INVESTIGATION ON THE CLONAL SUSCEPTIBILITY OF POWDERY MILDEW DISEASE IN RUBBER PLANTATIONS IN MEENACHIL, KANJIRAPPALLY AND PEERMEDU TALUKS OF KOTTAYAM AND IDUKKI DISTRICTS - K AUGUSTHY LUKA; Dr. K JAYARATNAM (COLLEGE OF HORTICULTURE VELLANIKKARA DEPARTMENT OF PLANTATION CROPS AND SPICES, 1991)