Insect Pests of Grain Sorghum, Soybean and Sunflower

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Insect Pestsof Grain Sorghum, Soybean and
Sunflower

• Tom A. Royer
• Oklahoma State University

NCIS MPCI Crop-Hail Sunflower, Soybeans,
Cotton Grain Sorghum School August 23, 2006
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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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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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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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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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Insect Pests of Grain Sorghum, Soybean and
Sunflower

• Seed/seedling feeders
• Stem/stalk feeders
• Foliage feeders
• Seed feeders

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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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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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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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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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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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Seedling feeders in sorghum
Feed in groups at base of plant, may often feed
below soil line, 7-10 bugs can stunt small
seedlings
Migrate from wheat, often see most severe injury
at edge of field
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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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Soybean stem feeders

• Three-cornered alfalfa hopper
• Piercing-sucking mouthparts. It feeds and
  circles around the stem effectively girdling it.

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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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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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Sunflower stem feeders

• Stem weevils
• Sunflower stem weevil (Cylindrocopturus
  adspersus)
• Black stem weevil (Apion occidentale)
• Dectes stem larva

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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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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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Sunflower defoliators
Grasshoppers
Thistle Caterpillar
Sunflower Beetle
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Defoliators In SunflowerNature of Damage

• Pests that feed on foliage. Chewing mouthparts.
  
• Damage leaves, causing indirect damage to
  sunflower yield
• Reduce photosynthesis, slow growth, shift plants
  emphasis to compensating for foliage loss
• Probably information that would help with
  assessing yield loss from hail.

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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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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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Sorghum seed feeders

• Sorghum midge
• Larvae feed for 7 - 9 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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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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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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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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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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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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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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Grasshoppers in Soybeans

• Grasshoppers will feed on pods, causing chewing
  injury. This also allows entry for seed
  disease-causing organisms.

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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 wont 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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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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Insect Pestsof Grain Sorghum, Soybean and
Sunflower

• Tom A. Royer
• Oklahoma State University

NCIS MPCI Crop-Hail Sunflower, Soybeans,
Cotton Grain Sorghum School August 23, 2006