Transcript Unit 12: Soybean Insects

Unit 12: Soybean
Insects
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
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Unit 12: Soybean Insects
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Guidelines for insect toleration:
 Up
to 35% defoliation during blooming
 No greater than 20% during pod filling
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Leaf feeding Insects
 Three
pests to worry about:
Two-spotted spider mite
 Bean leaf beetle
 Soybean aphids
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Unit 12: Soybean Insects
 Spider
Mites
Feed on underside of the leaf
 Suck juices from the plant
 Symptoms
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Yellow to whitish spotting on top side of leaf
 Webbing on underside of the leaf
 Severely infested leaves die
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 Bean
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Leaf Beetle
Feeds on leaves causing defoliation
Unit 12: Soybean Insects
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Can also feed on the pod, causing scarring and
seed damage
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Treat when 5-10% of pods are damaged
Larvae
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Can feed on roots and root nodules
Unit 12: Soybean Insects
 Soybean Aphids
Found for the 1st 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
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Unit 12: Soybean Insects
Caused crinkled/cupped leaves
 Have reduced yields by as much as 28% in China
 Very difficult to treat
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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
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Insecticide applied
Not treated
Unit 12: Soybean Insects
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Pod & Flower Feeding Insects
 Cause
direct yield reduction, especially if
infestation occurs late in blooming
 Damaging insects
Bollworms
 Stink bugs
 Mexican bean beetle
 Grasshoppers
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Unit 12: Soybean Insects
Green clover worm
 Velvet bean caterpillars
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 How
do they cause damage?
Unit 12: Soybean Insects
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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
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Unit 12: Soybean Insects
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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
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