Efficacy of Fungicides to Control Rice Seedling Rot Disease and Effects on Antagonistic Microorganisms

Abstract

Rice cultivation with a seedling transplanting machine is often destroyed by pathogenic fungi such as Curvularia lunata, Bipolaris oryzae and Fusarium spp. Rice seedlings are infected with fungi, resulting in abnormal seedlings that are not suitable for transplanting. This research aimed to test the effective fungicides registered by the Department of Agriculture to control rice seedling rot disease, for proper application and to investigate the effects of fungicides on antagonistic microorganisms. In 2022, fungicide efficacy tests were conducted at the Chai Nat Rice Research Center under greenhouse and rice seedling nursery conditions. The results found that seeds were soaked, coated by fungicides for 12 hours, sprayed fungicides on the seeds with fenbuconazole 24% W/V SC 8- 40 ml per 20 liters of water and hexaconazole 5% W/V SC 4- 20 ml per 20 liters of water could reduce the disease incidence 71.55-83.88%. Both fungicides could be used as alternative fungicides to replace carbendazim 50% WP for further recommendation to farmers. Study effects of fungicides on antagonistic microorganisms on PDA and NA, the results showed that fenbuconazole 24% W/V SC, hexaconazole 5% W/V SC, carbendazim 50% SC and metalaxyl 35% DS effects on mycelial growth of Beauveria bassiana, Metarhizium anisopliae and Trichoderma harzianum. Metalaxyl 35% DS also affects the sporulation of T. harzianum. All fungicides did not affect the growth of Bacillus amyloliquefaciens.