Rice ragged stunt
Causal agent: Ragged stunt virus
The brown plant hopper transmits the disease. The early in star nymphs of the insect are more efficient in transmitting the disease than older ones. Five-day-old nymphs are the most efficient transmitters. The virus is acquired within a feeding period of 24 hours.
Viral particles are 63-65 nm in diameter and consist of five proteins. They are mostly found in phloem and gall cells. The genome consists of ten double-stranded RNA segments.
The virus is circulative and propagative in the insect vectors.
Symptoms:
- Infected plants severely stunted during early growth stages of the crop
- Leaves short and dark green with serrated edges
- Leaf blades twisted at the apex or base, which result in the spiral shape of the leaves
- Leaf edges uneven and the twisting give the leaves a ragged appearance
- Ragged portions of the leaves are yellow to yellow-brown
- Vein swellings develop on the leaf blades and sheaths
- Swellings pale yellow or white to dark brown
- Flag leaves twisted, malformed, and shortened at booting stage
- Flowering is delayed
- Incomplete panicle emergence
- Nodal branches produced at upper nodes
- Partially exerted panicles and unfilled grains
Management practices:
- There are no specific control measures for the ragged virus disease except for the use of resistant varieties.
- Because some rice varieties are resistant to the brown plant hopper, to the virus, and to both.
- Cultivars resistant to the vector have low disease incidence.
- The application of insecticides to migratory plant hoppers is being used in temperate countries to reduce disease incidence.
- Login to post comments
- 2315 reads