Assessing drought impacts on corn
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Now is the time to make some assessments on the impacts of the drought and heat stress on corn. My observations during the last week indicate that impacts are quite variable but could be greater than they appear from the edge of the field. I have observed a number of different ear development issues related to the drought. In many fields there is some variation in plant development in the row and later plants seem to have more pollination issues. Some fields will have ears that have not pollinated at all, or are just partially pollinated. I have also observed two drought stressed fields with arrested ear development that have minimal cob development in some areas. Earlier hybrids that pollinated before the most stress have some evidence of kernel abortion on the ends of the ear. Several fields I was in have experienced above average deer damage associated with the drought.
Assessing fields for potential yield potential now is critical to make good judgments on the salvage value, need for a crop insurance assessment and the potential grain or forage yields. Assessment of these fields is challenging because of the variability. Be sure to get a representative sample of ears for your assessment. Assessing silage yields is even more difficult since the normal grain equivalent ratios may vary from average values. Normally the grain equivalent is about 7.5 bushels per ton of silage at 65% moisture, but this can vary depending on the season. With drought and pollination problems, this could drop to 2–3 bushels/ton or even 0 in the worst fields. We could also have some short and well pollinated fields that will have above average grain content.
Managing these drought stressed corn fields will likely require some special management this year. This has been complicated by the recent precipitation on many fields, which will cause them to resume growth and development. This will likely create conditions for higher moisture, increased nitrate production, and higher sugar content. The lack of ear development will make monitoring moisture levels more difficult and some fields have varying degrees of dead leaf materials which will complicate things. Measuring moisture this year will be critical.
We have set up a Web site http://www.das.psu.edu/dairy-alliance/resources/drought-survival-guide to catalog some materials for managing drought stressed corn. One item is current factsheet from Dr. Limin Kung at the University of Delaware with some guidelines on managing drought stressed corn, including tips on processing, inoculant use and nitrates.
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