FACTSHEETS FOR FARMERS
www.plantwise.org
Created in
Kenya
,
December
2012
Diamondback Moth on Brassica
Recognize the problem
Young diamondback moths are pale green caterpillars. They feed by eating the
lower side of the leaf leaving a see-through hole mostly referred to as a
'window'. They are small compared to other caterpillars. The adult moths have
3
diamond shapes on their wings hence the name of the pest. The females lay
small yellow eggs on the leaves. These hatch into green caterpillars with no
markings. When fully grown, the caterpillars grow inside a whitish silk cocoon
attached to leaves or stems.
They are most serious when they damage the crowns or growing points of
young plants. This injury can severely stunt growth, keeping the plant small.
Background
The numbers of caterpillars can increase rapidly during dry weather and
decrease in rainy conditions. Overhead irrigation and heavy rains tend to wash
off young caterpillars. Large numbers in the field, if uncontrolled, can destroy
the crop.
Management
Non-chemical control
•
Conserve natural enemies such as parasitoids, ground beetles, true bugs,
syrphid fly larvae and spiders, which can eat or kill the diamondback
moth. Supply flowering plants to serve as a food source for adult
syrphids. Avoid spraying pesticides when there are enough natural
enemies in the field to reduce caterpillar numbers.
•
Interplanting Brassica crops with tomato or pepper can repel the
diamondback moth.
•
Monitor the crop with yellow sticky traps or pheromone traps to discover
the pest early for easy control.
•
Planting during the rainy season and use of overhead irrigation can help
control the larvae.
•
Use biological pesticides like
Bacillus thuringiensis
(Bt) and
Beauveria
bassiana
.
Chemical control
•
Use chemicals such as Indoxacarb, Lufenuron, and Methoxyfenozide.
Scientific name(s)
>
Plutella xylostella
The recommendations in this factsheet are relevant to
:
many countries where this pest or problem is present
Authors
:
This factsheet is based on information written for "The Brassica Farming
Handbook", first published by KENGAP Horticulture 2011.
Kengap Horticulture Ltd, P.O Box 12898-00400 Nairobi, Kenya
tel:
+254 722 575544; +254 723 491549
email:
books@kengap.co.ke;
www.kengap.co.ke
Edited by
Plantwise
Plantwise is a global initiative led by CABI
031En
Lose Less, Feed More
Diamondback moth caterpillar.
(Photo by Kengap Horticulture)
Diamondback moth adult.
(Photo
by Russ Ottens, University of
Georgia, Bugwood.org)
When using a pesticide, always wear protective clothing and follow the instructions on the product label, such
as dosage, timing of application, and pre-harvest interval.
