Assessing and Handling Hurricane Damaged Corn
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Dr. Ronnie W. Heiniger, Dr. E. J. Dunphy, Corn Specialists
How much damage was done by Hurricane Bertha?
Over 60% of the North Carolina corn crop was affected in some way by Bertha. Depending on the location, damage ranged from slight to a total loss. We estimate that 10 to 20% of the crop sustained significant damage (50% reduction in potential yield). In situations like these, the goal of producers in affected areas should be to make an honest assessment of the loss in potential yield and determine the best way to handle the damaged crop.
How do I assess hurricane damage?
In order to properly determine damage, it is important to know what developmental stage the crop is in and the remaining development that must take place before the crop reaches maturity. If silks have just emerged, it will take 55 to 65 days before the crop reaches physiological maturity (maximum dry weight, kernels have finished filling but the grain still contains 30-35% moisture). Little, if any, of the kernel weight or resulting grain yield has been accumulated by this stage. Corn at the blister stage (white kernels resembling a blister on the cob) still has 45 to 50 days before it reaches physiological maturity. Approximately, 15 to 20% of the kernel weight and potential yield has been formed at this stage. Corn at the dough stage (thick, pasty inner fluid, embryo is half as wide as the kernel, cob is beginning to turn color) has half of its mature dry kernel weight and yield potential formed. Normally, it will require 30 to 35 days before this crop reaches maturity. Corn at the dent stage (kernels have a dimple on the outer end, cob is mature color) is 15 to 20 days from physiological maturity. Almost 3/4 of the kernel weight and yield potential have been formed.
There are two scenarios for corn damaged in these stages:
SCENARIO 1: If the root and stalk are still intact, and some roots remain in moist soil, the kernels will continue to accumulate dry weight and fill. Corn in this condition will straighten up to some extent with the corn in the silking or blister stages being more resilient and thus able to straighten more than corn in either the dough or dent stages. The stalk above the ear may straighten in corn in either the dough or dent stage, but the portion below the ear is unlikely to straighten which will result in ears almost at ground level at harvest time. There are two primary concerns for corn in this scenario. One is the effect of the root pruning that has occurred on the corn if dry weather is encountered during the remaining fill period . Any prolonged period of dry weather could damage corn more severely when the root system has been pruned. The second concern is the stalk diseases and pest infestations that tend to be enhanced in corn that is lodged or leaning. Given good weather and proper scouting, corn in this scenario can be saved and could still produce high yields. However, harvest will be a problem with ear loss likely to occur at the header.
SCENARIO 2: If the stalk is crushed or broken, little or no dry weight accumulation can be expected since the vascular system is damaged. Corn in this situation at either the silking or blister stage is almost a complete loss. It could be chopped for silage, but with dry weather it will deteriorate rapidly and arrangements for harvesting silage must be made immediately. At the dough stage, corn in this scenario could be harvested for grain, but the grain will be very light and chaffy. Harvest will be accelerated and yields will be reduced 50% or more. Probably the best course of action for corn at the dough stage is to chop it for silage. Again, it will be important to plan to get this done as quickly as possible. The best stage for salvaging corn with stalks that are broken or crushed is the dent stage. Again, the grain will be lighter than normal and yields will be reduced, but approximately 60 to 75% of the crop could be salvaged. Harvest will be accelerated and difficult.
Assuming that I can harvest the corn for grain, what steps should be taken to handle the damaged crop?
There are two things that should be done to minimize the losses that will occur from hurricane damage. First, plan to harvest the grain as soon as possible to minimize the ear loss that can occur as the combine tries to gather the stalks. Harvesting at 25+% moisture and drying to 15.5% moisture will reduce harvest losses considerably when compared to waiting until the corn dries down to 15.5%. This is probably the most important step that should be taken in salvaging this year’s crop. Second, conduct a thorough and intensive scouting program. If diseases or pests are observed consider early treatment where possible or, again, plan to harvest those fields early. Continue to protect your yield potential.
What should be done if I expect to use this crop for silage?
If the stalks are broken or crushed, they will dry rapidly. Quick preparations are needed to use this crop for silage. Chop when the moisture is optimal for your storage structure (concrete stave, sealed storage, or bag). Plan on using a feed supplement when feeding this material as quality will be poor. If the stalks are not broken or crushed, then wait until the crop reaches the dent stage before chopping. This will give you more tonnage and a better quality silage.
Could a desiccant or other chemical be used as a harvest aid to speed dry down?
Don’t use a chemical desiccant (gramoxone or roundup) on lodged corn unless the version of the label you have in your hand says you may safely do so. We don’t know of any products labeled for desiccating corn. Gramoxone has been used as a harvest aid in other crops, but usually has a waiting period before harvest can begin. Roundup is also labeled for other crops, but not for corn. Follow label instructions at all times! It is not clear what advantages desiccation has. Weeds in severely lodged corn should not be a problem as long as the leaf area remains intact. Premature desiccation could reduce potential yields without giving any benefits. 2,4-D is labeled for pre-harvest weed control. It can be applied after the dough or dent stage. It would effectively control morningglory and sicklepod and help aid corn harvest, but it would not desiccate the corn or increase the dry down speed.
What other cropping alternatives do I have?
Unfortunately, there are few alternatives available at this time of the season. Grain sorghum or tropical corn could probably be planted this late, but yield potential is low and given an early frost these alternatives may result in losing more money than you make. If your crop is a complete loss, investigate disaster benefits and start planning for fall wheat. If your crop has any yield potential at all, then plan on harvesting early and getting what you can.
The Bottom Line
At the time Bertha hit, most of the corn had at least a month to go before reaching physiological maturity. Even developing at a fraction of its normal efficiency, corn grain had the potential to accumulate quite a bit more weight. In fact, potential yields could have been close to those expected before Bertha. Since we were not aware of any other profitable uses for the land between Bertha and corn harvest, we suggested that the majority of the fields should be left and harvested. Farmers shoudld have planned to HARVEST EARLY and to deal with lodged stalks. The Hamby Company, Plainview, TX (phone 806/293-1010)makes a Corn Saver to help get lodged corn into the combine. Neither of us have any experience with it, but a Piedmont grower who bought one to harvest corn damaged by Hurricane Hugo felt it was a good investment. They cost around $4,000 for a 6-row setup, or $5,000 for an 8-row. The company says they plan to be able to get 80-90% of badly lodged corn into the combine. They have sold about 30 units in our area over the last two days. Protect your yield potential and get all you can into the combine.