Temporal dynamics of fresh corn rust in Guangzhou

A field investigation was conducted to monitor occurrence dynamics of fresh corn rust,with sampling method of five-spot from August to December,2012. In addition,the relationship between corn rust and corn growth period was also analyzed. The results showed that occurrence of rust increased with corn growing. The disease appeared from middle of September( seedling stage of fresh corn),and reached up to 90% in December. Fresh corn was sensitive to rust at flowering stages,at which damage of the disease increased rapidly,and both disease incidence and severity were significantly higher than that at seedling or jointing stages. Our study also indicated that rust made serious damage on fresh corn of autumn planting. Therefore,control measurement to the disease should be advanced,especially at corn flowering period.