are inside the bark, they are protected from insecticides. Peachtree borer treatments are preventative (not curative).

Apple Scab:

The weather has been too dry infection periods to occur. Summer storms happen quickly and then they are gone. This prevents the leaf wetness time needed for scab infections.

Fire Blight:

Bad shoot blight infections are occurring on Gala apple trees (Northern Utah County) and other locations. Check for new infections, especially after hard rain or hailstorms. Break out new infections about 8 - 12" below the active infection site. Remove infections as soon as possible, but only during dry weather.

Earwigs are a perennial problem although they are not as bad as many gardeners fear. Earwigs can be controlled using baits and/or sprays but an easy and effective alternative is to put out loosely rolled newspapers in the areas where they hide. They generally hide in the moist, cool location around bushes or underneath cover. Every morning, pick up the newspapers and throw them in the trashcan. Consider putting out tuna fish cans with one-fourth inch of bacon grease in the bottom. The earwigs will get in at night and can be discarded the next day.

If they are invading fruit trees, spray Tanglefoot around the trunk or wrap the trunk with corrugated cardboard or moist burlap. The insects will collect there during the day and can be discarded. Earwigs are never eliminated but you can keep population to manageable levels.

Phytophthora Crown and Collar Rot of Fruit Trees

Most fruit and nut species are affected by a disease known as crown rot, collar rot, or Phytophthora collar rot. It is a serious disease; frequently killing trees 5-7 years old, just as they begin to bear fruit.

Collar rot shows as dead areas on the trunk called cankers between the soil line and crown roots. Cankers are difficult to detect when young, but as they enlarge, they turn dark and sink and girdle the tree.

This disease is not easily diagnosed from symptoms in the top of the tree. Scattered yellow leaves occur on trees in mid-season. Infected trees usually have sparse foliage and low vigor. Foliar symptoms may appear only on branches directly above the canker, while the remainder of the tree appears normal and continues to bear fruit. Some trees remain alive for 2 to 3 years, while others die very quickly.

Ovwerwatering encourages the disease since the fungus is a water mold. It is more serious in heavy, poorly drained soils than in light, well-drained soils, although it can occur in almost any improperly irrigated soil.

Collar rot is difficult to control because it is an erratic disease. When infections are discovered, it is usually too late to eradicate the disease and save the tree.

The following control practices should be used to prevent or decrease collar rot:

Choose resistant varieties and rootstocks. The most susceptible apple rootstocks are Lodi, Grimes Golden and Duchess. Golden Delicious, Jonathan, McIntosh and Rome Beauty are moderately resistant. Red Delicious, Wealthy and Winesap are considered to have good resistance. Seedling Rootstocks appear somewhat tolerant of collar rot.

Do not form a basin around the trunk or place trickle irrigation outlets so that the tree base is continually wet. Always channel water away from the trunk. Keep irrigation periods to less than 8-hour runs. Plant trees on raised beds.

Do not plant trees so that the graft union is below the soil line. This results in increased collar rot and may allow the scion to root thus resulting in loss of dwarfing. Reduce frequency or length of irrigation if used in excess. Soil saturated for more than 36 hours is conducive to disease.

Spider Mites:

Spider mites are common pests in the orchard and urban landscape and can inflict serious damage to trees, shrubs and flowers. Both evergreen and deciduous plants are attacked. Spider mites are not insects but are closely related to ticks and spiders. Their common name is derived from their ability to produce silk or webs, which most species spin on host plants.

Mites are tiny, about the size of the period at the end of this sentence. They can also be very prolific, which is why infestations often go unnoticed until plants show significant damage. Mites may live for several weeks. Under optimum conditions, spider mites can complete their development from egg to adult in less than one week, so there are many overlapping generations in a single season. Populations increase rapidly and cause extensive plant damage in a very short time.

Spider mites have needle-like mouthparts and feed by piercing the leaves of host plants and sucking out the fluids from individual plant cells. This causes the leaves to have a stippled or flecked appearance, with pale dots where the plant juices are removed. Prolonged, heavy infestations cause yellowing or bronzing of the foliage and premature leaf drop similar to drought stress. Severely infested plants are be stunted or killed. Most of the mites feed from the undersides of leaves, although the damage is most evident from the upper surface.

Timely inspection of susceptible plants during hot dry weather helps prevent serious damage. Spider mites often re-infest the same plants year after year. Hold a sheet of white paper or foam board under a branch and tap the foliage sharply. If mites are present, they will be dislodged and appear as slow- moving, dust specks on the paper.

Spider mites are difficult to control. Spraying plants with a strong stream of water from a hose dislodges many mites from leaf surfaces. Direct water sprays upward against the lower leaf surfaces, and repeat this technique at regular intervals. Low populations of spider mites can be held in check by naturally occurring predatory mites that feed on both eggs and active stages.

