Fruit Pest Update

Fruit Pest Update 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. Peach Twig Borers: The first cover spray date for Peach Twig Borers is due by June 12 for Genola, June14 or 15 for Salt Lake and Ogden, June 16 for Bountiful, Payson, Perry and Spanish Fork. Other areas are projected to be due next week or later. Check the spray date table found on the web at http://extension.usu.edu/ipm/spraydd.htm for additional information. Do not treat peach trees without fruit for Peach Twig Borers. This cover spray is for protecting against wormy fruit. Check labels for registered pesticides. Western Cherry Fruit Flies: Apply the first cover spray can be applied when the fruit starts to change color; from a green to straw (yellow) or salmon blush. The color change has occurred on Sweet Cherries in most areas. Apply malathion or pyrethrum/rotenone mixture to control the worms. Mites are still present in the lower crown area of the trees. Both McDaniels and Two Spotted mites on tart cherry leaves. Two spotted mites and a few European Red Mites were found on apple trees. So far populations have remained low, but they can increase rapidly. Check for predators if mite populations are high. Predators can give excellent mite control, but are killed by mite sprays. Black Cherry Aphids: The most notable pest on my trees right now is the black cherry aphid. The terminal ends of many branches are covered with twisted, sticky leaves. Unfolding these leaves reveals hundreds of shiny black aphids. I usually depend on ladybugs to control these aphids, but the cold weather has made them relatively ineffective. If they don’t solve the problem wash the undersides of the leaves with a strong stream of water. If that doesn’t help use some insecticidal soap Trees sprayed for cherry fruit fly are not usually bothered. When only a few branches are affected, prune them off and destroy them. Larry A. Sagers Regional Horticulturist Utah State University Extension Thanksgiving Point Office