Effect of Bitertanol, Fenarimol, and Urea as Fall Treatments on Venturia pirina Ascospore Production. B. A. Latorre, Departamento de Sanidad Vegetal, Facultad de Ciencias Agrarias y Veterinarias, Universidad de Chile, Casilla 1004, Santiago. G. Marín, Departamento de Sanidad Vegetal, Facultad de Ciencias Agrarias y Veterinarias, Universidad de Chile, Casilla 1004, Santiago. Plant Dis. 66:585-586. Accepted for publication 8 October 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-585.

A significant reduction in the ascospore productivity of Venturia pirina was obtained with a late-season application of bitertanol, fenarimol, or urea. The best inhibition was achieved with fenarimol at 30 ml/100 L, followed in order by bitertanol at 60 g/100 L and 2% urea. The first ascospores were caught on untreated controls on 27 August when trees were at the green tip stage of fruit bud development; thereafter, a continuous emission was recorded until late December. The overall discharge period lasted more than 17 wk.

Keyword(s): Pyrus communis.