Estimation of Seasonal Ascospore Production of Mycosphaerella populorum

1991

S. 1349-1353

4 Abb., 16 Lit. Ang.

Unselbständiges Werk

200089536

A model was developed that estimates ascospore production by Mycosphaerella populorum Thompson in response to degree-days. Spore production and release in two field seasons were monitored with an ascospore liberation tunnel and Vaseline-coated slide traps, respectively. Ascospore production in a moist environment and under controlled temperatures was monitored in the laboratory with the liberation tunnel. Ascospores were produced in the laboratory for periods of 192, 98, and 74 days at 9, 16, and 21C, respectively, after initial ascospore maturation. Field and laboratory ascospore collection data were linearized with a Gompit transformation. Regression coefficients on the linearized data were greatest when a degree- day base of 0C was used. Slopes of the regression lines (k-values) developed from laboratory and field (1984 season) data were not significantly different. The k-values from laboratory data and data collected during the 1985 growing season were significantly different. The difference was attributed to dry weather during the period of ascospore production and release. The laboratory regression model could be used to predict ascospore production during the growing season after initial ascospore maturation if adequate moisture is present and if degree-day accumulation is predicted.