BLACK
CUTWORM
Identification &
Incidence: Loss of stand prior to emergence or due to above ground
cutting or below ground tunneling injury indicates presence of black cutworms,
which are dark colored larvae with minimal markings ranging in size from 1/2
inch to 2 inches in length. Incidence of black cutworm injury increases as tillage
is reduced and when broadleaf weeds are abundant prior to planting.
Adult
Larve
Above ground plant cutting damage
Below ground damage
Sampling & Assessment:
Cutworm infestations may be detected early by periodic inspection of stand for
injury following initial emergence of corn. If injury is detected, stand counts
should be taken to determine percent of stand injury and loss, and a number of
cutworm larvae should be collected to determine the predominant stage of larval
development. If corn is in the 2nd or 3rd leaf stage, an additional 3 or 4 plants
may be affected for every plant exhibiting fresh injury. If corn has reached the
5th or 6th leaf stage, additional stand injury will be minimal. Rescue treatment
should be based on estimated additional stand loss. Management Options:
Reduced tillage or no-tillage fields with substantial broadleaf weed infestations
may warrant preventive treatment (see soil insecticide
chart or foliar insecticide chart). If preventive
treatment is not applied, rescue treatment may be applied if severe infestations
are detected early. Early tillage and good weed control will reduce incidence
of cutworm infestation.
Corn,
Soybean, Wheat, and Alfalfa Field GuideBulletin 827