Population Dynamics Of Nematode Parasites And Evaluation Of Damage By Meloidogyne Javanica To Some Common Vegetables In The Kenya Highlands

Abstract

The commonly cultivated vegetables in the Kenya Highlands include tomato, capsicums cucumber, carrot, cabbage and dodo (Amarathus sp), They form an important component of the human diet particularly in the small-scale farming communities. Depending on the species either the leaves, fruit, seed, stem or roots are the edible parts.world production figures for many vegetables are not available probably because comparatively small amounts of "That is produced reach the markets where quantification would be made. East Africa's vegetable production in 1970 was estimated to be approximately 20 million kg. worth a substantial sum of money (Kenya Dep, Agric. Annual Reports, 1956-1970; The Economic Review of Kenya Agricuture Vol. 4, 1972; Uganda Dept. Agric. Annual Reports 1908-1971; Tanzania Dep, Agric. Annual Reports, 1960-1967). Due to increased demand for these crops a number of individuals and private companies in E. Africa have engaged in large-scale production particularly of beans, capsicums, okra, brinjals, courgettes, tomato, cabbage, carrots, lettuce and cucumber. Some of the constraints in vegetable production have been found to be attacks by insects, diseases caused by fungi, bacteria, viruses and plant parasitic nematodes. Wallace (1963), Dropkin (1969) and webster (1969) have revieved reports on cellular responses of plants to nematode infections Nematodes normally attack the roots of plants including vegetables. The salivary secretions they inject into the plant cause biochemical injury and this results in two distinct effects in hosts. Cells directly invaded develop giant cells (syncytia) on which the invading parasite feeds. Adjacent cells which the nematode does not use as food but which because of secretions or excretions from the parasite produce cell hyperplasia and hypertrophy. ...