Rice
Asian Rice Gall Midge
Orseolia oryzae
Insect
In a Nutshell
- Tube-shaped structures at the base of tillers.
- Silvery leaf sheaths.
- Fails to produce panicles.
- Deformed, wilted and rolled leaves.
- Stunted growth.
- Small redish-brown, nightactive midge.
- Confusion with Yellow Stem Borer.
Can also be found in
Rice
Symptoms
Rice gall midge forms a tubular gall at the base of tillers, producing elongated silvery leaf sheaths called onion leaf or silver shoot (about 1 cm wide and 10−30 cm long). The affected tiller inhibits growth of leaves and fails to produce panicles. Plant stunting and leaf deformity, wilting and rolling are also symptoms caused by drought, potassium deficiency, salinity, and by rice thrips. To confirm cause of problem, check for presence of insects. Particularly, elongated-tubular eggs and maggot-like larva feeding inside developing buds.
Recommendations
Organic Control
Parasitization with platygasterid, eupelmid, and pteromalid wasps (parasitize the larvae), phytoseiid mites (feed on eggs), spiders (feed on adults) have successfully been used. Planting more flowering plant that attract the insects around the rice field also helps.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Use time insecticide applications accurately to control outbreak by spraying on emergence of rice gall brood. Products based on chlorpyriphos can be used against the Asian rice gall midge to control its population.
What caused it?
The Asian rice gall midge is found in irrigated or rainfed wetland rice environment during the tillering stage of the rice crop. It is also common in upland and deep-water rice. The insect remains dormant in the pupa stage but become active again when the buds start growing after the rains. The adult midge is night active and feeds insight the plant, therefore it is difficult to detect. Population density is favored by cloudy or rainy weather, cultivation of high-tillering varieties, intensive management practices. The damage is similar to that of Yellow Stem Borer.
Preventive Measures
- Use resistant varieties available locally.
- Plant early, at the beginning of the rainy season.
- Use a wider space between plants or a looser sowing rate.
- Plant trap plants that attract beneficial insects around the rice fields.
- Remove all off-season plant hosts around the rice field.
- Check the optimum recommendation of nitrogen and potash fertilizer.
- Use light traps along with sticky board with oil or glue to collect the moths.
- Plow plant debris of the previous crop immediately after harvest.
- Keep land fallow some weeks or months during off season.
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