Indiana Prairie Farmer publishes a column written by Tom Bechman with the help of CCAs for CCAs and their clients. With permission from Prairie Farmer we are posting these Soybean and Corn Pest Beat articles on the CCA website. Many thanks to the authors and the support of Indiana Prairie Farmer.
Soybean Pest Beat Articles
Be proactive when battling white mold
The Indiana Certified Crop Adviser panel includes Gene Flaningam, Flaningam Ag Consulting, Vincennes; Carl Joern, Pioneer, Lafayette; and Greg Kneubuhler, G&K Concepts, Fort Wayne.
Last year, we were faced with heavy white mold pressure following a damp spring in my area. We’re reducing seeding rates to 100,000 seeds per acre. What else can we do to be proactive this year?
Flaningam: Review soybean disease ratings for white mold with your seed salesperson. Choose a variety that has the ideal maturity and plant characteristics for your region. Reduce seeding rates to get more airflow through the plant canopy. Consider planting 30-inch-row soybeans to increase canopy airflow.
Joern: Cutting seeding rates is a good first step. 100,000 seeds per acre as your seeding rate is a bit low. Shoot for that as your targeted final stand. White mold thrives in dense, early-closing canopies that trap humidity, so anything that improves airflow and light penetration helps reduce risk.
Beyond population, start with variety selection. There isn’t true resistance, but there are meaningful differences in tolerance. Choosing a soybean with stronger white mold scores slows disease development and limits damage, especially in fields with a history of pressure.
Manage the canopy environment. You’ve already lowered seeding rate, which research shows can influence white mold more than row spacing. Planting in wider rows or avoiding overly aggressive populations can help, but only in fields where disease risk is high. Don’t sacrifice yield unnecessarily. Also avoid practices that create overly lush growth, like excess fertility and heavy weed pressure.
Think long-term with rotation and tillage. Rotating to non-hosts like corn or small grains can help reduce inoculum. No-till has also shown benefits because it leaves sclerotia at the surface, where they deteriorate, rather than burying them into the germination zone. And make sure equipment and seed are clean. Sclerotia can spread on combines.
Have a protection plan ready if conditions turn cool and wet at flowering. Foliar fungicides labeled for white mold work best preventively at early flowering before infection occurs. Coverage into the lower canopy is critical. In high-risk years, a second pass may be justified because products only protect for a couple of weeks.
Kneubuhler: You’re already starting off on the right foot by lowering seed populations. White mold thrives in dense canopy, which can stay wet longer. It can also survive for five-plus years in the soil and show up in future seasons.
First, look for varieties with stronger tolerances to white mold and possibly varieties that may be less bushy or more upright in nature. Second, tweak row spacing to limit the impact from white mold. That might mean planting 30-inch rows in extreme cases. But even 15-inch rows help mitigate the risk. Third, consider applying fungicide during R1 or R2. The infection enters the plant through the blooms. Consider even a second pass in high-pressure fields. Active ingredients to look for include boscalid, fluazinam or pydiflumetofen.