Elimination of moderate to heavy infestations of spider mites usually requires the use of specific pesticides known as miticides. Always read and follow the directions accompanying the product you are using. Some miticides may harm or discolor certain types of landscape plants. Thoroughly wet the foliage and try to contact as many pests as possible.

Mite populations should decline with shorter day lengths. Mite control sprays are not recommended after mid August. Two-spotted and McDaniels Spider mites overwinter as diapausing (resting) females. These diapausing females do not reproduce (make new eggs) until next spring. Diapausing females are orange in color. When orange colored web spinning mites are observed, egg production is slowing. Control of diapausing females with pesticides isrecommended.

Peach Tree Borer

Remember to apply the second protective spray for peach tree borer the first part of August. This second spray is needed because the pests remain active until about the first part of September.

Peach tree borer is the most destructive insect pest of peach, cherry, plum, nectarine, apricot, almond and other stone fruits. This pest also attacks the flowering forms of these trees. It feeds under the bark and eventually kills the tree.

Symptoms of borer damage are wet spots or oozing, gummy, sap. Sawdust-like excrement often mixes with the sap giving it a dark color. Damage occurs at the base of the tree beneath the soil line. Oozing wounds higher in the tree are caused by other problems. The most common of these is cytospora, a fungal disease with symptoms that resemble borer damage.

Adult borers are clear-winged moths that resemble a wasp. They are active now and fly during the day. They begin laying their eggs about July 1 and continue for about two months. Each female lays up to 400 eggs at the base of the trunk. The eggs hatch in about ten days and larvae burrow into the trunk through cracks in the bark and start to feed.

The insects feed under the bark through the fall and spend the winter, as partially grown larvae, a few inches below the ground under the bark. In the spring they resume feeding and then pupate in late spring. Adult moths emerge from the pupae and start the life cycle again.

Once inside the tree they are protected from most treatments. The time they are vulnerable is before they tunnel under the bark. Preventive sprays must be applied the first week in July and again the first week in August.

The most effective product is Dursban7 if it is still available. Otherwise use registered formulations of Thiodan. Use the amount of spray recommended on the label. Keep the spray off the fruit and leaves.

Apply the second spray about August 1. More frequent sprays are needed if sprinklers hit the trunks regularly.

Organic controls include parasitic nematodes. They are released at the base of the tree after the larvae become active. Other types of controls including companion planting are not effective and cannot be relied on to successfully control this pest.

There is strong evidence that trees showing signs of stress or other damage are more susceptible to borer attack. Keep trees healthy by avoiding over watering and damage to the trunk by string trimmers and lawn mowers. Inspect trees carefully and apply the preventive controls as needed.

Codling Moths:

Since this has been a warm summer, we are going to have at least a partial third generation of codling moths in Northern Utah. Generally we need to protect the fruit through the first or second week of Sept. After the second week of Sept., the photoperiod (day length) becomes too short for eggs to hatch. If the beginning of a third generation occurs before this time then an additional cover spray is recommended.

Timing of fruit maturity and harvest needs to be considered along with the pre-harvest interval (PHI) of the product used. Select a product with a PHI that will elapse before the planned harvest date. Cultivars that are harvested before Sept. 7 will not need an additional cover spray. For information on what to use see previous advisories.

Black Locust Borer:

The Black locust borer is one of the few borers that attack the trees in late summer or early fall.

Host: Black locust, Robina pseudoacacia, may also attack honeylocust, Gleditsia and willow, Salix.
Life Cycle: One generation per year.

After overwintering as an immature larvae under the bark, it resumes feeding about the time buds begin to swell. Sap oozing from the bark surface in the spring indicates the resumption of feeding, which continues until late July. After pupating in the tunnels, adults emerge late July to the end of August. The adult is about 18 mm in length and a jet-black, long horned beetle with bright yellow bands. Eggs are laid near wounded bark. Mature larvae are round headed borers, white, about 25 mm long and cylindrical. The adult borer seems to prefer trees that are at least four years old. Once trunk diameter has exceeded 15 cm, it becomes less susceptible.
Damage: The feeding tunnels of the grubs weakens wood and trunks become swollen in areas where feeding occurs.
Control: Destroying infested trees and branches during winter and spring will control overwintering larvae. Probing holes with a sharp wire may destroy larvae. The adults are active now and are visible crawling on the branches of the trees. Apply chemical controls to the bark to control hatching larvae before they bore into the trunk. Use an registered chemical to control the pest.

Sap Beetles:

The most common question from calls and email that listeners had about fruit last week was, “ What are the little black bugs on my peaches.”

