Stalk rot and field drying

October 7, 2015 4:24 PM
Blog Post

By: Clarke McGrath

Stalk rot issues have only gotten worse in recent weeks; in some cases, a lot worse. Stalk rot and resultant standability challenges have reportedly been issues across much of the state, and are not hard to find in most of southwest and west central Iowa.

Risk vs reward
If you can scout your corn well and find areas that have good stalk quality, then some field drying may be a good plan of attack. For fields with significant stalk rot and risk of lodging, the risk/reward tradeoff of field drying vs pulling it wet and artificial drying is worth a good look. Unfortunately at this time of year, risk (lodging) escalates and reward (natural field drying) typically decreases.

Field drying projections
I’m getting a lot of questions about how much and how fast corn will dry in the field, especially as we head into October. A really good question, with a typical agronomic answer… it depends.

Some previous research conducted in Indiana illustrates our challenges this year; field drying rates are much lower for corn that matures in mid-September (like this year) vs our more typical late-August time frame. The work showed that average daily dry down rates range from about 0.8% per day for grain that nears maturity in late August down to about 0.4% per day for grain that nears maturity in mid- to late September. Unfortunately, for many of us, our grain matured on the later end of that spectrum this year, so expected drying rates would be closer to that 0.4% per day.

As growers aptly point out, the major driver of field drying is the weather, regarding the heat, humidity, and precipitation. Therefore, drying rates for any particular day can vary a lot. If you want a good ballpark average estimate for this time of year, you can expect corn in early October to dry down about 0.5% to 0.75% per day, and by mid-October we are probably looking at 0.33% to 0.5% per day. As we head into later October and November the rate will likely decrease to 0.25% or less.

Purdue’s Dr. Bob Nielsen goes into more detail here

The bright side
On the optimistic side of things, the 7-10 day forecast predicts good things; average to above average temperatures, little precipitation, and light winds- great for harvest and field drying. We also haven’t seen LP prices this low for years, and supplies look strong as long as transportation logistics hold up.

stalk rot
Photo taken by Gary Munkvold


Clarke McGrath On-Farm Research and Extension Coordinator - Iowa Soybean Research Center

Clarke McGrath currently serves as the On-Farm Research and Extension Coordinator.

Prior to joining Iowa State University, McGrath spent nearly a decade as a retail agronomist and manager in the GROWMARK system, earni...