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(NAR) VOL. 6 NO. 1 / JANUARY - MARCH 1995

[ DA MEMORANDUM CIRCULAR NO. 3, June 30, 1994 ]


The incidence of Tungro virus has been observed in some provinces of Pangasinan, Cagayan, La Union, Laguna, Camarines Sur, Albay, Iloilo, Bohol, Cebu, Negros Oriental, Zamboanga Sur, Davao Norte, Davao Sur, and Davao Oriental. While the assessment that was conducted on the extent of infection is not a cause for alarm, the spread of the infection including its vector i.e. green leafhopper (GLH) may cause a significant decline in yield, if preventive and control measures are not undertaken as early as possible. As such, all concerned Government Agencies and its instrumentalities and non-government organizations are hereby tasked to observe the recommended preventive and control measures during their delivery of their respective services, to wit:

Preventive Measures

1. Avoid planting known susceptible varieties like IR-36, -42, -64, RC-12, -14, -16 and BPI-RI-10 in areas with known incidence of tungro.

Note: IR-64, RC-14 and BPI-RI 10 are susceptible in high pressure areas, therefore, distribution of these varieties should be guided by the incidence of tungro within a given area of a municipality.

2. Transplant early in wet season but not later than July 30, to avoid tungro infection during peak of green leafhopper (GLH) population and heavy inocolum pressure. For the dry season, transplant not later than January 30.

3. Three (3) croppings in a year should be discourages in areas with known tungro incidence.

4. Synchronize planting over large contiguous areas per locality within 45 days.

5. Adopt a fallow period of at least one month between season (e.g. May 15-June 15; November 15-December 15) for the community/locality, to avoid possible presence of inoculum for the next season/succeeding seasons.

6. The remaining stubbles in the areas must be plowed under before seedbeds with mosquito nets or any similar material.

Eradication Measures

1. Seedbeds with tungro infected seedlings must be destroyed.

2. If 25-50% of the plant population is infected with tungro within the 40 days after transplanting (DAT), immediately plow under. After plowing under, plant crops other than rice.

Note: If less than 25% infection after 40-50 days after transplanting (DAT) depending on the variety, the plants may still yield considerably, provided nitrogenous fertilizers shall be applied at recommended rate.

3. If less than 20% of plant population are infected from 60-100 days after transplanting (DAT), there is NO NEED TO SPRAY.

4. After complete harvesting, plow under or burn rice stubbles to prevent inoculum build-up.

For your guidance and strict compliance.

Adopted: 30 June 1994


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