Global Theme on Agroecosystems
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Global Theme on Agroecosystems
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Pigeonpea (Cajanus cajan) is one of the most important grain legume crops, and is a source of inexpensive protein in the tropics and subtropics. This crop is adaptable in a number of cropping systems and is grown on marginal to rich lands. It is cultivated over 4 million hectares mostly in southern Asia and eastern Africa providing grain, fodder and fuel. Pod borer is the major constraint to pigeonpea production although there are more than 200 species of insects known to live and feed on this crop. Pigeonpea crop losses due to Helicoverpa can range from 20-100% on farmers' fields and are estimated to add up to more than US$310 million annually worldwide. Inappropriate use of insecticides has led to development of resistance, creation of secondary pests, loss in bio-diversity, and increase in human health hazards. Recent crop surveys indicate that before 1975 only 20% of the pigeonpea farmers were using insecticides; but by 1993, 100% used chemical control in India. Application of three to six sprays of chemicals was common practice on pigeonpea on calendar basis to protect the crop from pod borers. Screening germplasm for resistance against pod borers though indicated occurrence of resistance, but it is not adequate to cater to the needs of our clients. To sustain productivity of pigeonpea-based systems with minimal adverse affect on the environment, ICRISAT scientists have taken up multi-disciplinary multi-organizational on-farm participatory research project in collaboration with governmental, non-governmental, state agricultural universities and farmers. This IPM project which was launched in 1997 currently concentrating on location-specific refinement of technologies to minimize dependency on external agencies in the area of IPM in southern Asia (India, Nepal and Bangladesh). This project concentrates on the manipulation of farming systems to minimize pest infestation (cultural), enhanced natural control processes, and selective use of bio-rational and synthetic pesticides. Among various components of IPM this project paid much attention to indigenous technologies that were shelved by farmers in preference to chemical insecticides. Farmers in Gulbarga district of Karnataka state, (Rangareddy), and (Mahabubnagar districts) in Andhra Pradesh, India, used indigenous methods such as shaking off (Helicoverpa Larva) from the plants to manage the pod borer until chemical insecticides were introduced in the early 1970s. They soon realized that spraying of chemicals was easy and effective compared to their previous traditional method. This worked out well for some years. Later, the total dependence on chemicals resulted in high investments followed by declining yields in the crops. At this stage, the farmers were forced to think of alternatives to chemicals. A solution was to return to the old traditional practice. With their past experience in pest management, the farmers brought back their old traditional technology to tide over the crisis. This technology involves the collection and removal of pests from their feeding sites. After crop pollination and pod set, when 1-2 larvae plant-1 are noticed, three farmers enter the pigeonpea field, one to hold/drag a polyethylene sheet on the ground, while the other two shake the plants. This gentle shaking can dislodge most of the caterpillars from the plants. These dislodged larvae are collected in a sack and destroyed.
FARM TO LABORATORY Normally technology moves from laboratory to farmers, but after seeing the convincing results in farmers' fields this technology was brought to ICRISAT research station during the 1998 season to save the research trials when there was unsatisfactory pest control with initial chemical applications. Crops infested with the pests did not have satisfactory results even after 6 insecticidal sprays between 127 and 160 days after sowing (DAS). On the other hand, larval population increased from 1 larva plant-1 at 134 DAS to 7 larvae at 160 DAS. However, when those very plants were shaken at this stage an 85% reduction in the insect population was achieved while the larval population in adjacent chemical sprayed plots remained higher than the threshold level (2 medium sized larvae plant-1) through out the cropping period (Figure 3).
Figure 3. Effect of chemical and plant shaking on pod borer, Helicoverpa larvae in pigeonpea at ICRISAT during 1998-99. After crop pollination and pod set, detailed observations were taken on number of flowers, pods and Helicoverpa larvae on 50 randomly selected plants at ICRISAT-Patancheru before and after the shaking operation. These Studies indicate that 97% larval drop along with 3% healthy flowers and 1% good-pod drop. Though several flowers and pods were noticed on the collection sheet most of them were dried and damaged. Three persons can easily cover 0.4 ha in a day. This operation is repeated twice or thrice in case of further infestation. Thus, this technology provides effective pest control with substantial saving on chemicals and minimizes environmental pollution induced through chemicals. This technology, initiated at a few locations during 1997, rapidly spread to more than 100 villages involving several thousand farmers in three states of southern India within two years. All these farmers continue to use the method. This technology allowed natural enemies, particularly birds to settle in this area, a development instrumental in keeping adjoining chickpea crops free from pod borers and resulted in saving on the cost of 3-4 chemical sprays. Thus, this simple cultural control helped not only in saving the pigeonpea crop but also reduced the inputs of insecticides. The spillover effects on adjacent chickpea crops were evident. This has clearly shown the importance of two-way information flow (both from laboratory to farm and farm to laboratory) for effective implementation of IPM projects. This simple technology can be implemented by all family members and is gender neutral. The economics of this technology were worked out as presented below.
Direct impact
Indirect impact
ACKNOWLEDGEMENTS This research is supported by IFAD (TA Grant No: 330) and is implemented in collaboration with ICAR, ANGRAU, MAU, and NGO and farmers. For further details you may contact:
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