MANAGEMENT OF DIAMONDBACK MOTH*
Management of Diamondback moth populations depends on culture
practices, the use of chemical and biological sprays and
monitoring. A host-free period can help to reduce Diamondback
moth levels after final harvest of the current season's crop;
the longer the host-free period, the greater the reduction in
Diamondback moth population. A host-free period is when old
plantings have been disked under and other infestation areas
such as greenhouse seedlings or alternate hosts have not been
present to support Diamondback moth populations. All crop
residue should be disked to a depth of at least 2 to 4 inches,
immediately after harvest is complete, to destroy larval food
sources and pupae in the soil. Wherever possible, destroy
infested crops before a new crop is planted in adjacent fields.
Transplants also must be checked before planting as field
infestations can occur from infested transplants. This product
may be used in an IPM program in conjunction with insecticides
in areas of high pressure, where migration from adjoining
fields is occurring, or where control of secondary pests is
needed.
*Integrated Pest Management for Cole Crops, University of
California
See Suterra's Product Table here...
DIAMONDBACK MOTH BIOLOGY:
Diamondback larvae are small (about 0.33 inch when full grown)
compared to other caterpillars in cole crops. The larval body
is wider in the middle and tapering at both ends with two
pro-legs on the last segment forming a distinctive V-shape at
the rear end. When disturbed the larvae wiggle frantically or
rapidly attach a silken line to a leaf and drop over the edge.
They feed mostly on outer or older leaves of older plants
chewing out small holes or at the growing points of young
plants. They will also feed on floral stalks and flower buds.
Larvae mature in 10 to 14 days and spin a loose cocoon on
leaves or stems for pupation. Moths lay their tiny, roundish
eggs singly on the undersides of leaves; eggs are difficult to
find. Although they may occur all year round diamondback moths
are often abundant in spring and early summer and populations
may rise again in fall.
DAMAGE:
Diamondback moth infestations are most serious when they damage
the crowns or growing points of young plants or Brussels
sprouts. This injury can severely stunt growth. Sometimes
diamondback moth caterpillars may also bore into heads of
broccoli or cauliflower, or in the flower buds of stalks,
causing economic injury and contamination. Injury to leaves is
not usually serious, except when the wrapper or cap leaves of
cabbage are injured.
BIOLOGICAL CONTROL:
Natural enemies can provide some control of Diamondback moth. In Southern California, the ichneumonid wasp, Diadegma insularis, has been identified as the most common parasite. Trichogramma pretiosum may also attack diamondback eggs. Microbial diseases are not known to be a significant mortality factor.
