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1. Rice tungro viral disease occurred in an epidemic form in NE states during 1969 and 1970.This is one of the most damaging diseases. Tungro ischaracterized by stunting ofthe plant and leaf colours range from various shades of yellow to orange, the discolouration and rusty blotchesspreading downwards from the leaftip.
2. The young leaves may show a mottled appearance and slightly twisted whereas older leaves appear rusty coloured.
3. Tungro is the result of concurrent infection by two viruses -the single stranded RNA virus, rice tungro spherical virus (RTSV) and thedouble stranded DNA virus, rice tungro bacilliform band virus (RTBV) Both viruses are transmitted by several leafhopper species, more particularly Nephotettix virescens in semi-persistent manner.
4. The insect can become infective after feeding on diseased plants for 30 minutes and can transmit the virus almost immediately after feeding.
5. The females are more efficient in transmission than the males. Wild rice, rattoning stubble and grassy weeds may serve as source of virus between rice crop.
6. Use of resistant varieties controls the disease.