Powdery mildew of soybeans has become more of a problem over the last several years in harvests throughout the world. Caused by the fungus Micropaera diffusa, powdery mildew in soybeans can wreck serious havoc amongst these precious crops. Powdery mildew thrives most readily in cool temperatures paired with low humidity. As such, this is the time of year that growers must be extra careful about, especially in regards to their soybean crops. Late-planted soybeans are the most vulnerable to powdery mildew infestations as the timing of cooler weather late into the grow season alters soybean yields. Due to the fact that powdery mildew epidemics occur every few years, growers are warned that another invasion could be coming at any time this winter season.

Identifying powdery mildew infestations on your soybean crops early is essential to being able to eradicate the issue before the entire harvest is lost. Look for powdery mildew to be present on stems, cotyledons, pods, and most notably on the upper surface of leaves. Unfortunately, symptoms of powdery mildew are far less noticeable compared to the signs of the pathogen. Be aware of the following symptoms of powdery mildew on your soybeans:

• Interveinal necrosis
• Yellow and green islands on the leaves
• Leaf blades crinkle
• Necrotic specks
• Defoliation

It is also important to note that while powdery mildew certainly threatens your soybean crops, the disease is often paired with additional pathogens. As such, it may be difficult to determine just how much powdery mildew was involved in the damage compared to other pathogens. When compared to untreated crops, soybeans yield losses when treated with an organic fertilizer faired far better than those who were untreated. Using a powdery mildew killer, growers are encouraged to regularly apply organic fertilizer to their soybeans in order to prevent the onset of a powdery mildew invasion.