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Source: NewsBeezer [abridged, edited]

Approximately 1000 acres [about 405 ha] of rice fields in Albay [Bicol region] are unproductive due to [tungro] virus disease. MP Joey Sarte Salceda said the disease has so far affected various urban farmers. "It should be controlled as soon as possible during the reproductive phase," he said.

Rice [tungro] disease is caused by the combination of 2 viruses that are transmitted by leafhoppers. Salceda said he had already asked the Department of Agriculture to do something to prevent the infestation. "As chairman of Ways and Means, I will help secure funding to keep Albay rice granaries free from infestation."

To stop the spread of the disease, the prosecutor in Bicol [region] initially supplied farmers with insecticide to be sprayed into the affected areas, which could cover 80 hectares. [The] Agriculture Minister has assured that the agency will undertake interventions against the infestation.

Communicated by:

[Tungro is one of the most damaging rice diseases in South East Asia and is spreading in the region. Yield losses of up to 100 percent have been reported. The disease is due to a co-infection involving 2 unrelated viruses: _Rice tungro bacilliform virus_ (RTBV; only species in genus _Tungrovirus_, family Caulimoviridae; ds DNA genome) and _Rice tungro spherical virus_ (RTSV; genus _Waikavirus_, family Secoviridae; ss RNA genome). More than one genotype of each virus may exist in the same plant.

Symptoms include leaf discolouration, stunting, reduced tillering, and reduced grain production. All growth stages of rice are susceptible, but losses are higher for infections early in the growth cycle. Tungro is transmitted by leafhoppers, the most efficient vector being the green leafhopper _Nephotettix virescens_. RTBV enhances the symptoms of RTSV and cannot be transmitted unless RTSV is present as a helper virus. A number of grassy weeds and volunteer rice plants can serve as virus reservoirs. Infectious vector insects can spread the viruses over long distances. The disease is not seed transmitted.

Disease management may include vector control, cultural practices, and use of rice varieties resistant to the vectors and/or the viruses. However, vector adaptation on leafhopper resistant crop varieties has been a problem. The presence of multiple viral genotypes in a single location (suggesting an unstable virus population) poses a further challenge to achieving durable crop resistance.

Philippines: (with provinces) and
Location of Albay:

Tungro symptoms on rice:, and
Tungro-affected rice fields:,,, and (compared with resistant cultivars)
Tungro vector green leafhopper:,, and (larvae)
RTBV & RTSV particles, electron micrograph:

Information on rice tungro disease:,,,,, and
Virus taxonomy via:
Green leafhopper information and taxonomy:,, and
- Mod.DHA]


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