Tungro disease of rice
Causal
agent:-rice
tungro virus;syn. Rice leaf-yellowing virus.
Distribution:- The tungro disease has been
reported from Philippines, Thailand, western java, southern Sumatra and west
Bengal in India.
Symptoms
:- Generally,
the symptoms appear on leaves. The symptoms appear first on the emerging leaf
as a mild interveinal chlorosis followed by a mild mottling and then a
yellowing. Later on, stunting occur and symptoms become apparent on the lower
leaves which become yellow or yellow-orange, mottled, bent downwards from the
collar region and possess dark brown spots.
Transmission
of virus:- the
virus is transmitted by a leaf hopper Nephotettix impicticeps.
The leaf hopper retains infectivity for a short period only, and transmits the
virus immediately after feeding on an infected plant. The virus particle is
isometric and measure 30 to 3 mili-microne in diameter.
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