Study on the fungicidal effects of WELGRO® Cu+Zn in controlling rice blast disease under field condition

Rice blast disease caused by Pyricularia oryzae Cavara is considered the most damaging disease of native rice cultivars in the north of Iran, so its chemical management has a special priority. In this study, the efficacy of 0.5, 1, and 2 kg/ha of WELGRO® (34.5% Copper and 37.3% Zinc) in controlling rice blast disease in comparison with 0.5 kg/ha of Tricyclazole (75% WP) were evaluated in field conditions in a randomized complete block design with four replications, in Astaneh-ye Ashrafiyeh and Rasht. For this purpose, Hashemi seedlings were transplanted at a distance of 20×20 cm in the 4×5 m plots. Treatments were applied at the first appearance of disease symptoms in the region for leaf blast and after heading for panicle blast. In the control treatments, water was sprayed. Leaf and panicle blast disease percentages were assessed seven days after the first spraying and one week before harvest, respectively. The results showed that the concentration of 2 kg/ha of WELGRO® compared to the control not only reduced leaf, node, neck, and panicle blast disease, 25.77, 24.22, 38.44, and 8.41% in Rasht and 58.70, 29.05, 43.11, and 43.15% in Astaneh-ye Ashrafiyeh, respectively, but also its efficacy in controlling blast disease and its yield and yield components was very close to that of Ticyclazole. It should be noted that the results of the present study were obtained in a situation where the severity of the blast disease in the experimental field was not in an outbreak state. If the disease is in epidemic conditions, not only the use of 2 kg/ha WELGRO®, but also the 0.5 kg/ha tricyclazole is not efficient for blast disease control. If a rice blast epidemic is not predicted, the use of WELGRO® in rotation with other fungicides can control the disease, delay fungicide resistance, and also it can be used in organic rice production.