Abstract:
Kale (Brassica oleracea var.acephala) is an important source of income to many small-scale
farmers in Kenya and is a major dietary component for many Kenyans. The production of kale is
however constrained by several pests among which kale aphid is one of the major insect pests.
The use of pesticides has resulted to problem of pest resistance, loss of beneficial insects such as
ladybird (biological agents) and pollution. The experiment attempts to investigate on alternative
methods mainly cultural control. Bulb onion (Tropicana hybrid variety) was intercropped with
kale, thousand headed variety. The experiment was laid out in a randomized complete block
design with four treatments replicated thrice. The treatments were: treatment one (sole kale cropcontrol),
treatment two (kale+ onion + manure), treatment three (kale + onion), treatment four
(kale + manure). Data on aphid counts, percentage kale fresh leaf weight and kale leaf damage
was collected from third week to sixth week after transplanting. The data was analyzed using the
Genstat software and mean separation was done using the less significant difference. The aim of
the study was to determine the effect of intercropping kale with onions and application of
manure on aphid population densities, kale leaf damage and yield of kale. Intercropping kale
and onion both with and without manure significantly reduced (P<0.05) aphid densities and
damage on kale leaves compared to kale monocrops with and without manure. The lowest aphid
densities and damage on leaves were recorded in kale- onion intercropping with manure
application. Moreover, significantly higher marketable leaf weights were recorded in kale
monocrop with the application of livestock manure as compared to kale monocrop without
manure application. The present study concludes that intercropping kale and onion with
application of manure in managing aphids and improving kale yield is most effective as
evidenced by lowest aphid densities, lowest leaf damage and highest percent marketable leaf
weight. It is recommended that the study be repeated for another season to confirm the results of
this study.
