Two species of planthopper infest rice. These are the brown planthopper (BPH), Nilaparvata lugens (Stal); and the whitebacked planthopper (WBPH), Sogatella furcifera (Horvath).
What it does
High population of planthoppers cause leaves to initially turn orange-yellow before becoming brown and dry and this is a condition called hopperburn that kills the plant.
BPH can also transmit Rice Ragged Stunt and Rice Grassy Stunt diseases. Neither disease can be cured.
Why and where it occurs
Planthoppers can be a problem in rainfed and in irrigated wetland environments. It also occurs in areas with continuous submerged conditions in the field, high shade, and humidity.
Closed canopy of the rice plants, densely seeded crops, excessive use of nitrogen, and early season insecticide spraying also favors insect development.
Check for the presence of insect:
Hopperburn is similar to the feeding damage or "bugburn" caused by the rice black bug. To confirm hopperburn caused by planthoppers, check for the presence of sooty molds at the base of the plant.
Why is it important
The feeding damage caused by planthoppers results in the yellowing of the plants. At high population density, hopperburn or complete drying of the plants is observed. At this level, crop loss may be 100%.
In field conditions, plants nearing maturity can have hopperburns if infested with about 400−500 BPH nymphs. In the 1970s and 1980s, BPH was considered a threat to rice production in Asia. BPH also transmit Rice Ragged Stunt and Rice Grassy Stunt viruses..
At a population density of 400−500 nymphs or 200 adults per plant, WBPH can cause complete loss of rice plants. Outbreaks of WBPH were reported in Pakistan in 1978, Malaysia in 1979, and India in 1982, 1984, and 1985.
How to manage
Outbreaks result from pesticides destroying natural enemies (BPH eggs hatch unchecked, and surviving BPH quickly build-up populations to damaging levels), or when longwinged planthoppers are being carried in by the wind.
To prevent outbreaks of planthopper:
To control planthoppers:
Mechanical & physical measures
Only apply insecticides to the seedbed, for BPH or WBPH, if all of these conditions are met:
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