Barrier crops reduce disease level

CHILLI IS grown both as a vegetable and a spice crop. Out of the 22 viruses infecting chilli, mosaic and leaf curl disease are the most devastating.Mosaic disease is transmitted by mechanical means and by insect vectors such as aphids.

Leaf curl infestation

Leaf curl disease is transmitted by white flies (Bemisia tabaci). The incidence of mosaic becomes severe when the vector population increases in the field. Natural conditions such as temperature of 25-35 degrees C favour high vector population.

Disease characteristics

The disease is characterised by puckering of leaf blade, and gradual reduction in the size. Diseased plants flower poorly with low fruit set.In case of leaf curl the disease is characterised by curling of the leaves, and thickening and swelling of veins. In advanced stages the whole plant appears bushy, with stunted growth and fewer flowers. Both the infestations should be managed from seedling stage itself by using seeds from virus free plants. The nursery beds should be covered with nylon net or straw to protect the seedlings from viral infections. Spraying metasystox or rogar at 1ml per litre of water at 10 days' interval will control the incidence in the nursery. In the main field, infected plants should be removed as soon as they are noticed. - Raising barrier crops such as maize, sorghum, pearl millet or snap bean around chillies in two to three rows will reduce the disease level. - Application of Diazinon, Metasystox, Melathion or Endosulphan 0.2 per cent at 15 days' interval till the harvest.- Spraying monocrotophos at 0.05 per cent at 10 days interval in the field. Spraying should be stopped 15-20 days before harvest of the crop.MALLIKARJUN Y.KENGANAL
HEMAVATI RANEBENNUR
& A.S. BYADGI

Department of Plant Pathology, Dharwad UAS, Karnataka