ROANOKE, Ill. – July soybean futures plunged by as much as 84 cents per bushel last week, dragged down by pressure from a wetter forecast. In order to preserve profits, producers should double down efforts to scout fields and apply timely fungicides, particularly for white mold at the flowering R1 stage.

This is according to ILSoy Envoy and certified crop advisor (CCA) Jason Carr, who is a technology development representative for Bayer in Bloomington, Ill. He stressed that farmers should begin scouting for white mold as soon as soybean plants are flowering, especially following last week’s precipitation in central Illinois and areas of the Corn Belt.

“Typically the timing for most soybean fungicides is R3, and we’re just starting to ease into R1 on our earliest planted beans. We planted test plots on March 10, April 6 and every two weeks between then and now. Those planted later will be flowering in a week or two,” said Carr, referring to Bayer test plots near Roanoke in Woodford County. “As pods begin to form in R3 is when we typically begin to apply fungicides, unless we are in an area such as northern Illinois or northern Indiana where there are issues with white mold. With white mold, the fungicide will need to go on right when the plant begins to flower in R1.”

In areas of heavy white mold infestation, it may be necessary to apply two fungicide treatments to plants in the R1 growth stage followed by another application at R3. Caused by the fungus Sclerotinia sclerotiorum, white mold can substantially reduce soybean yields when climatic conditions and management practices favor high yield potential. The fungus can also pose significant problems in the northern corn-growing region.

Bayer field research has concluded that in addition to causing yield loss, white mold can affect seed quality and seed production. It is sometimes observed in harvested grain, leading to price discounts for foreign material delivered at the elevator. Soybean seed can also be infected, resulting in reduced germination and provide a source of inoculum if planted into fields with no history of white mold.

The fungus can be identified by white, fluffy, cottony growths on the outside of stems and on pods. Symptoms also include wilted leaves, stems that appear “bleached” and shredding of stem tissue. In addition, sclerotia, small black structures that resemble mouse or rat droppings, are often visible on and inside plants that have been affected by white mold.

In his role as CCA, Carr has sometimes been asked what time of day is best to apply fungicides. While some producers prefer to apply products in late morning or early evening, Bayer research has shown that applications made during times of high atmospheric humidity – rather than certain times of the day – may provide optimal protection for plants. “There can be a little bit of difference in efficacy based on the humidity level. In a higher humidity setting we are going to have less evaporation of the product, therefore it is going to stay on the leaf longer and (be absorbed) better,” Carr said.

Current fungicide performance studies are providing producers with more knowledge and options than ever before. Bayer crop scientists are currently conducting research trials and collecting data at more than 85 locations in Illinois and elsewhere to gauge just how great a yield bump properly-applied fungicides can provide.

“Last year we saw the fungicide give a yield increase in 93 percent of the instances it was sprayed compared to the untreated plants. 82 percent of the time the increase was 2 bushels or greater, which provides a positive return on investment for the spraying,” said Carr, who recommends mixing a small portion of insecticide into each spray tank of fungicide, especially during R2-R4 applications.

“This is due to the relatively inexpensive cost for the insecticide, and looking back to last year when we had an unexpected issue with brown leaf beetles and had a real use for the insecticide,” he explained.

Carr reported that soybean fungicide trials held at Bayer’s Roanoke facility and elsewhere have been pleasingly consistent for the past several years, adding value to nearly every bushel of soybeans.

“Even if we look back all the way to 2019, which was a very different year with a huge portion of the crop planted in June, we sprayed fungicide very late in the year. We saw a huge yield response to that fungicide. I attribute this (versatility) to the range of outstanding new products that are now on the market that we didn’t have six or eight years ago,” he said. “So if you had looked at fungicides for soybean applications a few years ago and didn’t have satisfactory results, it may be time to look into some of the new products and reconsider your decision, especially in the commodity price environment we have currently.”

Prior to his hiring by Bayer, Carr spent a decade in soybean breeding with Monsanto as part of a team developing commercially successful varieties in RM groups 2 and 3. He holds a master’s degree in molecular genetics and a bachelor’s degree in natural resources and environmental sciences from the University of Illinois. Agronomic questions can be addressed to: jason.carr@bayer.com.