Browsing by Author "Thommen, K.J."
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Item Crop loss due to root (wilt) and leaf rot diseases and Oryctes infestation of coconut in the disease affected areas in Kerala, South India(2007-02-08) George, M.V.; Sukumaran, A.S.; Thommen, K.J.Root (wilt) and leaf rot are the major diseases seriously affecting the yield of coconut in Central and Southern Kerala. Of the. pests Oryctes rhinoceros L. is the most important, attacking the tender leaves and spathes. The root (wilt) disease affected areas on the west coast of India consist of seven districts of Kerala state viz. Ernakulam, Idikki, Kottayam, Alleppey and Quilon districts in full and part of Tricbur and Trivandrum districts where a survey was conducted using a multistage sampling procedure during 1971-76 to estimate the total production and the loss in coconut jield due to incidence of root (wilt) and leaf rot and Oryctes infestations. Among the 7 districts surveyed the total annual production of nuts was maximum in Alleppey district (406 million nuts). Ernakulam, Kottayam and Quilon districts produced annually 357 million, 337 million and 331 million - nuts respectively. The average yield per palm was found to be very low in the severely disease affected districts (Alleppey 31 nuts, Kottayam 32 nuts and Idikki 35 nats). the average yield of a healthy palm fr«e from disease and Oryctes infestation was also high in Trichur (61 nuts) and Ernakulam (60 nuts) districts. The loss in yield was estimated to be about 75% for trees in the advanced stages of the disease and 25 to 50% in the early stages. The loss due to Oryctes infestation was found to vary from 1 to 6 nuts per palm in different districts. The loss of nuts due to disease and pest was maximum in Kottayam district (125 million nuts annually) followed by Alleppey district (113 million nuts). In Quilon and Ernakulam districts, loss due to disease and pest was 73 million and 58 million nuts respectively. In Trivandrum an:l Tricbur districts the total loss was only 14 million nuts and 8 million nuts respectively. The overall loss of production due to the diseases and Oryctes was estimated at 419 million nuts which would amount to 20% of annual production in the disease affected tract.Item Crop loss due to Root (wilt) and Leaf Rot Diseases and Oryctes Infestation of Coconut in the disease affected areas in Kerala, South India(1985-01) George, M.V.; Sukumaran, A.S.; Thommen, K.J.Root (wilt) and leaf rot are the major diseases seriously affecting the yield of coconut in Central and Southern Kerala. Of the pests Oryctes rhinoceros L. is the most important, attacking the tender leaves and spathes. The root (wilt) disease affected areas on the west coast of India consist of seven districts of Kerala state viz. Ernakulam, Idikki, Kottayam Alleppey and Quilon districts in full and part of Trichur and Trivandrum districts where a survey was conducted asing a multistage sampling procedure during 1971-76 to estimate the total production and the less in coconut yield due to incidence of root (wilt) and leaf rot and Oryctes infestations. Among the 7 districts surveyed the total annual production of nuts was maximum in Alleppey district (406 million nuts). Ernakulam, Kottayam and Quilon districts produced annually 357 million, 337 million and 331 million nuts respectively. The average yield per palm was found to be very low in the severely disease affected districts (Alleppey 31 nuts, Kottayam 32 nuts and Idikki 35 nuts). The average yield of a healthy palm free from disease and Oryctes infestation was also high in Trichur (61 nuts) and Ernakulam (60 nuts) districts. The loss in yield was estimated to be about 75%- for trees in the advanced stages of the disease and 25 to 50% in the early stages. The loss due to Orycles infestation was .found to vary from 1 to 6 nuts per palm in different districts... The loss of nuts due to disease and pest was maximum in Kottayam district (125 million nuts annually) followed by Alleppey district (113 million nuts). In Quilon and Ernakulam districts, loss due to disease and pest was 73 million and 58 million nuts respectively. In Trivandrum and Trichur districts the total loss was only 14 million nuts and 8 million nuts respectively. The overall loss of production due to the diseases and Oryctes was estimated at 419 million nuts which would amount to 20% of annual production in the disease affected tract.Item Incidence of Root (Wilt) and Leaf Rot Diseases and Oryctes Infestation in Kerala(2007-02) George, M.V.; Thommen, K.J.; Sukumaran, A.S.The root (wilt) disease affected coconut areas in Kerala were surveyed adopting a multistage sampling procedure during 1971 - 76 to estimate the percentage of palms affected by root (wilt) and leaf rot diseases and infested by Oryctes. The incidence of disease was maximum in Alleppey district (54%) followed by Kottayam (50%) and Idikki (43%) districts and minimum in Trichur district (less than 5%) where the disease incidence was limited to the southern villages. The Oryctes infestation was as high as 75 % in Quilon district and 70 % in Alleppey district. It is the lowest in Trichur district (39 %). In other districts the infestation varied from 59% to 66%. The association of Oryctes infestation with these diseases was also discussed.Item Studies on the anatomical changes in the tissues of the coconut palms affected by wilt (root) disease : I. A note on the changes in the mesophyll(1959) Shanta, P.; Thommen, K.J.; Menon, K.P.V.In the coconut palm, affected by the Wilt (Root) disease, different types of chlorosis of leaves, often accompanied with flaccidity are met with. No change is noticed in the size, shape and arrangement of cells of the mesophyll which is attributed to the comparatively late appearance of chlorosis in mature leaves. However, the chloroplastids are found to be highly affected, the desintegration and degeneration of which result in the partial or complete disappearance of the chlorophyll.Item Varietal Resistance Studies(2007) Sethumadhava Menon, K.; Sukumaran, A.S.; Thommen, K.J.