ChileanJAR

During the 1979 and 1980 seasons, two experiments were performed at the Curico Province, on Red Del icious and Red King Oregon apple trees, in order to evaluate the effect of urea applied at a 2 per cent rate, prior to leaf fall, in the reduction of the spring primary inoculum of apple scab. In 1979, the trial was done at Los Niches, and the trees treated with urea received three applications. In 1980, the experiment was carried out at Teno, and the urea treatments consisted of two and one spray during the season. In both experiments, untreated trees were left as checks. Eight days after the Iast application, scab infected leaves were collected from each treatment and placed under wooden frames covered with a wire screen. Results were quantified by measuring the ascospore discharge, using the methodology described by Szkolnick. At Los Niches, the three urea sprays reduced 94.1 per cent the primary inoculum, compared to the untreated check. At Teno, two applications of urea reduced the inoculum 66.7 per cent, and three sprays, 94.2 per cent.