Unit 12: Soybean Insects

Carefully monitor both damaging and beneficial insects through scouting Have knowledge of economic thresholds for insect damage and the cost of control One insecticide application should be enough to control most infestations

Unit 12: Soybean Insects Guidelines for insect toleration:  Up to 35% defoliation during blooming  No greater than 20% during pod filling Leaf feeding Insects  Three pests to worry about: Two-spotted spider mite Bean leaf beetle Soybean aphids

Unit 12: Soybean Insects  Spider Mites Feed on underside of the leaf Suck juices from the plant Symptoms  Yellow to whitish spotting on top side of leaf  Webbing on underside of the leaf  Severely infested leaves die  Bean Leaf Beetle Feeds on leaves causing defoliation

Unit 12: Soybean Insects Can also feed on the pod, causing scarring and seed damage  Treat when 5-10% of pods are damaged Larvae  Can feed on roots and root nodules

Unit 12: Soybean Insects  Soybean Aphids Found for the 1 st time in the U.S. in 2000 Little is known about them Eggs overwinter on buckthorn plants Can have 18 generations/yr As colonies increase, they spread Usually found on leaves and stems Feed by sucking fluid from the soybean leaves

Unit 12: Soybean Insects Caused crinkled/cupped leaves Have reduced yields by as much as 28% in China Very difficult to treat  Weather can cause a population crash quickly  Predatory control  Infestation can increase 10x in a week  Insecticide may only control for small period of time  May take 2 applications for control

Not treated Insecticide applied

Unit 12: Soybean Insects Pod & Flower Feeding Insects  Cause direct yield reduction, especially if infestation occurs late in blooming  Damaging insects Bollworms Stink bugs Mexican bean beetle Grasshoppers

Unit 12: Soybean Insects Green clover worm Velvet bean caterpillars  How do they cause damage?

Unit 12: Soybean Insects Stem Feeding Insects  Rarely cause economic losses  Can puncture stem to suck juices  Control measures usually not needed  Problem pests Three-cornered alfalfa hopper Weed borer

Unit 12: Soybean Insects Seed & Seedling Feeding Insects  Feed on seed, seedling, plant roots, leaves  Usually controlled with soil applied insecticides or seed treatments

Unit 12: Soybean Insects  Damaging pests Seed corn maggot Seed corn beetle Wireworm Grape colaspis White grubs Thrips Southern corn rootworm Bean leaf beetle