Spore release dynamics of Ustilaginoidea virens(Cooke) Takahashi in the air and its influence factors at rice growth period

ObjectiveThis experiment studied the spore release dynamics of Ustilaginoidea virens(Cooke)Taka-hashi in field and its influence factors in order to provide scientific reference for predicting occurrence of rice false smut.MethodThe spore release of U. virens using the spore trap in Sichuan rice growing area were monitored,and spore release dynamics of U. virens in field were analyzed. Meteorological data during 2014-2016 at rice growth period were collected,including temperature and average humidity,to study the inner relation among meteorological factor,spore release and rice false smut.ResultIt was found that the spores release exhibited dynamic change during rice growth period. Meanwhile,the results showed that the spores release rose gradually from middle May to early July,spore release boosted sharply in late July and reached the peak in late July and early August,then declined gradually from middle August. In late September,spore amount declined to the level in May. Symptom of rice false smut was visible after 10 d from the spore release peak. The spores release was positively correlated with the pathogen quantity in field and disease severity in the last year,and it also related to temperature and humidity. Conditions with average temperature being 25 to 30℃and relative humidity over 85%were advantageous to the spores release and the happening of rice false smut.ConclusionThere is close connection among spore release,meteorological factors and rice false smut.