Status of False Smut (Fs) of Rice in Eastern Uttar Pradesh, India

Abstract

FS (false smut) caused by Claviceps oryzae-sativa Hashioka [Ustilaginoidea virens (CKe) Tak.] has become a very important disease of wet season rice in eastern Uttar Pradesh. Meteorological factors relationships to FS incidence indicate that relatively lower temperatures (around 20 C) and high humidity (above 90%), coupled with well-distributed moderate rainfall during flowering, favored the disease. Late sowing usually resulted in higher FS infection. The disease was more severe at higher fertility levels (100-50-50 kg NPK/ha) than at lower fertility levels (50-25-25 kg NPK/ha). The percentage of smutted grains/panicle varied considerably in different varieties, but there was little variation in the size of smut balls. There appears to be a direct correlation between percentage of infected tillers and percentage of smutted grains/panicle. FS infection reduces grains/panicle and 1,000-grain weight, compounding yield reductions. It increases the number of partially filled and unfil1060led grains leading to high chaffiness. The seeds near smutted grains have lower germination than seeds from healthy panicle. Eastern Uttar Pradesh had a FS epidemic 1984-1985 to 1985-86. FS incidents ranged from 10 to 30% in affected rice plots. Newer cropping technology, including planting high N-responsive varieties, enhancing the moisture supply, and including late sown wheat in the crop rotation, aggravated the disease in farmer's fields. In years of severe incidence, FS losses equaled losses to bacterial blight and sheath