Comparison of strobilurin type fungicides to control soybean seedling pathogens

• Published in: Phytopathology Vol. 98; no. 6; p. S50
• Main Authors: Ellis, M L, Broders, K D, Dorrance, A E
• Format: Journal Article
• Language: English
• Published: 01.06.2008
• Subjects: Fusarium graminearum; Phytophthora sojae; Pythium
• ISSN: 0031-949X

Seedling diseases in soybean fields in Ohio have increased over the past decade. Most likely due to the occurrence of cool, moist soil conditions shortly after planting that delay seed germination, and favor growth of soil-borne pathogens, such as Phytophthora sojae, Pythium spp. and Fusarium graminearum. In this study azoxystrobin, trifloxystrobin, and pyraclostrobin fungicides were compared for their efficacy to control six isolates of F. graminearum, two isolates of P. sojae, and 17 isolates of Pythium, with each isolate representing a different species. Plate assays, which measured the mycelial growth of each isolate at concentrations of 0.01 ppm, 0.1 ppm, 1 ppm, 10 ppm, and 100 ppm were completed for each of the fungicides. The results indicate that azoxystrobin and pyraclostrobin are effective in reducing growth of the 17 different Pythium spp. starting at 10 ppm, while trifloxy-strobin showed little control even at the highest concentration. The fungicides showed no significant control in reducing mycelial growth of P. sojae or F. graminearum isolates. These results indicate that along with other cultural control methods, seed treatments, using azoxystrobin and pyraclostrobin compounds, can be effective in limiting growth of 17 different species of Pythium isolated from diseased soybean seedlings in Ohio.