Grassy stunt virus

For study

1. Grassy stunt virus

2. Generally rice grassy stunt virus occurrence is not widespread. The disease can become a serious problem of limited rice growing areas when there are brown planthopper outbreaks. Rice grassy stunt virus affects rice crops in areas where continuous, year-round rice growing is practiced. The virus is transmitted between plants by insect vectors. Nymph and adult stage plant hoppers are common vectors for rice grassy stunt virus. The plant hoppers need to feed on an infected plant for at least 30 minutes to pick-up the virus. Grassy stunt virus (RGSV) is a member of the Tenuivirus group.

3. Symptoms Diseased hills are severely stunted with excessive tillering and a very upright growth habit Diseased hills has a grassy and rosette appearance Leaves short, narrow, and yellowish green with numerous small rusty spots or patches, which form blotches Retention of green coloration of the leaves after application of sufficient nitrogenous fertilizers Infected plants usually survive until maturity, but produce no panicles The symptom develops 10-20 days after infection.

4. severely stunted plants excessive tillering very upright plant growth grassy and rosette appearance of plants yellowish green leaves that are shorter and narrower than normal leaves that remain yellow even after application of sufficient nitrogen fertilizers numerous small rusty spots or patches on leaves, which merge into blotches leaves have a mottled appearance plants that fail to produce panicles

5. Identification of pathogen The virus exists in the vector and in the rice crop. Brown planthopper nymphs and adults transmit it where rice is grown year-round. The macropterous forms or the long winged adults of the insect are important in spreading the disease than the short winged forms They feed on the diseased plant for at least 30 minutes to pick-up the virus. Higher infection is attained after prolonged inoculation feeding periods of up to 24 hours. The availability of the vector encourages the damage. Rice grassy stunt virus (RGSV) is a member of the Tenuiviruses.

6. At a population density of 400−500 nymphs or 200 adults per plant. crescent-shaped white eggs inserted into the midrib or leaf sheath white to brown nymphs brown or white adults feeding near the base of tillers

7. Management Strategies Avoid close planting and provide 30 cm rogue spacing at every 2.5 to 3.0 m to reduce the pest incidence. There are varieties released by IRRI, which contain genes for BPH resistance, like IR26, IR64, IR36, IR56, and IR72.

8. This can be done either through the use of insecticides, brown plant hopper-resistant varieties, or synchronized crop establishment. Infected stubble needs to be plowed under after harvest to reduce the virus source.

9. plouging and harrowing the field to destroy stubbles right after harvest in order to eradicate other hosts.