Disease-resistant pigeonpeas

Wilt and sterility mosaic are two devastating diseases of pigeonpea. Wilt is caused by a fungus which blocks the water conducting tissues of plants, causing plants to wilt and then ultimately to die. Sterility mosaic prevents the formation of flowers and pods, causing the plants to be sterile. Both diseases create major problems in Kenya, Malawi, Tanzania and Uganda as well as in South-east Asia and total crop losses are estimated to be over US$300 million annually. Although pigeonpea lines resistant to each disease have been developed in the Fast, identifying a variety resistant to both has, until recently, proved elusive. Plant breeders at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), in collaboration with the national research system of India, have now come up with a resistant variety which they call ICPL 87119. ICPL 87119 has the large brown seeds that consumers prefer, and it matures in only four months: but its real advantage is that it is resistant to wilt and sterility mosaic. Trials in a wilt screening nursery at the ICRISAT Centre between 1989 and 1991 resulted in a mean disease incidence of only 2% (compared with 56% for the national control and 97% for the susceptible control). Similar results were obtained for resistance to sterility mosaic with 2.3% incidence (compared with 100% for both controls). During the same period the variety was tested m the central and southern zones of India by the All-lndia Coordinated Pulses Improvement Project. In the central zone, yields were 20% higher than that of the control. Preliminary experiments in Venezuela have shown similar results. Scientists believe that farmers could achieve similar production results from ICPL 87119 when crown in comparable agroecological zones elsewhere. ICRISAT Patancheru Andhra Pradesh 502324 INDIAWilt and sterility mosaic are two devastating diseases of pigeonpea. Wilt is caused by a fungus which blocks the water conducting tissues of plants, causing plants to wilt and then ultimately to die. Sterility mosaic prevents the formation of..