e course



10. Root-lesion Nematodes: Pratylenchus spp. (Tylenchoidea: Tylenchidae)


Distribution and status: World wide. Of the various ornamental plants, roses are the most affected by parasitic nematodes. These root-lesion nematodes are vagrant parasites of plant roots. Occasionally become serious and warrant control measure.
Damage symptoms : Lesion nematodes feed on the parenchyma of the root and cause lesions, specially when a large number of them feed together. The root injury results in decreased growth of the aboveground portions. The plants bear small or no flowers at all. They inhabit the aboveground portions only in rare cases.
Bionomics : Both adults and larvae move in and out of the roots. The penetration usually occurs in the mature region of the rootlets and not from the root-tips. A female usually lays one egg per day. The egg stage lasts 16-20 days. The development and reproduction are rather slow in P. pratensis taking 54 days to complete the life-cycle. In other species, like P. zeae, the life cycIe is completed in 35-40 days. During periods of drought, these nematodes lie quiescent, but they resume growth as soon as free moisture is available. The population of the root-lesion nematodes is high in October
Management : Cultivate  French marigold or American marigold or sesame in rotation or as an intercrop
Mix phorate 1O G @ 10 kg/ha or carbofuran 3G @ 30 kg/ha in soil at the time of planting.