Determination of efficacy of some biopreparations against cotton seedling diseases

This study has been undertaken to determine pathogens causing damping off in major cotton growing areas of Aegean Region of Turkey and to investigate control possibilities by using biological and chemical preparations during 2006-2007. According to the survey results, 80.95% of 46 diseased cotton seedling samples collected in 2007 and 84.61% of 26 collected in 2006 was infested with Rhizoctonia solani. The cotton (cv Carmen) seed treatment of two endophytic bacteria Burkholderia cepacia (C5) and Bacillius megaterium (F5), one fungal biocontrol agent (Trichoderma harzianum KUEN-1565) and three fungicides Trilex (triadimenol %30 + metalaxyl % 28.35 + trifloxistrobin %22), BYF 182 (pyflufen 500 g/l), Vitavax 200 FF (carboxin 205 g/l + thiram 205g/l) were evaluated in both pot and field trials conducted in two locations (Söke and Nazilli) in 2007 against damping-off caused by R. solani. The treatment of pyflufen (6.25%), Trilex (12.5%), Vitavax (13.3%) and F5 (19.4%) caused significant pre-emergence damping-off losses in pot trials with artificial inoculation while pyflufen (65,63%), Trilex (61.9%) and Vitavax (59.4%) significantly increased cotton stand. In Söke field trials, the seed treatment of Vitavax and pyflufen resulted in 15.8% and 18,5% pre-emergence damping-off, respectively, but only pyflufen seed treatment caused significant increase (66.4%) in cotton stand. In Nazilli field trial, Vitavax and Trilex seed treatment resulted in the lowest incidence of pre-emergence damping-off (28.5% and 41.1% respectively) and caused significant increase in cotton stand (56.2% and 45.8%, respectively). The highest seed-cotton yield (421.8 kg/da) was recorded with pyflufen in Söke field trials.Key wordsDamping-off, Rhizoctonia solani, Burcholderia cepacia, pyflufen, biological control