Control of Rice Blight on Dry Nursery Seedling by Fungicide and Physiological Regulation on Rice Seedling

In order to select active fungicide for control rice seedling blight, the effects of several protective fungicides, such as mancozeb and thiram, and some systemic fungicides, such as isoprothiolane, hymexazol etc. were evaluated by nursery dish test. Lab toxicity test on two pathogens caused rice seedling blight of Rhizoctonia solani and Fusarium spp. in vitro and test of effect of fungicides on rice seedling growth were also conducted. The results showed that isoprothiolane, hymexazol and thiophanate-methyl, which had lower toxicity to the pathogens but stimulated seedling growth and improved resistance to low temperature stress of seedling, had good effects on control rice blight of dry nursery seedling, their protected effects varied from 65% to 81%. On the contrary the triazole fungicides such as triadimefon, propiconazole and diniconazole, which had higher toxicity to the pathogens but inhibited seedling growth, had lower control effects, their protected effects varied from 51% to 75%. Thus isoprothiolane is a better fungicide for control of rice seedling blight. It can be used single or mixed with other fungicides. For the control of the happening of rice seedling blight disease, caused by several pathogens and influenced by low temperature and alkaline of soil, it is suggested that the in vivo test first, then the in vitro test should be used for the screening of the active compounds and combination of fungicides of (different) active range is necessary in control practice.