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Wireworms
Wireworms
are the larvae of click beetles. Female adult click beetle lay eggs near
grassy patches. The eggs hatch in the soil where the larvae feed on grass
roots. The larvae remain in the soil from two to six years rarely moving
far from where they hatched.
Wireworm larvae cause corn crop damage in two different ways. First, they
will feed on planted seeds. Wireworms may eat only a portion of the seed
or hollow out the seed completely. This results in germination failure
or weakened seedling vigor. Secondly, after the corn plant has emerged,
the damage is primarily in the form of wireworms tunneling into the underground
portion of the stalks. Plants are rarely cut off completely, but early
tunneling is often severe enough to cause plant death. Once a stand has
been firmly established, wireworms feed primarily on small roots.
Wireworms are traditionally thought of as only being a pest in crops following
a long-lived grass stand such as CRP acres. This situation is at a high
risk of wireworm damage due to the habitat preference of wireworms. Since
the larval stage lasts for multiple years, crops following grass may be
at risk for more than one year. In recent years however, wireworm damage
has been observed to be on the increase in continuous crop production,
particularly corn.
There are several possible explanations for this observation. More and
more land that has been set aside as non-crop area is coming back into
production. Less area is in undisturbed sod and the beetles are laying
eggs in areas that previously had been infested only lightly. Any crop,
which in some way resembles the native habitat of the wireworm, is apt
to become alternate sites of wireworm infestation. Corn, being a vigorously
rooted grass crop, is a possible wireworm food source.
No-till and ridge-till systems are also more prone to wireworm infestations.
The increased residue level associated with these systems promotes good
soil structure and favorable moisture conditions, which are also favorable
to wireworms. Tillage brings some wireworm larvae to the soil surface
where they are susceptible to desiccation. With reduced tillage systems,
the opportunities to kill wireworms in this way are reduced or eliminated.
Grass weeds can be patchy and difficult to control in corn. Grassy weed
patches are an egg-laying haven to female click beetles. Any area that
has had a recent grass stand or grassy patch will be at risk of wireworm
damage in following years.
Both chemical and cultural methods can be utilized in the management of
wireworms. Avoid planting corn after a sod crop whenever possible. Plant
when soil moisture and temperature is favorable for prompt germination.
The faster the crop can germinate and become established, the less likely
it is that wireworms will cause significant damage.
Where
wireworm infestations are likely to be high, the combination of a planter
box applied insecticide with a soil-applied insecticide will be of benefit.
The planter box insecticide will protect the seed until it germinates.
The soil-applied insecticide will give residual control through the period
of stalk tunneling.
The following tables are lists of insecticides labeled for control of
wireworms. These tables are not a complete listing of all insecticides
labeled for control. The inclusion or omission of a chemical is not intended
as endorsement or disapproval. This is merely a guide. Consult your local
chemical dealer, extension agent, or professional seedsman for a specific
recommendation for your area.
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Product
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Active Ingredient
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Use Rate
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Application
|
|
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(product/1000
row ft)
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Aztec
2.1 G
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tebupirimphos
+
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6.7
oz.
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band,
T-band
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|
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cyfluthrin
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in-furrow
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Force
3 G
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tefluthrin
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4-5
oz.
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band,
T-band
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|
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in-furrow
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Fortress
2.5 G
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chloethoxyfos
|
6
oz.
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T-Band
|
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in
furrow
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Lorsban
15 G
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chlorpyrifos
|
8
oz.
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T-Band
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in
furrow
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Thimet
|
phorate
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8
oz.
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band
only
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Table 1. Insecticides registered
for wireworm control in corn.
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Product
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Active
Ingredient
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Use
Rate
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(product/1000
row ft)
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Agrox
DL plus
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15%
Captan + 15% diazinon
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3.6
oz/cwt
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+
25% lindane
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Germate
Plus
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14%
carboxin + 15% diazinon
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2 oz/bu, or
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+
25% lindane
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1.5
oz/42 lb
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Kernel
Guard
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14.7%
captan + 15% diazinon
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2 oz/bu, or
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+
25% lindane
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1.5
oz/42 lb
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Kernel
Guard Supreme
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10.4%
permethrin +
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1.5
oz/42 lb
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carboxin
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Nugro-Isotox
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12.5%
captan + 25% lindane
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3 oz/bu
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Sorghum
Guard
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32.5%
captan + 16.6% lindane
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8
oz/cwt
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|
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(cwt
= 100 lb)
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Table 2. Planter box applied
insecticides labeled for control of wireworms.
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