Harvest 2013: Another Set of Extremes

October 1, 2013 12:00 AM

(Shared by Charles Hurburgh, Iowa State University)

This sounds like a broken record, but we are looking at yet another harvest driven by weather extremes and combinations that are hard to predict. The major events were the extremely late planting in very wet soils, followed by an almost complete turnaround in many places to a steadily growing drought condition.

In July, the market believed that our major harvest risk would be very wet and late crops vulnerable to even an average frost. By Sept. 1, protracted heat changed the picture completely to the point where corn harvesting has begun in several markets. The quality and management forecast now differs sharply between corn and soybeans.


The recent extension of 90+ temperatures with inadequate rainfall has rapidly increased maturity of corn regardless of planting date. This demonstrates the principle that timing of events is at least as important as the average conditions. On average this year was "average" temperature and rainfall. However, corn quality is driven by conditions during grain fill. Kernels are small and shallow; the extent of kernel fill will be variable depending on timing of rains.

Last year drought-stressed plants put unexpectedly large amounts of dry matter into kernels, resulting in the highest test weights and protein contents in many years. Areas that had enough rainfall to continue root development in June and July may experience the same result, but shallower rooted plants likely will have reduced fill and, therefore, lower test weights.

Test weight is one of two reliable indicators of storability, the other being the variation in moisture at harvest. Moisture variation will be an issue this year; even within the same planting date, there are large differences in maturity within fields or even the same rows. If there are large areas of replants, harvesting around them is a good option, but within fields there is little choice but to harvest straight through, which creates challenges for drying and handling.

Recognize that early harvest will happen in warm weather. Rapid drying and cooling will be critical to preserving the storage life of 2013 corn. Actions in the first few days after harvest can either preserve or waste the future storage life of grain.


Soybeans are small but will probably be dry, except those planted quite late (June and after). Late-planted soybeans may still have some frost risk, especially in areas that received enough rain in August and early September to slow down the maturing process. Growth in the late season will mean harvesting with green stems and mixed quality. We will have more information on frost impacts and handling of frost damage if this problem occurs.

Harvest Planning and Preparation

Scout fields for fungal infections. Until the very recent hot weather, fungus and related mycotoxin problems seemed unlikely. However, deteriorating conditions and repeated small rains may encourage field fungi. It is important to understand which fungus can produce which toxin.

There is a video tutorial on mycotoxins on the Iowa Grain Quality Initiative website.



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