A method for quantification of Pythium aphanidermatum in cucumber roots and suitable inoculum densities for epidemiological studies.
A method for the quantification of Pythium aphanidermatum density in cucumber roots based on an indirect enzyme-linked immunosorbent assay (ELISA) was established and tested. This approach was applied in three experiments under various environmental conditions. In addition, different inoculum densities were applied to vary the disease severity but also, to search for suitable inoculum densities in long-term epidemiological studies. Cucumber plants were grown in containers with aerated nutrient solution in a growth chamber at air temperatures of 15, 20, 25 and 30˚C, and were inoculated with 0, 10, 10and 10oospores of P. aphanidermatum per litre nutrient solution. The pathogen density in the roots increased with inoculum density and temperature and resulted in growth reduction of the cucumber plants. Clearly, low temperatures delayed the development of the disease in the plant, while high temperatures combined with high inoculum densities led to sudden death of some plants. Therefore, inoculum densities not higher than 10oospores per litre should be applied in long-term experiments. Independent of inoculum density and temperature, correlations were established between the mycelium density in the roots and the crop biomass, indicating that the indirect ELISA produces robust estimates of P. aphanidermatum density in cucumber roots under various conditions.
Kyuchukova, M.A.; Büttner, C.; Gabler, J.; Bar-Yosef, B.; Grosch, R.; Kläring, H.-P. 2006. A method for quantification of Pythium aphanidermatum in cucumber roots and suitable inoculum densities for epidemiological studies. Journal of Plant Diseases and Protection 113 (3), 113-119.