1. Insect Pests of Grain Sorghum, Soybean and Sunflower
Tom A. Royer
Oklahoma State University
NCIS MPCI & Crop-Hail
Sunflower, Soybeans, Cotton & Grain Sorghum School
August 23, 2006

2. Insect Pests of Grain Sorghum
There are many potential pests that feed on the foliage and panicle. The results of their activities can cause seedling death, lodging and unfilled seed
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3. Insect Pests of Soybean
In the past, there were few pests that caused significant damage to soybean. In resent years, several pests have mad their presence felt throughout the soybean growing region.
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4. Insect Pests of Sunflower
Sunflowers are native to North America, therefore we have a wide variety of insect pests and their associated natural enemies.
Damage occurs to the seedling, foliage, stalk, developing head,and seed.
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5. Insect Pests of Grain Sorghum, Soybean and Sunflower
There are numerous pests of these crops, but I will focus on the pests that can cause damage symptoms that resemble hail damage
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6. Insect Pests of Grain Sorghum, Soybean and Sunflower
Seed/seedling feeders
Stem/stalk feeders
Foliage feeders
Seed feeders
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7. Seed/seedling Feeders in Sorghum, Soybean and Sunflower
Wireworms would be a problem for stand establishment in cool soils that delay rapid early growth (early-planted crop). Feed on germinating seed and newly emerged seedlings.
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8. Seed/seedling Feeders in Sorghum, Soybean and Sunflower
Seed corn maggots are a problem in cool soils with higher organic matter. (early-planted crop). Feed on germinating seed.
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9. Seedling feeders in Sorghum, Soybean and Sunflower
Cutworms: several species attack these crops
Black cutworm
Dingy cutworm
Darksided cutworm
Sandhill cutworm
Many others
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10. Seedling feeders in Sorghum, Soybean and Sunflower
Look for stand loss
Look for weak, slow
growing plants
Slow growing conditions (cool weather) favors cutworm damage
Follow-up with presence of insect
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11. Seedling feeders in sorghum
Chinch bugs:
Adults: 1/6 inches, black body and white wing covers
Nymphs: reddish-brown with band of white across back
40-day lifecycle
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12. Seedling feeders in sorghum
Feed in groups at base of plant, may often feed below soil line, bugs can stunt small seedlings
Migrate from wheat, often see most severe injury at edge of field
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13. Oklahoma State University
Sorghum stalk feeders
Southwestern Corn Borer:
More of a pest of corn, it occasionally attacks sorghum
Hollows out stem, causing lodging. Not a major pest of sorghum
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14. Oklahoma State University
Soybean stem feeders
Three-cornered alfalfa hopper
Piercing-sucking mouthparts. It feeds and circles around the stem effectively girdling it.
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15. Oklahoma State University
Soybean stem feeders
Soybean Stem Borer
Longhorned beetle.
Larva is damaging stage, tunneling in stem. They overwinter below girdle, in stem.
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16. Oklahoma State University
Soybean stem feeders
Soybean Stem Borer
Longhorned beetle.
Larva is damaging stage, tunneling in petioles and stems. They overwinter below girdle, in stem.
They also feed on giant ragweed, cocklebur
Larvae tunnel downward, causes lodging on mature plants
Damage often remains unnoticed because it occurs so late.
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17. Sunflower stem feeders
Stem weevils:
Sunflower stem weevil (Cylindrocopturus adspersus)
Black stem weevil (Apion occidentale)
Dectes stem larva
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18. Sunflower stem feeders
Larvae feed on stem cortex, moving down stem as they mature
Cause weakened stalks, particularly a problem when harvest is delayed.
Can help transmit Phoma stem rot
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Soybean defoliators
Fall Armyworm
Corn earworm
Grasshopper
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20. Oklahoma State University
Sorghum defoliators
Fall armyworm/corn earworm:
Damages both whorl and panicle, but most often seen in whorl
Control in whorl is generally not profitable
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21. Sunflower defoliators
Grasshoppers
Thistle Caterpillar
Sunflower Beetle
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22. Defoliators In Sunflower Nature of Damage
Pests that feed on foliage. Chewing mouthparts.
Damage leaves, causing indirect damage to sunflower yield
Reduce photosynthesis, slow growth, shift plant’s emphasis to compensating for foliage loss
Probably information that would help with assessing yield loss from hail.
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23. Oklahoma State University
Sorghum seed feeders
Corn earworm/Fall armyworm:
Damages both whorl and panicle
When feeding on head, they will eat seed until it passes “soft dough”.
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24. Oklahoma State University
Sorghum seed feeders
Corn earworm/Fall armyworm:
Damages both whorl and panicle
When feeding on head, they will eat seed until it passes “soft dough”.
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25. Oklahoma State University
Sorghum seed feeders
Sorghum midge:
Larvae feed for days, total lifecycle is about 2 weeks
Larvae completely destroy the seed
Adults emerge, leaving white pupal case dangling from floret and can re-infest late blooming suckers or fields. Heads are “blasted”.
Johnson grass is alternate host: do not overwinter well in Oklahoma
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26. Oklahoma State University
Soybean seed feeders
Corn earworm
Also known as podworm, feeds on foliage and maturing pods
Occurs in mid to late season
Can severely injure pods
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27. Oklahoma State University
Soybean seed feeders
Bean leaf beetle
Overwinters as adult: 1-3 generations
Feeds on foliage and been pods.
Most damaging to pods.
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28. Oklahoma State University
Soybean seed feeders
Stinkbugs
Typical “stinkbug” shape, green about 7/8 to 1 inch long
Piercing-sucking mouthparts
Lay barrel-shaped eggs, often coppery colored
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29. Oklahoma State University
Soybean seed feeders
Piercing-sucking mouthparts inserted into developing pods
Cause shriveled, misshapen, and discolored seeds that are lower in weight
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30. Sunflower seed feeders
Head clipper weevils chew holes around the stem, effectively girdling it. It breaks over, and could be mistaken for hail injury.
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31. Sunflower seed feeders
Sunflower midge is a pest, usually in the northern plains, that causes the head grow in a distorted way (folding, convoluted). It could mimic hail damage under the right circumstances.
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32. Grasshoppers in Soybeans
Grasshoppers will feed on pods, causing chewing injury. This also allows entry for seed disease-causing organisms.
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33. Grasshoppers in Sorghum
Grasshoppers will feed on developing seed.
Grasshoppers may be more of a problem in conservation tillage because they may be laying eggs in fields which won’t be disturbed by tillage. Eggs may survive better, hatch slightly later, and grasshoppers may be more uniformly distributed in the field.
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34. Grasshoppers in Sunflowers
Grasshoppers are a sporadic problem in Oklahoma, because they can build up in large numbers and caused physical damage to the leaves and seed.
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35. Insect Pests of Grain Sorghum, Soybean and Sunflower
Tom A. Royer
Oklahoma State University
NCIS MPCI & Crop-Hail
Sunflower, Soybeans, Cotton & Grain Sorghum School
August 23, 2006