ABSTRACT


Iris Carreño I.1 y Adriana Pinto de Torres1
 
Isolates of Venturia inaequalis (Cke.) Wint. from an apple orchard (Curicó, Chile) in which Benlate and Cercobin had given poor scab control were determined tolerant in culture to these fungicides. New lesions, free of contamination and germinated spores were chosen and also monosporic cultures were utilized. Spores of V. inaequalis from new lesions on fruits were incubated at 20-22°C in PDA medium with 5 ppm BenomyI for 24 hrs; germinated spores were transfered toanothers PDA medium containing 5 ppm Benomyl. These isolates were tranfered to PDA medium containing 0 - 5 - 100 - 250 and 500 ppm Benomyl and MethyI tiophanate. The isoIates from sprayed orchards deveIoped and sporuIated in 250 ppm BenomyI and 5 ppm Methyl tiophanate forming typicaI colonies, demonstrating 10 fold tolerance over susceptible strains isolated from fruits obtained from never sprayed trees.
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1Ings. Agrs. Fitopatólogos, Programa Frutales y Viñas. Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.