Epidemiological studies on Apiosporina morbosa on sour cherry
Apiosporina morbosa (EPPO A1 quarantine pest) is widely distributed on sour cherry (Prunus cerasus) in southern Ontario, Canada. It can significantly reduce production in important sour cherry-growing areas. In Ontario, studies were carried out in sour cherry orchards on the relationships between ascospore discharge from excised black knots and environmental conditions. The final goal of these studies was to determine the best timing for fungicide applications. Ascospore discharge was monitored over several periods (May 92 and 93, March, April, May 94 and 95). Rain, temperature and wetness duration were monitored and a regression model was developed to assess the relationships between discharge and environmental conditions. Results showed that the release of ascospores depended on rainfall and temperature, but not on wetness duration. Peak ascospore release occurred from May to mid, late June. Large ascospore release followed precipitation of at least 10 mm at a temperature of at least 11°C. Maximum occurred at 17 °C, and at any given temperature, discharge increased with increasing amount of rainfall.
McFadden-Smith, W.; Northover, J.; Sears, W; (2000) Dynamics of ascospore release by Apiosporina morbosa from sour cherry black knots.
Plant Disease, 84(1), 45-48.