3.1.20
ON-FARM EXPERIMENTS TO TEST A WEATHER-BASED ADVISORY SYSTEM FOR CONTROL OF GROUNDNUT LEAF SPROUTS

RK REDDY1, DR BUTLER1, H LANTING 2, K RAMA DEVI2 and B SREENIVAS3

1Pathology Unit, International Crops Research Institute for the Semi-arid Tropices (ICRISAT), PO Patancheru 502 324, AP, India; 2Agriculture Man Ecology (AME), PO Box 7836, 368, 4th Cross, JP Nagar, Bangalore 560 078, India; 3Acclon Fraterna (AF), Bangalore Highway, Anantapur 515 00, AP, India

Background and objectives
Leaf spot diseases of groundnut, caused by Phaeoisariopsis personata and Cercospora arachidicola are widespread in India; however, in rainfed conditions the severity of disease varies with location and season. Resource-poor farmers in developing countries do not usually apply fungicide to control foliar diseases in rainfed groundnut. To determine the need for fungicide to control these diseases, and to achieve optimal timing of applications, the weather-based advisory system (WBAS) considers the availability of inoculum and the extent to which environmental conditions favour infection. Central to the system is a requirement for the daily total period of leaf wetness, and we designed a simple instrument with a leaf wetness sensor to record accumulated hours of wetness. The instrument, referred to as a leaf wetness counter, is inexpensive and is suitable for use on remote sites.

Results and conclusions
On-farm experiments were carried out by farmers in six villages in the south of Andhra Pradesh over two growing seasons, using one leaf wetness counter in each village, shared between six farmers. The experiments showed that in one season, substantial increases in pod and haulm yield were achieved with only one or two fungicide applications. Overall increases in yield of 25% for pods and 35-40% for haulms were achieved. In the other season, the advisory system indicated that no fungicide was necessary for leaf spot control.

< b>References
1. Alderman SC, Beute MK, 1986. Plant Pathology 76, 715-719.
2. Butler DR, Wadia KDR, Jadhav DR, 1994. Plant Pathology 43, 112-120.