VIEW ARTICLE

Disease Control and Pest Management

A Model to Estimate the Maturity of Ascospores of Venturia inaequalis. David M. Gadoury, Graduate research assistant, Department of Botany and Plant Pathology, University of New Hampshire, Durham 03824; William E. MacHardy, associate professor, Department of Botany and Plant Pathology, University of New Hampshire, Durham 03824. Phytopathology 72:901-904. Accepted for publication 14 January 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-901.

The rate of maturation of ascospores of Venturia inaequalis was directly proportional to temperatures ranging from 6 to 20 C. There was a linear relationship between the probit of ascospore maturity and degree-day accumulation (base = 0 C) from the first appearance of mature ascospores. This relationship allowed the formulation of a simple linear statistical model of ascospore maturation. The model can be used to estimate the cumulative percentage of matured ascospores, given the degree-day accumulation since the first appearance of mature ascospores. The model was verified by comparison to its component data sets and was validated with additional field and laboratory observations of ascospore maturity.