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| Insecticide
ID Guide |
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LESSER CORNSTALK BORER
Lesser cornstalk borer is an important pest in the southeastern and
southwestern growing areas. It is usually a problem during hot, dry
weather, and is more often a problem on coarse, sandy soils than on
heavier soils. Lesser cornstalk borer larvae will feed on underground
pegs and pods in addition to any part of the plant above ground that
contacts the soil surface.
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FALL ARMYWORM
Fall armyworms are one of several foliage feeders that may attack
peanuts. In some years, they can be the predominant foliage feeder.
Caterpillars, gray, light brown or mottled green in color, reach approximately
1 1/2 inches in length when fully grown and have a prominant inverted
“Y” on their head. When abundant, fall armyworms can strip
plants of foliage and “march” to other host plants. Female
moths lay egg masses of about 150 each and cover them with scales
from their body.
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SOUTHERN CORN ROOTWORM
DAMAGE
Southern corn rootworms are most often found on heavy soils that are
poorly drained. During extremely wet weather, they may become a problem
even on sandy soils. This pest is a subterranean feeder. It may feed
on the roots of peanut plants to some extent, but its most important
damage is due to peg and pod feeding. Usually the holes cut into pegs
and pods will be almost a tiny drill bit. In contrast to lesser cornstalk
borer feeding, there is no webbing associated with this pest.
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CORN EARWORM/TOBACCO
BUDWORM
In peanuts, these two closely related insects are usually referred
to as corn earworms, but tobacco budworms are often a significant
percentage of the total population. Larvae of both species feed
on peanut foliage and are very similar in appearance. The corn earworm
moth (above) and the tobacco budworm moth are often seen in peanut
fields and may indicate that larvae will soon follow.
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LEAFHOPPERS
Leafhoppers are small wedge-shaped, green, brown or black insects
about 1/8 to 1/4 inch in length. Leafhoppers insert their beak into
the midrib on the lower side of peanut leaves and suck plant juices.
Leaves turn yellow from the point where the feeding has occured to
the tip of the leaf and may die in severe cases. This damage is often
referred to as “hopper burn.”
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THRIPS
Thrips are tiny, slender insects about 1/32 inch in length. They
vary in color from yellow to black. Adults will have wings and may
fly when disturbed. Thrips feeding often results in stunted peanut
plants with leaves that are scarred and “possum-eared”
(leaf edges are turned down). Thrips also transmit the virus that
causes tomato spotted wilt in peanuts.
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THREECORNERED ALFALFA HOPPERS
Three-cornered alfalfa hoppers are light green and wedge-shaped. They
stand about 1/4 inch high and are about 1/4 inch long. Both adults
and nymphs have piercing mouthparts and feed by penetrating the stem
and sucking plant juices. They tend to feed in a circular fashion
around a stem, making feeding punctures as they go (see photo). The
damaged area typically swells and above ground root growth may occur.
On peanuts, feeding may occur on limbs, leaf petioles or pegs.
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SPIDER MITES
Spider mites are not really insects, but are closely related to insects.
Although spider mites are small, they can be seen with the naked eye,
especially if they are moving. Spider mites feed on peanuts by sucking
plant juices from the undersides of the leaves. This feeding, which
usually begins near the midribs of the leaves, results in a speckling
of the upper surfaces of the leaves. As infestations become more severe,
leaves turn yellow and die. Heavy infestations are characterized by
visible webbing.
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WIREWORMS
Wireworms are the immature stages of “click” beetles.
There are many species that damage peanut plants by feeding on the
underground parts. The “worm” stage is always found in
the soil, but finding them may be difficult. Wireworms may be noticed
during land preparation, but usually infestations are often first
noticed as the result of damage to pods. Depending on size, wireworm
damage can vary from small clean holes to large irregular holes.
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BENEFICIAL INSECTS
Insect pests are vulnerable to a vast array of natural enemies.
Control of insect pests by biological agents is the first line of
defense in a sound insect control strategy. Physically moving beneficial
organisms into a peanut field is not practical. However, avoidance
of practices that unnecessarily reduce beneficials will allow them
to work to their maximum potential. |
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VELVETBEAN CATERPILLAR
This insect is one of several caterpillars that often feed on peanut
foliage in the southern peanut-producing regions. Although easily
controlled with insecticides, this insect is a voracious feeder and
can do a great deal of damage in only a few days if not controlled.
Damaging populations are most commonly seen late in the growing season.
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