A field trial was conducted in the VII Region of Chile, where apple trees cv. 'White Winter' received a foliar spray in the fall, with urea alone or mixed with Parathion or with Parathion plus Citroliv oil. The effect of the treatments was evaluated in the following spring, by the method of Szkolnick (1969). Ascospores release of V. inaequalis was drastically suppressed by a single foliar application of 4% urea. However, a 34 fold increase in ascospores' liberation was observed, in September and October, in the treatment with urea plus Parathion and oil, compared to the treatments without oil. In November and December, this effect was minimal, and differences were not statistically significant (P = 0.05).