Disease incidence and yield loss due to foliar blight of wheat in Nepal
1998
Shrestha, K.K. | Timila, R.D. | Mahto, B.N. | Bimb, H.P. (Nepal Agricultural Research Council (NARC), (Nepal). Plant Pathology Division)
Helminthosporium leaf blight (HLB, tan spot) is a serious disease of wheat in Nepal, caused individually or in combination by Bipolaris sorokiniana (Sacc.) Shoem. and Pyrenophora tritici-repentis (Died.) Shoem. In recent years, the magnitude and severity of HLB have extended from the terai region (100 masl) to the hilly region (2400 masl). Since 1990, B. sorokiniana has been the predominant pathogen of the leaf blight syndrome. Incidence of seed infection was higher in samples from eastern terai than western terai and the hills. The relationship between seed infection and germination was significant and negatively correlated. Most of the improved and recommended wheat varieties are severely infected by the disease; however, varieties including NL 644, NL 623, BL 1413, Nepal 297, NL 625, NL 591, and Triveni showed moderate HLB resistance and BL 1420 was observed to be resistant. Eighty-six entries, resistant/tolerant to HLB, were selected from multilocation trials, and could be used as potential sources of resistance. Yield losses as high as 23.8 percent were recorded. Poor germination was experienced due to high B. sorokiniana infection levels in grain harvested during 1996. This problem was solved by treating the seed with Vitavax-200 before distribution to farmers. Disease management has been practiced in Nepal for the last few years. Incidence of HLB was significantly reduced by two irrigation cycles and three applications of propiconazole as a foliar spray at 0.5 L ha-1.
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