Viruses: have we exaggerated their significance?. Working Paper No. 90-6
1990
Mariano, J.S. | Demonteverde, V.E. | Perez, J. | Vander Zaag, P. (Philippines. Bureau of Plant Industry, Baguio City)
To determine future international and national support to seed production programs, survey of 99 farmers in the highlands of the Philippines was accomplished during 1990. Leaf samples were collected randomly from representative fields in the major potato growing area. These samples were analyzed for viruses using ELISA [Enzyme-Linked Immunosorbent Assay]. Tuber yield data was obtained at harvest. Farmers were interviewed about the history of their seed (source and the number of generation they had grown it). Twenty-five percent of the fields sampled were completely free of PVX, PVS, PVY and PLRV. Only 2% had PVY and 17% had PLRV infection. PVX and PVS were encountered in 41 and 45% of the fields sampled. Virus infection had absolutely no influence on tuber yields which averaged about 25 t/ha. There was no relationship between seed generation (the number of times the farmers had multiplied the seed) and the tuber yield. There was also no relationship between elevation of the field and virus infection level or between virus level and yield. well developed seed flows have been developed from certain higher elevation areas to neighboring areas. Results suggest that aphids are not a serious pest, that the popular variety Granola does have a certain level of field resistance to all viruses but especially to PVY and PLRV and by not cutting the seed farmers have kept PVX and PVS under control. This indigenous seed system can be best supported by continuously providing small quantities of completely virus free planting materials to selected farmers in the prime seed producing areas.
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