Standardization of technique for artificial creation of false smut of rice and its management.

摘要

A methodology for the artificial induction of false smut of rice under field conditions was evaluated in Punjab, India, during 2006 and 2007. Rice (cv. PR-116) plants at the booting stage were inoculated with Ustilaginoidea virens using spore suspension. Four treatments, i.e. inoculation and maintenance of artificial humidity (MAH), inoculation without MAH, without inoculation but with MAH, and without inoculation and MAH, were evaluated. High humidity was maintained by spraying water in the field during daytime at one-hour intervals for 15 days. The efficacy of Kocide 3000 [copper hydroxide] (0.1 or 0.2%), Blitox 50 WP [copper oxychloride] (0.25%)/Tilt 25 EC [propiconazole] (0.1%), Score 25 EC [difenoconazole] (0.1%) and Contaf Plus 5 EC [hexaconazole] (0.2%) against the disease was evaluated. The fungicide was initially sprayed at the booting or heading stage; the second spray was given after 10 days. In 2005 and 2006, the disease incidence (DI) reached 80.65 and 86.85%, and the disease severity (DS) reached 3.24 and 4.80%, respectively, under inoculation + MAH. Under inoculation without MAH, DI values were 5.65 and 10.30, whereas DS values were 0.73 and 1.30%. Plants that were not inoculated but exposed to MAH recorded DI values of 2.67 and 4.56%, and DS values of 0.05 and 0.10%. Under no inoculation and MAH, DI values were 1.10 and 1.50%, and DS values were 0.12 and 0.20%. Blitox 50 WP sprayed at the booting stage followed by Tilt 25 EC sprayed after 10 days resulted in the lowest DI (4.00 and 0.00%) and DS (0.02 and 0.00%) values. The fungicides were most effective when initially given at the booting stage.