Journal of Pure and Applied MicrobiologyVol. 3 No. 2

Evaluation of Commercially Available PGPR for Control of Rice Sheath Blight Caused by Rhizoctonia solani

K. Vijay Krishna Kumar, et al.,

1Department of Entomology & Plant Pathology, Auburn University, USA, 2Department of Plant Pathology, Andhra Pradesh Rice Research Institute, Maruteru, India, 3Rice Research Station, LSU AgCenter, LA, USA, 4Department of Biological Sciences, Auburn University, USA. 5Department of Microbiology, College of Life Sciences, Shandong Agricultural University, Taian, Shandong Province, China.

Received on 03 July 2009 and accepted on 15 August 2009



Sheath blight disease of rice caused by Rhizoctonia solani is a major production constraint in all rice producing areas of the world. The annual losses due to sheath blight are estimated to be 25 % under optimum conditions of disease development. Disease management is currently focused on extensive use of fungicides which has created concerns about environmental pollution, pathogen resistance and escalating costs. Field trials were conducted during rainy seasons of 2005 and 2006 in randomized block design with three replications to assess the commercially available bio-pesticide products for their effect on sheath blight. Products evaluated were Achook (Azadirachtin), Biotos (Plant activator), Tricure (Azadirachtin), Ecomonas (Pseudomonas fluorescens) and Bavistin (Carbendazim) in 2005 and Biofer (Plant extract), Biotos, Defender (Plant extract), Ecomonas, Florezen P (P. fluorescens), Trichozen (Trichoderma viride) and Bavistin in 2006. Products were applied three times as foliar sprays after appearance of first symptoms initially and repeated at 10 days interval. The disease severity was measured by adopting Highest Relative Lesion Height (HRLH) at 90 days after transplanting. The chemical (Bavistin) reduce disease severity 52% and 50% compared to the control. Corresponding reductions in disease severity with the bio-pesticides ranged from 22% to 48% in 2005 and from 15% to 31% in 2006. Specifically with PGPR, the disease reductions ranged from 14% to 38% compared to the control in both the years. Grain yields were assessed at 120 days after transplanting and significantly increased grain yields (3,901 and 1,938 kg/ha) over control (2,690 and 1,550 kg/ha) were obtained with PGPR in 2005 and 2006 respectively. Our results showed that there is a scope for effective management of sheath blight disease with the use of the currently available PGPR and other products that are available under the conditions evaluated.

Keywords : Rice, Sheath blight, Rhizoctonia solani, PGPR.