RESISTANCE IN GROUNDNUT GENOTYPES TO KALAHASTI MALADY CAUSED BY THE STUNT NEMATODE, TYLENCHORHYNCHUS-BREVILINEATUS

A severe nematode disease of groundnut, popularly called 'Kalahasti ma lady', caused by the nematode Tylenchorhynchus brevilineatus, has been prevalent since 1976 in certain parts of Andhra Pradesh, India. A tot al of 1599 groundnut germplasm accessions and breeding lines were scre ened for resistance to the nematode disease in replicated trials on a farmer's field in a disease hot spot location during 1985-6. Twenty-th ree genotypes were identified as resistant and they had disease scores of 2.0 or less on a 1-5 disease scale. Of these, 14 genotypes were co nfirmed to be resistant in advanced screening trials in the 1986 rainy and the 1985/6 and 1986/7 post-rainy seasons. Resistance to the nemat ode was stable in all three trial sites in the 1986/7 post-rainy seaso n. Most of the resistant genotypes have undesirable pod/seed character istics. One of the resistant genotypes is a high-yielding breeding lin e (TCG 1518) and this is being released for use in disease-affected ar eas of Andhra Pradesh State.