Preventive and Therapeutic Effects of New Fungicides on Rice Blast

[Objectives] The paper was to identify the characteristics and the potency of new fungicides to rice blast disease, and study their preventive and therapeutic effects on the disease. [Methods] Six new and conventional fungicides with different mechanisms of action were selected to compare their preventive and therapeutic effects on rice seedling blast in greenhouse. [Results] The agents which showed to be highly efficacious in blast prevention (greater than 90%) were 25% pyraclostrobin EC, 20% fenoxanil SC, 75% tricyclazole WP and 50% prochloraz-manganese WP sprayed at the dosages of 112.5-150, 180-360, 270-450 and 450-600 g/ha, respectively. The therapeutic effect of new fungicides 25% pyraclostrobin EC and 50% prochloraz-manganese WP on rice blast were above 90% when the dosages were 90-150 and 360-600 g/ha, respectively. The therapeutic effect of the conventional fungicide 40% isoprothiolane EC on rice blast was 69.04% when the dosage was 480 g/ha, while those of other fungicides were worse. [Conclusions] Both 25% pyraclostrobin EC and 50% prochloraz-manganese WP have good preventive and therapeutic effects on rice blast, which will provide a reference for the use of these fungicides in the field.