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Diseased raspberries are susceptible to numerous virus diseases. Once they are infected, plants can't be cured. Viruses are commonly spread by aphids or infected pollen. To prevent the spread of viruses, destroy all infected plants.
Verticillium wilt is a soil-borne fungus. When a plant is infected, its leaves turn yellow and eventually die. Canes often turn blue as the disease proceeds up the canes, while vascular tissues generally exhibit red discoloration.
The most effective way to control viruses and verticillium wilt is to plant certified virus- and verticillium wilt-free planting stock. You can avoid most of these problems for several years by purchasing only quality, true-to-name, disease-free raspberry varieties.
During hot, dry weather, raspberries often become infested with spider mites. The mites are not obvious, but their presence is indicated by tiny yellow spots on the leaves, which eventually turn brown.
Spray the mites, which feed on the underside of the leaves, with water or an approved miticide according to label directions. Observe the required waiting period between spraying and harvesting, as stated on the label.
Raspberry cane borers symptoms include a sudden wilting and drooping of tops of canes. The white larvae of the borer, if left uncontrolled, burrow down through the cane and kill it.
Remove infected canes at the first sign of an infestation. To control this insect, apply Sevin (carbaryl) or another insecticide before blossoms open. Follow directions on the label when applying any insecticide.
Earwigs are insects with pinchers that hide on the fruit. They will eat the blossoms and hide in the berries. Never spray when plant is in bloom. Find and destroy the hiding places and trap the insects when appropriate.
Grasshoppers eat the foliage and reduce yields. Control grasshoppers in vacant lot or field before they invade your garden. Spray when insects are small before they get wings Use netting if you are plagued with large, flying grasshoppers.
Iron chlorosis is a serious problem when growing raspberries in Utah. Treat plants that show symptoms of iron chlorosis with foliar applications of iron sulfate in the spring. Plants can also be treated with foliar or soil applications of iron chelates. Use only chelated materials for soil applications.
Avoid foliar applications of these materials during flowering because flowers may be burned. Follow label rates for best results. Sequestrene 138 or Miller's Ferriplus iron are the best chelated materials to control iron chlorosis.
Larry A. Sagers
Horticulture Specialist
Utah State University Extension
Thanksgiving Point Office
