Diamondback moth (DBM) is a major insect pest of cabbage, kale, broccoli and canola. Moths are grey and about 8.5 mm long. The DBM derives its name from the white markings along the back of the forewings which when folded form a diamond shaped pattern. Larvae wriggle violently if disturbed and drop from the leaf suspended by a silken strand. DBM populations increase in dry conditions, especially in the presence of favorable crop and/or weed hosts.
DBM larvae feed on leaves from the underside and leave tiny "windows". The caterpillars first attack the outer leaves of the young plants and subsequently attack developing cabbage heads leaving entry points for pathogens. The moths lay eggs singly or in groups of two or three on the leaves. Eggs are small, nearly round and yellowish. The larvae are light green and pointed at each end. Their bodies are covered by tiny, erect black hairs.
|Healthy cabbage head||Healthy cabbage seedlings||Cabbage leaves severely damaged by Diamondback moth and showing tiny “windows” symptom|
1. Scout fields weekly for Diamondback moth larvae.
2. Raise seedlings in protected nurseries to avoid infestations.
3. Rotate cabbage with nonâ€susceptible hosts.
4. Destroy infested crop residues and weed hosts around cabbage/kale fields.
5. Use insecticides containing Bacillus thuringiensis (Bt) such as Thuricide in combination with a wetting and sticking agent such as Silwet (oganosilicone 80% w/w + polyalkyleneoxide 20% w/w).
6. Use agronets as physical barriers to prevent DBM infestations in the field.
Note: Agroâ€chemicals should be used in consultation with professional practitioners and considering existing cautionary/safety measures, particularly the manufacturer’s instructions
Reference Links Infonet: http://www.infonetâ€biovision.org/default/ct/90/pests
Compiled by: Nyasani J.O., Anyango J.J., Kasina J.M. and Tuey R
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