Studies of Didymella bryoniae: The influence of nutrition and cultural practices on the occurrence of stem lesions and internal and external fruit rot on different cultivars of cucumber
Cucumber plants of different cultivars grown under various levels of nutrient supply, climatic conditions and different pruning practices were inoculated withDidymella bryoniae (Auersw.) Rehm. Increased concentration of the nutrient solution in the rockwool, slabs leading to a higher amount of dry matter content in the plant tissue resulted in a lower percentage of internal and external fruit rot in the cultivars Daleva and LD 290/82 (Dæhnfeldt), and in lower percentage of internal fruit rot in cv. Aminex, whereas the effect on cv. Dalibor was insignificant. Differences between cultivars were observed, cv. Dalibor showing the highest level of resistance against internal fruit rot and lowest incidence of nodal and internodal lesions.
Separate factors appear to affect the establishment of the pathogen in the nodal tissue and its invasion of the internodal tissue. By raising the temperature to daytime level 3 h before sunrise, the risk of extended periods with high humidity was limited and the incidence of internal fruit rot was reduced. An increased incidence of nodal and internodal lesions and external fruit rot was observed at reduced pruning, leaving wilted leaves and shoots on the plants.
Additional keywordsGummy stem blight glasshouse cucumber flower infection resistance climatic conditions pruning, nodal infection internodal infection dry matter content nutrition cultivar differences
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