'Tis the Season for white mold

‘Tis The Season!  For white mold, that is…. 

Recent rains have increased the potential for white mold infection in the area.  Soybeans that are flowering are susceptible to white mold infection now until flowering ceases.  Infections happen through the dead flower tissues on the soybean plant.  Applying fungicides now for white mold is a key management step, especially in areas where there has been a history of white mold. 

When scouting fields for white mold, you may happen across “germinating” white mold sclerotia, which have little mushroom-like, trumpet-shaped structures on them.  These structures are called apothecia, and are the spore-producing structures for white mold.  Presence of these indicate that white mold spores are in the air and there is a risk of infection.

However, there is a common look-alike out in the field as well.  The birds nest fungi produces a rough, tan-colored structure that looks a little like a white mold apothecia.  When open, these structures look like a small “nest”, including containing reproductive structures that look like little eggs - thus the name of the fungi.  Birds nest fungi are harmless, are not a pathogen of the soybean plant, and are simply eating away at organic material in the soil. Be alert even if you only find the birds nest fungi, as the conditions that favor the birds nest fungi also favor white mold development.

A member of our local agronomy team, Brad Cihak of Langford, took an excellent photo of a group of birds nest fungi (second picture) while out scouting for white mold.

Soybean white mold. The Sclerotia is "germinating", producing what is called an apothecia, which produces the spores. Photo: APSnet.

Birds nest fungi. These harmless fungi are  simply eating away at the organic matter. They are not a pathogen in any form and are not white mold apothecia. The reproductive structures for this little fungus are the little hard "eggs", called peridioles, that are in the middle of the "nest." Immature "nests" are covered with the veil.
Photo: Brad Cihak, Agtegra Langford.

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