Control of Rhizoctonia root rot of bell pepper in greenhouse using chemicals and biological fungicides

Bell pepper with the scientific name Capsicum annuum L. belongs to the Solanaceae family. Among the major pepper diseases, root rot caused by the fungus Rhizoctonia solani has the economic importance. The common method to control this disease is to use the chemical fungicides. In order to control Rhizoctonia root rot disease of bell pepper, a number of commercial biological agents based on Trichoderma harzianum, Glomus sp. mycorrhizal fungus, Bacillus sp. and Pseudomonas sp. bacteria and three chemical fungicides Tebuconazole, Copper oxychloride and Mancozeb were investigated in greenhouse conditions. The analysis of variance showed that the treatments had significant difference (P≤ 0.01) in all the examined traits. The mean comparisons of the treatments were evaluated based on disease inhibition traits including the length of the necrotic tissue with the largest wound and the disease index and plant growth promotion traits, including plant fresh weight, plant height, root dry weight and shoot dry weight. The treatments of negative control (no pathogen) and fungicide tebuconazole had the greatest effect on most of the traits, and the treatments of Potabarvar and Mycoroot and positive control (with pathogen) had the least effect. Among the biological control treatments, based on the lowest disease index and the lowest wound length, the combination of biological agents, Parsbacil, Probio96, Alkagreen, Trichoran-P and Tricho were ranked respectively. In the study of agricultural traits, biological treatments, combination of biological agents, Parsbacil and Probio-96 showed the highest values. In the management of this disease, apart from the chemical control method (Tebuconazole), the best option with a relatively similar statistical level was Parsbacill combination (SC) containing Bacillus velezensis strain M11-RTS, and Probio-96 containing Bacillus subtilis bacteria (P≤ 0.01).