Biocontrol of Sclerotinia sclerotiorum in desert-grown winter lettuce using Coniothyrium minitans

• Published in: Phytopathology Vol. 95; no. 6
• Main Authors: Pryor, B, Chitrampalam, P, Matheron, M, Turini, T
• Format: Journal Article
• Language: English
• Published: 01.06.2005
• Subjects: Bacillus subtilis; Coniothyrium minitans; Sclerotinia sclerotiorum
• ISSN: 0031-949X

Trials were conducted in Yuma, AZ and Holtville, CA to evaluate the efficacy of Coniothyrium minitans in controlling lettuce drop, caused by Sclerotinia sclerotiorum, in desert production systems. Each trial was conducted in a split-split plot design with irrigation method (sprinkler vs. furrow) and inoculum density as primary and sub-plots, respectively. Sub-sub plots were either lettuce type (crisphead, leaf, Romaine) or treatment [Contans (a.i. = Coniothyrium minitans): 2.2 or 4.4 kg/ha, 1 or 2 applications; Rovral: 1.1 kg ai/ha, 1 or 2 applications; Companion (a.i. = Bacillus subtilis): 9.4 l/ha, 2 applications; or a combination of treatments]. Results revealed there was no significant effect of irrigation on disease incidence. Inoculum densities of 2 sclerotia/m bed did not result in significantly higher disease incidence, whereas densities of 10, 40, and 100 sclerotia/m bed resulted in significantly increasing incidence of disease. Leaf lettuce types were significantly more susceptible to S. sclerotiorum than were crisphead or Romaine. There were no significant differences between low and high application rates of Contans and no significant differences between 1 or 2 applications. In all trials, Contans was significantly more effective in controlling lettuce drop than Rovral or other biocontrol products.