Studies on the leaf spot diseases of oil palm (Elaeis guineensis jacq.) in Kerala

Abstract

A survey was conducted in the oil palm growing areas of Palode, Anchal, Kulathupuzha and Thodupuzha. Six leaf spot diseases were noticed. They include the leaf spots caused by Bipolaris hawaiiensis, Botryodiplodia theobromae, colletotrichum gloeosporioides, curvularia geniculata, fusarium pallidoroseum and phoma sorghina. All these are new records from India. Out of the six leaf spot diseases, the leaf spot caused by C.gloeosporioides was found to be the most severe causing damage in all the four plantations and it was considered to be of major economic importance. Other diseases recorded during the present investigation were of minor importance. Inoculation studies with six leaf spot causing pathogens showed that injury to leaves makes the plant more susceptible to leaf spot disease. The percentage of infection was more in injured leaves than in uninjured leaves. In invitro evaluation of fungicides showed that Bordeaux mixture, Dithane M-45 and Foltaf were effective, Bavistin controlled all the pathogens, except B. hawaiienis and C. geniculata. The leaf spot disease caused by C.gloeosporioides was observed in all oil palm plantations in Kerala in a serious proportion, especially during monsoon periods. Field evaluation of fungicides against the above disease indicated that Bavistin, Dithane M-45 Foltaf and Cuman L were effective.