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 n utrient supply, climatic conditions and different pruning practices we re inoculated with Didymella bryoniae (Auersw.) Rehm. Increased concen tration of the nutrient solution in the rockwool slabs leading to a hi gher amount of dry matter content in the plant tissue resulted in a lo wer percentage of internal and external fruit rot in the cultivars Dal eva and LD 290/82 (Daehnfeldt), and in lower percentage of internal fr uit rot in cv. Aminex, whereas the effect on cv. Dalibor was insignifi cant. 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 dayti me level 3 h before sunrise, the risk of extended periods with high hu midity 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 s hoots on the plants.