FACTSHEETS FOR FARMERS
www.plantwise.org
Created in
Vietnam
,
November
2012
Diamondback moth (DBM) and its management
Recognize the problem
In Vietnam, the diamondback moth (DBM) is a pest of crops such as cabbage
and Chinese mustard. The caterpillar feeds on the leaves of the plant, making
holes in them. If left untreated, DBM caterpillars can rapidly increase in number
and cause severe damage to the crop.
Background
The newly hatched caterpillar tunnels the leaf and after a few days becomes a
surface feeder. Their size varies, but when fully grown the caterpillars reach
about 10 mm long. They are usually found on the lower surface of the leaf.
The adult moth is about 7 mm long and has a diamond shaped pattern on the
wings which can be seen from above (Picture 1). The eggs are white and are
laid mainly on the lower side of the leaf. In Vietnam, the moth can have about
10 generations per year.
Management
•
Plant cabbage between tomato to repel adult moths (Picture 2)
•
Remove old leaves from the crop as this is where the moth lives before it
grows into an adult
•
Observe the field for moths which usually fly in the early morning and
late evening. If lots of moths are seen then look carefully at the crop to
see how many caterpillars there are
•
Pheromone and yellow sticky traps, if available, can also be used to
monitor the presence of adults. To use these traps, please consult your
extension agent or dealer.
•
Use chemicals only when necessary, so that you protect the good insects
(natural enemies) in the field. To know which insects are good insects,
check with your government extension agent. To decide whether to use
chemicals or not, follow these guidelines:
◦
caterpillar number less than 1 per plant - do not use any chemical
◦
caterpillar number from 2 to 5 per plant
use Bacillus thuringiensis (e.g. Dipel) or other plant based sprays
(neem)
◦
caterpillar number more than 5 per plant - spray
recommended chemicals (e.g. cypermtherin, abamectin,
emamectin)
Scientific name(s)
>
Plutella xylostella
The recommendations in this factsheet are relevant to
:
Vietnam
Authors
:
Dung Nam Ham
Plant Protection Sub Department
tel:
0988163070
email:
NAMBVTVHY@GMAIL.COM
Edited by
Plantwise
Plantwise is a global initiative led by CABI
VN001En
Lose Less, Feed More
Picture 1: DBM adult.
(Photo by A.
Sivapragasam)
Picture 2: Intercropping of cabbage
and tomato.
(Photo by A.
Sivapragasam)
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.
