Signup to receive email updates




or follow our RSS feed

Authors

Angie Peltier


Angie Peltier
Former Extension Educator, Commercial Agriculture



follow our RSS feed

Blog Banner

Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. White mold is favored by cool, wet, humid weather and flowering soybeans with a dense canopy.
click image to view 3 more

Did Western Illinois dodge the bullet for white mold in soybean this year?


Fungus survey. The University of Illinois is taking part in a fungus survey organized by Dr. Kiersten Wise at Indiana's Purdue University through funding provided by soybean check-off dollars and the North Central Soybean Research Program (NCSRP). As part of this survey, participants scout two soybean fields that had been planted to corn last year, one field that is no-till and one that is tilled, looking for fungi. The Northwestern Illinois Agricultural Research and Demonstration Center (NWIARDC) is one of the scouting locations.

Fungi that produce what we would call "mushrooms" live most of their lives inconspicuously, as thin white threads called mycelia. Mycelia grow through organic matter in the soil, secreting enzymes that degrade organic matter and release nutrients that the mycelia then absorb.

Specific environmental conditions favor the germination of fungal fruiting bodies or mushrooms. Mushrooms serve an important purpose in the fungal life cycle, allowing the fungus to reproduce sexually. Sexual reproduction results in the release of spores that help these stationary fungi escape their living space and spread throughout the environment on wind currents.

White mold fungus. The fungus that causes white mold of soybean is called Sclerotinia sclerotiorum. This fungus spends its life in the soil as hard, black structures called sclerotia. Sclerotia, which resemble mouse droppings, help the fungus survive over harsh winters and dry soil conditions. Under cool, wet, humid, and low-light conditions (conditions which are more likely to occur under a full soybean canopy) sclerotia germinate to produce small, cup-shaped mushrooms called apothecia (Figure). Apothecia release sexual spores called ascospores that can infect soybean. Soybean plants are susceptible to infection during flowering as ascospores use dead and dying flowers as a food source and then infect the soybean stem at nodes (where leaves meet the stem).

White mold disease in soybean. Symptoms of white mold are typically scattered in patches throughout the field and include lesions that start at stem nodes. Lesions initially have a water-soaked appearance and become bleached and stringy with time (Figure). The name "white mold" came about because sometimes, under very wet, humid conditions, a white, fluffy mold can be seen growing out of the lesions. Severe infections can result in plant wilt and death and significant yield loss.

What about disease risk in 2013? The NCSRP-funded fungus survey takes place every two weeks throughout the growing season. Two weeks ago, a detailed search under the soybean canopy revealed no fungal fruiting bodies. However, this week a search of the same fields revealed many fungi, including the pathogen that causes white mold, Sclerotinia sclerotiorum (Figure).

The most recent USDA-NASS Crop Progress and Condition report released August 5th, stated that as of August 4th, only 88 percent of the soybeans in the western Illinois crop reporting district (which includes Monmouth and the NWIARDC) are blooming. Approximately 39 percent of soybeans have begun setting pods. This means that much of the 2013 soybean crop in western Illinois may still be susceptible to white mold.

Dr. Carl Bradley, University of Illinois Plant Pathology Specialist, recently wrote an article for the Bulletin, in which he detailed recommendations and results of recent white mold fungicide trials and a link to recently developed resources to manage white mold.

Anyone who is interested in a hard-copy of the white mold management guide is urged to either stop in to the Warren County Extension Office and pick up a copy or contact me to receive one through the mail.



Please share this article with your friends!
Share on Facebook Tweet on Twitter Pin on Pinterest

COMMENTS



Email will not display publicly, it is used only for validating comment