PhilRice warns farmers vs. rice plant viruses
Published May 11, 2020 12:00 am
By Ellalyn De Vera-Ruiz
Farmers should watch out for certain types of viruses that may infect rice plants, as there is no known treatment as yet to some of these viruses, according to an expert of the Philippine Rice Research Institute (PhilRice).
(PIXABAY / MANILA BULLETIN)
Plant pathologist Jennifer Niones of the Department of Agriculture's PhilRice cited four types of viruses --- namely, tungro, dwarf, grassy stunt, and ragged stunt --- which farmers must guard against to minimize significant yield losses.
Tungro virus is an extremely damaging rice disease occurring in South and Southeast Asia that leads to 70-100 percent yield loss. Rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) cause this disease, Niones said.
As infected plants cannot be treated, farmers must consider preventive measures especially if their area had past incidences of tungro infestation, she said.
Dwarf virus, which was first observed in the rice fields of Midsayap, Cotabato, could reduce yield by 50 to 80 percent, especially when it strikes down at vegetative stage. Infected plants show pronounced stunting, increased tillering, and shortened darker green leaves with fine chlorotic specks, Niones said.
She noted that the spread of dwarf virus could be prevented through plowing of the fallowed rice field and synchronous planting.
She added that applying insecticide to rice seedlings before transplanting could also be an option, while areas infected during the previous cropping season should be immediately plowed.
The grassy stunt virus could cause stunting and yellowing of the plant. This virus is commonly spread by nymph and adult brown plant hopper.
This virus, Niones said, frequently affect fields where year-round and continuous rice growing is practiced. Although plants can be infected in all growth stages, infection usually happens during the tillering stage, she said.
Niones pointed out that the virus can be managed through planting brown plant hopper-resistant rice varieties.
The populations of brown plant hopper should also be immediately managed, while infected fields should be plowed right after harvest to reduce the virus source, she added.
Another virus also transmitted by the brown plant hopper, Niones said, is the rice ragged stunt virus, which can bring up to 80 percent yield losses. It could cause severe stunting during early crop stages, green leaves with darker than the normal color that appears to have jagged uneven edges, and appearance of yellow to yellow-brown leaves that twist into spiral shapes at the base of leaf blades.
Like the tungro virus, ragged stunt virus-infected plants cannot be treated so preventive rather than direct-control measures should be implemented, she added.
Niones noted that to manage the four types of viruses, infected plants should be immediately removed once the disease is detected.
"They can be prevented by practicing a fallow period of at least one month between each crop to reduce the pests’ food supply; reducing their populations. Resistant varieties should also be considered but insecticide should only be applied when needed," she said.
(PIXABAY / MANILA BULLETIN)
Plant pathologist Jennifer Niones of the Department of Agriculture's PhilRice cited four types of viruses --- namely, tungro, dwarf, grassy stunt, and ragged stunt --- which farmers must guard against to minimize significant yield losses.
Tungro virus is an extremely damaging rice disease occurring in South and Southeast Asia that leads to 70-100 percent yield loss. Rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) cause this disease, Niones said.
As infected plants cannot be treated, farmers must consider preventive measures especially if their area had past incidences of tungro infestation, she said.
Dwarf virus, which was first observed in the rice fields of Midsayap, Cotabato, could reduce yield by 50 to 80 percent, especially when it strikes down at vegetative stage. Infected plants show pronounced stunting, increased tillering, and shortened darker green leaves with fine chlorotic specks, Niones said.
She noted that the spread of dwarf virus could be prevented through plowing of the fallowed rice field and synchronous planting.
She added that applying insecticide to rice seedlings before transplanting could also be an option, while areas infected during the previous cropping season should be immediately plowed.
The grassy stunt virus could cause stunting and yellowing of the plant. This virus is commonly spread by nymph and adult brown plant hopper.
This virus, Niones said, frequently affect fields where year-round and continuous rice growing is practiced. Although plants can be infected in all growth stages, infection usually happens during the tillering stage, she said.
Niones pointed out that the virus can be managed through planting brown plant hopper-resistant rice varieties.
The populations of brown plant hopper should also be immediately managed, while infected fields should be plowed right after harvest to reduce the virus source, she added.
Another virus also transmitted by the brown plant hopper, Niones said, is the rice ragged stunt virus, which can bring up to 80 percent yield losses. It could cause severe stunting during early crop stages, green leaves with darker than the normal color that appears to have jagged uneven edges, and appearance of yellow to yellow-brown leaves that twist into spiral shapes at the base of leaf blades.
Like the tungro virus, ragged stunt virus-infected plants cannot be treated so preventive rather than direct-control measures should be implemented, she added.
Niones noted that to manage the four types of viruses, infected plants should be immediately removed once the disease is detected.
"They can be prevented by practicing a fallow period of at least one month between each crop to reduce the pests’ food supply; reducing their populations. Resistant varieties should also be considered but insecticide should only be applied when needed," she said.