The tiny black beetles are Nitidulids or sap beetles. They are not specific to peaches or any other crop but are only after anything sweet. We get numerous questions about this same pest on sweet corn when it is in season. They commonly infest corn, tomatoes, peaches, raspberries, strawberries, and muskmelons that are wounded or overripe.

Most sap beetles are small, between 1/8 and 1/4 inch long, and oval in shape. They are black or brownish, sometimes colored with orange or yellow spots.

Sap beetles often become a nuisance in gardens during late summer. They feed on very sweet, damaged, overripe, or decomposing fruits and vegetables. The adults are attracted to any fermenting smell and are commonly found around garbage containers, foods and gardens where fruits and vegetables are being grown. When they attack your outdoor meal they are called picnic beetles.

Sap beetles do not normally attack healthy, intact fruits and vegetables. However, if they are attracted to a garden by fermenting, overripe produce, they may also attack undamaged, developing fruits and vegetables, particularly berries or corn.

Sap beetles are difficult to manage. Sanitation is the most effective means of reducing beetle numbers. Remove and destroy damaged or overripe produce. Harvest produce as it ripens. This helps eliminate the odor and availability of susceptible fruits and vegetables.

Insecticides are not very effective in managing sap beetles. These insecticides may kill existing beetles, but as long as food odors are present, they can not prevent additional sap beetles from moving into gardens.

Most of the problem in the peaches can be traced to damaged peaches. They peaches often have split pits that allow the beetles to invade or they have twig borers that have damaged the fruit near the stem end. Pick up and discard fallen fruits. Damaged fruit should also be removed from the tree before it attracts the borers.

Russeting:

Russeting is a brown, corky netlike condition on the skin or brown skin on pears. It may appear on only a small part of the skin or it may cover the entire surface. Severe russeting may be accompanied by fruit cracking that usually renders the fruit useless.

Russeting is associated with specific environmental conditions, damage from harsh chemicals, excess nitrogen, or infection by certain fungi, bacteria and viral organisms. The fruit on younger or vigorously growing trees seems more prone to russeting than fruit on older, slower-growing trees. Some russeting is normal on certain varieties of apples, crabapples, and pears, and is not a defect in these varieties.

When russeting occurs early in the season, the skin becomes thin and tight. It does not with the developing, enlarging fruit, so it cracks. The cracks in the flesh allow fungi and bacteria to enter and rot the fruit. When russeting occurslater in the fruit development, the skin becomes brown, dull, and rough but does not crack.

Weather-induced or physiological russeting, usually occurs within 30 or 40 days of bloom. It is thought to be caused by late frosts or rainy springs. High temperatures and excess nitrogen may also be involved. This russeting may occur uniformly over the entire surface of each fruit, but it might be worse on some fruits than others.

Russeting may also be caused by caustic sprays. Spray-induced russeting often occurs only on the exposed side of apples. The use of emulsifiable concentrate pesticide formulations are more likely to cause russeting than wettable powders (WPs).

Some suggestions for reducing russeting include the following.

Powdery mildew sometimes causes russeting on apples. Control the mildew to prevent the damge.

Russet mites are likely cause brown skin on pears. They cannot be controlled now but must be controlled with a dormant oil spray in the spring.

Avoid spraying emulsifiable concentrates (ECs).

Do not apply chemicals during slow drying conditions, high humidity, or temperatures above 90°F.

Prune properly to encourage good air circulation and speed fast drying after rains. Thin fruits to only 1 or 2 per cluster within 3-4 weeks of peak bloom.

Surface russeting damages the appearance and skin of the fruit but not the flavor or nutritive value of their flesh. As long as they are not cracked, russeted fruits will store in the refrigerator.

Because fruit russet one season, it doesn't mean it will cause problems every season. Sometimes even susceptible trees can go for years without much difficulty. If a tree has problems every year, consider replacing the tree with a different variety. KSL Greenhouse Tip Larry A. Sagers Regional Horticulturist Utah State University Thanksgiving Point Office

Moths & Mites

Because the days are shorter and cooler, codling moths are no longer laying their eggs. That is good news for fruit growers and means the pest control season is over for apples and pears.

Many people are concerned about the brown spots on the leaves of their apples and pears. These slightly raised velvety spots are caused by a tiny eriophyd mite called a blister mite.

Eriophyd mites are different than spider mites. They are much smaller and have a cylindrical shape. Because they are so small it is impossible to see them without the aid of a microscope.

Although the leaf spotting looks bad and visually causes a great deal of concern, the actual damage is minimal. Thee mite do not respond to insecticidal treatments nor do they respond to most miticides. The best control is to use a dormant oil spray in the early spring. This oil spray smothers the creatures by plugging up their breathing holes. There is nothing that can or should be done now.

Russet mites also cause the skin of pears and some apple varieties to turn brown and woody. Once this happens, it is to late for effective controls. Once again use the dormant spray in the early spring.