Time, temperature, and moisture effects on incidence of seed infected by Caloscyphafulgens in Sitka spruce cones

Abstract

The effects of time, temperature, and moisture on incidence of seeds infected by Caloscyphafulgens (Pers.) Boudier in Sitka spruce, Piceasitchensis (Bong.) Carr., cones was determined by incubating pathogen-inoculated cones on forest duff and subsequently storing them under conditions used to air dry cones before seed extraction. In the field, the percentage of diseased seeds increased gradually and reached about 10% over the 8-week incubation period. This increase was about equally well correlated with increasing time, cone moisture content and cumulative rainfall, decreasing temperature, and all combinations of these parameters. The percentage of diseased seeds did not increase when field-incubated cones were subsequently stored (air-dried) up to 8 weeks, probably because cone moisture content decreased.