Evaluation of three control methods of white mold (Sclerotinia sclerotiorum (Lib.) de Bary) in lettuce (Lactuca sativa L.)

摘要

In the lettuce crop (Lactuca sativa L.), the main restrictive phytosanitary factor is a disease known as White mold caused by the fungus Sclerotinia sclerotiorum (Lib.) of Bary. In order to contribute to the knowledge of this disease for its management in the field, a trial was conducted between February and May 2006. Three control methods were compared: application of 0.5 kg· ha^-1 procimidone, 0.25 g· m^-2 soil of conidiospores of Trichoderma harzianum (DSM 14944), solarization, solarization integration with procimidone and solarization with T. harzianum. Sclerotinia incidence, inoculum density in soil before and after the trial, the soil temperature during solarization, and productivity were evaluated. The average inoculum density was 1.67 and 2.07 sclerotia for 100 g soil before and after the trial, respectively. The soil solarized temperature was increased up to 50°C with an average of 34.69 °C toward the midday. The incidence percentage of the disease was: procimidone 3.3%; T. harzianum, 10,0%; solarization 15.8%; solarization with procimidone, 8,8%; solarization with T. harzianum, 9.2% and check 18.3%. Significant differences were not founded for the productivity. In conclusion, the disease control was the best one when performed with procimidone application and the deficient when done with T. harzianum and solarization.