Pathogenicity of burrowing nematode, Radopholus similis (Cobb 1893) Thorne 1949 on banana

Abstract

Pathogenicity of the burrowing nematode,Radopholus similis on banana was studied at the College of Agriculture, Vellayani with three levels of population viz. 1000', 10,000 and 1,00,000 nematodes at five different growth stages of the crop starting from 45 days after planting and with 45 days interval. I t was observed that the general growth of the plant was retarded. The reduction was directly proportional to the initial inoculum used and the period of infestation. A reduction of 36*84 per cent was seen in the yield of plants inoculated earlier with 1,00,000 nematodes and as high as 60.52 per cent reduction in weight of the roots in the plants treated with 10,000 nematodes. Nematode population was found to reach its peak during the flowering season of the plant and decreasing thereafter. The multiplication of the nematode was observed to be inversely proportional to the Initial inoculum level. Population of even 1000 nematodes at active growth stage was enough to cause severe reduction in the plants growth. It was seen that plants could withstand the damage caused by the nematode feeding at later stages Le. after 180 days after planting. So the plants should be protected from the nematodes at earlier stages. The histological changes in the roots infested by nematodes revealed that the nematodes feed on the cortical tissue causing reddish brown lesions on the roots and nematodes could not enter the stelar region of the root even under severely infested conditions