Direct estimation of maize crop losses due to stem borers in Kenya, preliminary results from 2000 and 2001 - Nairobi (Kenya) KARI|CIMMYT : 2002 - p. 401-406 - Printed
Maize is the major food crop in Kenya, where 2.4 million tons are produced yearly for 28.6 million people (85 kg/person). Population is growing rapidly (2.9%/year) and the increased population pressure on the land has resulted in increased pest pressure on crops. Stem borer is one of the most important pests of maize. Previous research with artificial infestation established clear links between incidence or damage factors and yield losses These results cannot be extrapolated to estimate crop losses under natural infestation, although it is precisely those estimates that are needed in order to estimate impact and to set research and extension priorities. Therefore, to estimate the potential impact of the Insect Resistant Maize for Africa (IRMA) project, a representative sample of maize fields was selected during 1999 and 2000 for each of Kenya's 5 major agro-ecological zones. Half of each field was protected against stem borers using a systemic insecticide, and the other half was left for natural infestation, and the comparison of yields gives an estimate of crop loss. Total loss in Kenya due to stem borers is thus estimated at 13.5 % (valued at between US$25 and US$ 59.8 million), ranging from 11% in the highlands to 21.% in the dry areas. More than half of the losses occur in the moist transitional zone. This area also has a high adoption rate of improved varieties (95%) making this area a promising target for insect resistant varieties. In the dry areas, losses are relatively high (21%), but its low yields reduce potential benefits but those benefits would go to more resource-poor farmers.