Fungicide Timing Key to Better White Mold Control

North Dakota State University Plant Pathologist Michael Wunsch says small changes in fungicide timing and application can significantly improve white mold control in dry beans and soybeans. Wunsch said years of research show many growers are missing the optimal application window, limiting fungicide effectiveness against the disease. “We have worked to address when fungicides should be applied, when conditions favor white mold as the crop enters bloom, and also how they should be applied, with an emphasis on fungicide droplet size,” Wunsch said. “What we have learned is that we can make significant gains by slight modifications to our existing strategies. Fungicide application timing is very important to pay very close attention to the growth stage.” Wunsch said correct timing depends on crop type and whether a grower plans one or two applications. “If you are going to make a single fungicide application, you want to wait a little bit longer because you want that canopy to grow a bit more, and that will extend your protection a little bit longer through the window of maximum susceptibility,” he said. “Essentially, we get a 50 percent or more increase in the yield gain from the fungicide when we do this, and on soybeans, adjusting droplet size can increase yield gains another 50 to 100 percent.”