Transcript Turf Insect Management

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
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: reddishbrown 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 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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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 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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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.
Oklahoma State University
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