Stalk borer (aka common stalk borer) damages corn seedlings and small plants up to about the eight to 10 leaf stage; larger plants are attacked but generally tolerate the injury. This insect has a very broad host range, infesting many weeds and some cultivated plants. Eggs over-winter on weeds (usually grassy weeds) and larvae hatch around corn planting time. Once larvae get too big to tunnel small stemmed plants they crawl to larger stemmed hosts. Corn and large stemmed weeds (e.g. dock, cockleburr) meet their needs. The caterpillars tunnel into the side of corn plants or enter the plant through the whorl. Tunneled plants are partially cut-off from within and quickly die or develop "dead heart". On a per plant basis damage can be very severe but infestation is usually confined to the field edge rows. However, in no-tillage situations where grass hosts are available to the egg laying moths in early fall, spring infestation may be scattered thorough out the field. There is one generation per year.
Management of stalk borer is seldom necessary. However, the pest does respond to rotation and management of grassy weeds immediately surrounding and within fields to be planted to corn. In fields to be no-tillage planted, management of grasses in the preceding season can reduce infestation. Infestations are usually discovered too late to remove larvae from within the plants by spraying insecticide.
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