YIELD OF CUCUMBER INFECTED WITH PYTHIUM-APHANIDERMATUM WHEN GROWN WITH SOLUBLE SILICON

Two experiments were conducted in separate locations, one at Universite Laval in eastern Canada (Quebec) and one at the Agassiz Research Station in western Canada (British Columbia), in an attempt to determine the effectiveness of soluble silicon (Si) against cucumber root disease caused by Pythium aphanidermatum Edson. Long English cucumber (Cucumis sativus L. cv. Corona) plants were grown either in a standard nutrient solution or in nutrient solutions supplemented with 1.7 nM (100 ppm) Si and inoculated or not with the pathogen. Supplying the solutions with 1.7 mm Si significantly reduced mortality and disease symptoms attributed to infection by P. aphanidermatum. Grown in presence of Si, plants infected with P. aphanidermatum showed a significant increase in yield, marketable fruit, and plant dry weight compared to Si-nonamended and infected plants. These beneficial effects were observed under both experimental conditions. The fruit yield of noninoculated plants was not affected by the presence of Si in the Agassiz experiment. However, Si-amended control plants were more productive in the experiment conducted at Laval, apparently because of contamination problems, which indicates that Si beneficial effects are most likely related to disease management.