EFFECTS OF INTERCROPS
ON DIAMONDBACK
MOTH(Plutella xylostella)
AND APHIDS (Bravicoryne
brassicae)ON
CABBAGE(Brassica oleracea
var. copen hagen )
BY:
STEPHEN E. MALOBA
A22/0043/2007
CROP PROTECTION MAJOR
SUPERVISOR: DORA KILALO
INTRODUCTION
 Cabbage is of great economic importance.
 Useful food for all classes of livestock and when
suitable varieties are grown, high value crops can be
produced for human consumption.
 Cabbage prefers moist, heavy soils and seasons with
plenty of rainfall. (Lockhart, 1983)
CABBAGE PRODUCTION IN KENYA
 The major cabbage growing provinces in Kenya
include Central and Rift Valley with 40% and 39% 0f
the total national production respectively.
 Average production from 2002- 2006 was 416,373.0
tons.
 A little quantity is exported.
Cont…
 Major constraints of production in Kenya are
-pests and diseases
–Diamond back moth(P. xylostella)
-Species of aphids – Brevicoryne brasscae,
Lipaphis erysymi and myzus pericae.
-Diseases-Black rot and soft rot
Problem statement
Diamond back moth is an important pest of
cruciferous crops.
 In its control, farmers tend to use insecticides
repeatedly which result in the development of
resistance to many common insecticides.
 Destruction of diamond back moth coupled with its
capacity to develop resistance rapidly has posed a
great challenge to farmers.

JUSTIFICATION
 Diamondback moth is known to have potential
capacity to develop resistance to pesticides in a short
period of time.
 The pesticides are able to affect negatively even
beneficial insects and also produce contamination
occurs.
Objectives
General objective
- To investigate the effects of intercrops in the
management of Diamondback moth and aphids in
cabbage.
Specific objectives
-To determine effective management of DBM and
aphids on cabbage by intercrops.
Hypothesis
-Intercropping is not effective in the management of
DBM and aphids.
MATERIALS AND METHOD
 The study was carried out at Kabete field station in a
complete randomized block design.
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T4
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Cont…..
Plots measuring 2x2metres(four replicates) were
used.
 Repellant plants used: spider plant, coriander and
onion
 Chemical used: Dimethoid
 Cabbage, the main crop was used as the control.
PARAMETERS COLLECTED
 Number of eggs on cabbage
 Number of larvae on cabbage
 Number of pupae on cabbage
 Damage scores in cabbage

RESULTS
Effects of intercrops on DBM
Treatment
Eggs
Larva
Pupa
Damage
scores
Spider plant
3 (82%)
1.13(80%)
0.45(89%)
0.63 (84%)
Corriander
7.75 (46%)
3.00(46%)
1.62(59%)
2.25 (43%)
Onions
5.33 (63%)
2.04(63%)
1.12 (71%)
1.38 (65%)
Chemical
10.08 (30%)
3.92(29%)
2.5 (10%)
2.96 (25%)
Control
14.33 (0)
5.5(0)
3.91 (0)
3.96 (0)
LSD
1.21
0.76
0.49
0.30
CV %
26.4%
47.3%
44.1%
23.2%
Effects of treatments on aphids population
Aphid population
35
30.62
30
25
19.6
20
15
17
13.75
14.75
10
5
0
Spider plant Corriander
Onions
Chemical
Contol
DISCUSSION
 I deduced that spider plants worked the best as a
result of its strong repellant smell against the DBM.
 Chemical control results were as observed probably
as a result of DBM’s resistance to the Dimethoid
used or ability to develop resistance rapidly.
 Aphids’ populations were not greatly affected by the
repellant effect of the intercropped plants hence,
their higher population.
CONCLUSION AND RECCOMENDATION
 Intercrops have an effect on DBM and aphids.
 Cleome gnandra is able to reduce the DBM and
aphids on cabbage more than Coriander dhania and
onions.
 Farmers to be advised to intercrop their cabbage
with spider plant.
 Farmers to limit the use of chemicals in the
management of DBM and aphids in order to preserve
environment, limit produce contamination and cut
down on the cost of production.
THANK
YOU