Effect of temperature and water regime on the release and potential infectious period of ascospores of <i>Zasmidium citri‐griseum</i> and <i>Amycosphaerella africana</i> from citrus leaf litter

Abstract Citrus greasy spot, caused by Zasmidium citri‐griseum , has been reported in different citrus‐growing areas in America. Greasy spot‐like symptoms have also been described in other regions associated to Amycosphaerella africana . Ascospores are considered the main way of multiplication in both fungal species. The effects of temperature and water regime on ascospore release and potential infectious periods of Z. citri‐griseum and A. africana were studied under controlled conditions. The optimal temperature for ascospore release was 24.35°C for Z. citri‐griseum , and 17.66°C for A. africana . The optimal water volume for ascospores release was 5.39 mm for Z. citri‐griseum and 1.23 mm for A. africana . The potential infectious period for Z. citri‐griseum showed the end of the lag phase for ascospore release at 3.21 days and the end of the exponential phase at 28.94 days. Thirty‐five wetting and drying cycles were required to exhaust the ascospores deposit in the citrus leaf litter. For A. africana , the end of the lag phase occurred at 2.82 days and the end of the exponential phase at 22.94 days. Thirty cycles were required to exhaust the ascospores. The information obtained about the effects of temperature and water regime on ascospore release and potential infectious period in citrus leaf litter contributes to better understand the biology of Z. citri‐griseum and A. africana and improve disease control.