Fight Back Against White Mold in Beans and Chickpeas

Fight Back Against White Mold in Beans and Chickpeas

White mold is one of the most yield-limiting diseases in soybeans, dry beans, and chickpeas. Under the right conditions, losses can climb past 20–30%. Since pressure varies year to year, it’s not always obvious when it will hit hardest, making proactive management essential for protecting profitability.

For bean growers in the Great Lakes (WI, MI, OH, NY) and Ontario regions, the risk is especially high. Cool temperatures (20–27°C / 68–80°F) and prolonged high canopy humidity create ideal conditions for infection, particularly from planting through flowering.

The survival rate and life cycle of the white mold pathogen, Sclerotinia sclerotiorum, justify that fungicide applications are equally important to fertilization. After the detection of white mold has occurred, the pathogen will have been primed for infecting plants for years to come.

Life Cycle of White Mold Pathogen

White mold spores are released from small mushrooms in the soil, which land on fallen flower petals during the early reproduction stage. The spores use the decaying flower as food and infect the plants. White mycelium will begin to appear a few weeks later, followed by early signs of active infection, like the classic “shepherd’s crook” or wilting at the top of bean plants (see photo 1). But by the time you see symptoms, the pathogen is already established. Next, the pathogen evolves into its reproductive body, a hard, black vegetative structure called sclerotia. These are commonly described as "rat droppings" (see photo 2) and covertly survive in soil for more than five years.

When conditions are right, the “rat droppings” germinate and form small, funnel-shaped mushrooms that are difficult to see in the soil below dense bean canopies. They release spores into the canopy, land on flower petals, which then stick to the stems and create the perfect entry point for infection by mycelium. From there, the disease spreads quickly, clogging stems and leading to plant death (see photo 3).

Start With the Right Strategy

Managing white mold includes tactically selecting the right seed, row width, and plant population. These decisions can greatly influence the environmental humidity created in the field: plant spacing and canopy density that allows airflow will diminish humidity. For example, early-row closure, often found in 15-inch rows, is favorable to white mold.

Low rainfall and low humidity prevent spores from sticking to the stem, flower, and petals. It is recommended to eliminate white mold spores before the flowering window through a fungicide application at R1.

Best Practices for Fungicides

Fungicide applications remain one of the most reliable tools when applied at the right time, in the right location, with the right mixture, and the right droplet size.

Timing:

• • Infection primarily occurs during R1–R2 (beginning to full flowering)
  • Spores colonize senescing flower tissue, then invade stems
  • Later applications (R3 or beyond) are significantly less effective once infection is established

Placement:

• • Target the lower canopy (at R1)

Application Set-Up:

• • Use adequate water volume (15–20 GPA for ground application)
  • Medium-sized droplets improve canopy penetration

Product Strategy:

• • Prothioconazole provides consistent, systemic control and yield protection
  • Fluazinam delivers strong preventative activity and supports resistance management
  • Broad, dependable performance comes from combining these complementary actives

For growers facing recurring white mold pressure, a program built around these complementary actives—applied at the right time—can be the difference between low to average yields and protected profit potential.

For an impactful fungicide application, schedule it early and target flowering around R1-R2. During wet, cool growing years, two applications are recommended to reduce disease pressure and preserve yield.

Modern Solutions for White Mold Management

Prothioconazole, the active ingredient found in Vive’s Phobos® FC fungicide (FRAC 3, DMI), is a valuable foundational active in white mold programs due to its reliability, compatibility in mixtures, and activity on Sclerotinia.

Phobos FC, known for its seamless mixing with liquid fertilizers and other crop inputs, also provides:

• Strong systemic movement that improves protection within the canopy.
• Broad-spectrum activity across multiple foliar soybean diseases, such as Frogeye leaf spot and Cercospora leaf blight.
• Uniform leaf coverage through even active ingredient distribution.
• Stronger drying to help resist rain wash-off.
• Consistent yield protection under moderate to high disease pressure.

Fluazinam (FRAC 29) is a contact fungicide with strong activity on Sclerotinia. It excels in protecting stems and petals through its “plastic wrap” action against white mold.

This unique mode of action helps manage resistance risk and has delivered strong performance when applied at R1-R2, before infection starts.

Combining these actives delivers complementary strengths:

Conclusion

White mold is unpredictable, but your management strategy shouldn’t be. The most successful programs are built on understanding field history, managing canopy conditions, and making timely, targeted fungicide applications.

Vive Crop Protection’s solutions are built to fit seamlessly into existing programs, delivering superior protection when and where it's needed.

Learn more about Vive’s crop protection portfolio: https://www.vivecrop.com/products