Apple scab control with 1 to 6 sprays of fungicide applied on a 10-day schedule

Andrea Torres P1. y Orlando Andrade V.1

A research on scab (Venturia inaequalis (Cke.) Wint.) control was conduced at Carillanca Exp. Sta., Vilcún,IX Region of Chile, in apples cv. Red King Oregon, Granny Smith Spur, Golden Spur and Top Red, during the 1991/92, 1992/93, and 1993/1994 growing seasons. One to six applications ofthe fungicide flusilazol was sprayed on a 10-day schedule. A check without fungicide was included. The purpose was to determine the minimum number of sprays required to obtain an acceptable level of scab control to meet fruit production requirements of this area. A differential response of the apple cultivars to the treatments was observed, because of their disparity to scab susceptibility. Disease rates recorded on the checks without fungicide during the three growing seasons ranged from 77% to 100% on fruits, and 31 %to 100% on leaves. During 1992/1993, the nontreated checks resulted with 100% of their leaves and fruits dropped due to scab. Treatments with 4, 5, and 6 sprays significantly reduced the level of diseased leaves and fruits, and increased the number of healthy fruits and fruit weight. Less than 4 sprays resulted in an unsatisfactory level of scab control.

Keywords: scab, venturia, apple, control.
1 Centro Regional de Investigación Carillanca (INIA). Casilla 58-O, Temuco. Chile.