The results of six trials carried on Richard Delicious apple trees and one on Granny Smith, at Los Niches, Curicó Province, Chile, testing different fungicides, applied following two systems, for the control of apple scab, Venturia inaequalis (Cke.) Wint., are reported. Four trials followed a fixed calendar system, based on the residual effect of the fungicides tested, and in the other three, the treatments were applied only when the climatic conditions were favorable for the fungus infection. These conditions were detected comparing the lectures from a thermograph and a surface wetness recorder, installed in the orchard, with the Milis Tables.
The effects of the different treatments are given, indicating their side effect on fruit russet, when this was aboye normal. The following chemicals (doses expressed in 9 or cc/100 It of water) were efficient under both systems and did not produce russet on fruits: Saprol 20% EC (Triforine 20) 70 cc; Dodine 65% WP 90 g, from green tip to early bloom, and 60 g there on; Difolatan 4F (Captafol) 150 cc, in a single application on green tip, followed by Captan 50% WP 250 g, or Dodine 60 g, or Saprol 70 cc, at early peta! fall, and by Dodine or Saprol, there on; Dimazin 80% WP 200g; Pallinal 72,5% WP 250 g, from green tip to early bloom, and 200 g there on; Baycor 25% WP 75 g, up to early bloom, and 50 9 there on; Dodine 90 g, alternated with Cercobin M 70% WP 60 g; Dodine 30 g + Cercobin M 50 g. Moreover, Maneb 80% WP 240 g and Folpet 50% WP 200 g, not tried under the calendar system, and Saprol 110 cc, tested at different doses under the calendar system, were also effeetive under the climatic conditions system.
The number of applications with the calendar system varied from 7 to 10, according to the treatment's characteristics; with the "climatic conditions" system, this number was similar in some of the seasons, but in others it was reduced to 4 or 5. Before this study, growers had been applyin |
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