Control of apple scab based on the system of Mills

Abstract

To test new technology in controlling apple scab caused by Venturia inaequalis (Cooke) Winter, and to reduce the number of treatments, an experiment was carried out at the research station of Caçador, SC, Brazil in the growing season of 1982/83. Four-year old plants of the varieties Fuji and Gala were used. Fungicides were applied on randomized blocks using six replicates with two plants of Fuji and one of Gala each unit for the following treatments: 1. treatment based on Mill’s system; 2. conventional treatment with sprays every 6 to 10 days; 3. control unit with pest management only. Seventy infection periods with 15 low, 8 medium, and 47 heavy infections were registered. To control apple scab 18 fungicide sprays were necessary using the conventional disease management and 17 using Mill's system. The ascospore flight of Venturia inaequalis began the end of September ceasing the end of November 1982. Considerable differences between the treated and untreated blocks of Fuji and Gala could be observed, concerning the attack of apple scab (Venturia inaequalis), bitter rot (GIomerella cingulata), apple blotch disease (Gloeodes pomigena) and fly speck (Leptothyrium pomi), total weight/plant, weight/fruit, fruit size and yield per hectare.