The Combined Application of Trichoderma sp. and Bacillus sp. Powders to Control Dirty Panicle Disease Caused by Bipolaris oryzae in Rice

Abstract

Three isolate of Trichoderma spp. obtained from rice rhizosphere soil, Trichoderma sp. NS–01 and Trichoderma sp. NS–02, were classified as T. viride and Trichoderma sp. NS–03 as T. harzianum. Two isolates of Bacillus sp. NS–01 and Bacillus sp. NS–02 from rice leaves were classified as B. amyloliquefaciens and B. subtillis respectively. Testing the efficacy of antagonatic microorganisms to inhibit growth of Bipolaris oryzae NS–04 (from Krok Phra district, Nakhon Sawan province) found that Trichoderma sp. NS–03 and Bacillus sp. NS–02 could inhibit B. oryzae NS–04, did not statistically differ when compared to commercial strains of T. asperellum CB–Pin–01 and Bacillus sp. No2 respectively. In greenhouse condition, the use of antagonistic powders at concentration of 2 x 105 cfu/ml sprayed to control dirty panicle disease at 2 times. After spraying for 14 days, the results found that only Trichoderma sp. NS.–03 powder could reduce disease incidence at 55.84%, whereas the application of Trichoderma sp. NS.–03 powder combined with Bacillus sp. NS–02 provided the highest disease reduction at 72.98%, which was similar to Armure fungicide 30% w/v EC (Propiconazole + Difenoconazole) with 73.71% reduction. In addition, the combined use of Trichoderma sp. NS–03 and Bacillus sp. NS–02 powders at 15 gram of each powder per 20 litters water sprayed to control of dirty panicle disease in rice fields at 3 times for 21 days, it was found that the combined application of the antagonistic powders highly reduced the dirty panicle disease to 74.36% and provided the highest yield at 940.50 kg per rai. While the untreated control treatment had the highest disease and the lowest yield at 697.50 kg per rai, which was significantly different.