Integrated management of groundnut rosette disease
Abstract
Groundnut is an important food, feed and cash crop in sub-Saharan Africa. This crop
suffers greatly from a viral disease; groundnut rosette (GRD) vectored by an aphid
cause 100% yield loss if it occurs before flowering. Management strategies for the
disease include reduction of vector populations using pesticides, cropping practices to
delay onset and spread of both vector and the disease and growing groundnut varieties
resistant to the virus and the vector. The objective of this study was to assess the
effectiveness of selected cultural practices, chemical pesticide and host plant
resistance in the management of groundnut rosette disease. Field experiments were
conducted between March 2007 and February 2008 at Siaya Agricultural Training
Centre (Siaya district) and Kenya Agricultural Research Institute, Alupe sub station
(Teso district) in Western Kenya.
The cultural disease management strategies included alteration of time of planting
(early planting at the onset of rains and late planting one month later), host plant
resistance, use of trap crops (cowpea and sesame), vector control using a chemical
insecticide (dimethoate) and roguing. The experimental design used was randomized
complete block laid out as a split-plot and replicated three times. The disease
management practices and groundnut varieties were allocated to main plots and subplots
respectively.
The time of planting significantly influenced aphid population and groundnut rosette
disease incidence. High aphid population and GRD incidence was observed in lateplanted
than in early-planted groundnut. Late planting reduced groundnut yield by 48-
71%. Application of dimethoate lowered vector population and reduced GRD
incidence by 85-94%. Cowpea and sesame trap crops reduced the disease incidence
by 56-76% while roguing reduced the disease incidence by 30-44%. Groundnut yield
increased by 167-255% where insecticide and trap crops were applied. Planting of
varieties resistant to the virus (ICGV-SM 90704) and the vector (ICGV 12991)
reduced the disease incidence by 46-61%. Aphis craccivora Koch was the most
abundant of the aphid species. This study recommends early planting in addition to
combination of host plant resistance with other protective measures such as cultural
practices for effective management of groundnut rosette disease. There is however, a
need to undertake further studies in order to establish economic injury levels and
action thresholds to guide in integrated management of groundnut rosette disease and
its vectors.
Citation
Master of Science degree in Crop ProtectionPublisher
University of Nairobi Department of Plant Science and Crop Protection