Biological Control of Cotton Seedling Diseases by Fluorescent Pseudomonas spp.

Seedling root rot seen in many plants including cotton is an important disease that leads to large economic losses. Human health and the environment are negatively affected as a result of using fungicides for disease control. The goal of this study was to determine the effects of fluorescent Pseudomonas (FP) bacteria against seedling root rot pathogens both in vitro and in vivo conditions. 59 FP isolates obtained from the rhizosphere of cotton and weeds on the field were tested by dual-culture assays in vitro. After applying effective FP isolates on the seeds, antagonistic effects against the seedling root rot pathogens were investigated in a climate chamber. Resulting of dual-culture tests, FP40 had maximum effect (49.60%) against Rhizoctonia solani. Besides, FP51, FP48 and FP35 had highest impact as 43.80%, 43.50%, and 43.10% against Fusarium sp., respectively. Pythium deliense was mostly effected by FP57 (59.80%), FP52 (57.80%) and FP56 (57.60%). While isolates FP35 and FP57 provided protection over 70% against all three pathogens in a climate chamber, they were as effective as commercial fungicides (Vitavax and Maxim) and biofungicide (Subtilex) and shown promising results.