Crop & Pest Report


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Is Corn Development Catching Up? (07/11/19)

In the most recent NASS Crop Progress report, about 80% of the corn crop was rated good to excellent.

In the most recent NASS Crop Progress report, plsc.2about 80% of the corn crop was rated good to excellent. However, much of the corn was planted late this year and that, coupled with abnormally cold temperatures in May, has caused some concern about how the crop might finish the year. Since we are about a third of the way through the season (as far as GDDs are concerned) I thought it was a good time to assess when the crop might mature this fall.

In Table 1, I have summarized GDD accumulations for this season (and normal GDDs) assuming May 1st and May 22nd planting dates. The latter date was used as it was when about 50% of the corn was planted in North Dakota this year. As expected, planting date has had a significant effect on the number of GDD available with about 115 more GDD available to the earlier planted crop. However, due to the cold temperatures in May in this year, that difference was much less would be normal for the same period (~190 GDDs are the normal difference compare to 115 this year).

GDD accumulation since May 22 have been very similar to the long-term average, which suggests that we are not falling behind the normal, nor are we catching up. Simulations from in the U2U Decision Support tool for GDDs, predict that the maturity of early planted corn will be behind normal (due to the cold May), but depending on the RM of the hybrid grown, there is a reasonable chance that it will mature early enough for reasonable dry down before normal harvest.

For the later planting date, maturity is likely to occur in October, later than is considered optimum as far as field drying is concerned. This is particularly the case if a full season hybrid was used, even though planting was delayed. Data on the attached table are averages and should be viewed as such. The GDD tool, does produce a range of dates around the average and illustrate what is possible, given the variability in weather between years. The recent warmer weather has not been sufficient to catch the crop up to an more ideal stage; warmer than average temperatures for the remaining two thirds of the season are needed to ensure a good finish to the corn crop this year and given the variability of past weather, there is still a reasonably good chance that could occur.



Joel Ransom

Extension Agronomist, Small Grains and Corn

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