Rola mocznika w ograniczaniu infekcji pierwotnych jabłoni przez Venturia inaequalis (Cooke) Aderh. [Role of urea in the reduction of apple primary infections by Venturia inaequalis (Cooke) Aderh.]

Abstract

The effect of pre-leaf fall of 5% urea treatment on primary infection of apple by Venturia inaequalis, the cause of scab, was investigated in commercial apple orchards of McIntosh cv. in different regions of Poland, at Miłobądz, Sinołęka and Dąbrowice. Additionally, the development of pseudothecia and maturation of ascospores were evaluated in the spring on apple leaves of two cultivars (McIntosh and Gloster) treated with 5% solution of urea. Microscopic observations of leaves showed that urea treatment significantly reduced the number of pseudothecia (by ca. 90%) and ascospore production. Low number of ascospores after urea treatment has strongly affected primary infection of apple by the fungus in all tested orchards. Reduction of leaf infection on control trees was usually more than 30%. Also efficacy of chemical control of apple scab was significantly higher on plots treated with urea.