As I think about where we are in corn production in Georgia, I realize that we have corn anywhere from a V9 stage to just emerging in middle to north Georgia. I looked back to information that I shared with you over the years, and realized that not a lot has not changed when it comes to the corn crop as a whole in April. This time of the year on the farm is always busy with planting, managing crops, getting supplies, moving tractors from field to field, troubleshooting problems, fixing equipment. Yes…..the list goes on and on. So, you certainly get the picture. There is much to do but little time to do it, right? IF you planted over a month ago or just recently and your crop is just emerging, please take the time to take a few minutes to walk the fields and assess your successes and failures. I wrote about this a couple of years ago, and it’s good to always review what we’ve done to make sure we are not making mistakes that are or were preventable. Keeping good records on your success and mistakes will pay dividends in your future. Remember in corn, it is very important to keep records in growing degree days rather than calendar days. Temperature and light are the driving factors in our crops, particularly in corn, and it can tell you much more about how to manage corn successfully.
A few weeks ago, the southeast went through a couple of days of near freezing temperatures in the southern portions of the state to below freezing in the upper counties of the state. Fortunately, little corn was planted in areas that reach below freezing for a few hours. Most of the damage overall to the crop was cosmetic but stressful. On some of the older corn, you had burn and twisting of leaves in the whorl and some replant situations. In younger corn, the temperatures were cold enough to burn most of the leaf tissue. Fortunately, the weather after the cold snap has been good and supported rapid growth. Over the last several days, the growing degree units are averaging ~20 to 25 gdu’s per day in the southern areas of the state, which means corn will add about 1 leaf every three+ days. Be careful, it is very easy to get behind in side-dressing the crop with nitrogen and soil moisture. Rainy conditions in some areas have helped us avoid irrigating the crop for a time.
I encourage all to take time to walk your corn fields and look closely. Whether your corn is just emerging or at a V-7 to V9 stage, taking the time to review the state of the crop is quite important. Check your spacing, plant emergence, stage of growth. Ask yourself these questions: “Am I a happy with the results so far? “Could I have done better? “Why are these plants much smaller than the rest?” Pull it up and look at it. Go deeper with your questions. “Was the seed deeper or shallower than the others?” “Has an insect fed on it?” “Did my starter fertilizer pump quit?” “Am I satisfied with my spray program?” Or, “Do I have a lot of weeds emerging?’ “Is my crop at the right stage to sidedress?” You can only become a “student of the crop” if you get out and truly study it. Determine the problems or challenges now! Don’t let them linger if you can do something about it and if you can’t, make sure to note when, where, what, why, and how it happened so that you can avoid it next year. Problem solving is what you do to make it better next time. Our mistakes sometimes create stress and lead to yield loss. Now is a good time to assess what you have done well and what hasn’t gone the way you wanted it. IF you are just beginning to plant, make sure to review last year’s problems and mistakes and work at getting it right this time.
Dr. Bob Kemerait, UGA plant pathologist, is very good about helping us avoid certain mistakes that cost you dollars prior to planting. Unfortunately, it easy to see where we fail to know that we may have had a nematode problem. Corn fields where the crop is V2-V4 and severely stunted could be caused by a number of factors, but nematodes are a major possibility. He recently provided an update on what he was seeing in some of our corn fields. I encourage you to sample for nematodes- especially stubby-root, sting, and southern root-knot.” If you see uneven growth in your corn fields, check the roots of good plants vs poor plants and look for root pruning from nematodes. Recognize the problem now so that it can be solved NEXT year. If you are uncertain, call your local county extension agent for help in identifying the signs of root pruning or any other problems that you might find. I hope you don’t have this problem.
If you see your fields beginning to show signs that your burn-down and pre-emerge herbicide program is diminishing and the crop is at a V3 to V4 stage, then a post-emergent program is very important to conduct now. With our warming day time temperatures, corn will move rapidly and it can use assistance to keep well ahead of troublesome weeds.
Another important management practice to review is the proper timing of your nitrogen applications. Generally speaking, the V4-V6 stage are the critical growth stages to having enough nitrogen on corn to ensure that nitrogen isn’t a limiting factor in the early ear development phase. The amount of nitrogen topdressed during this time depends on your management plans and what the environment has been since you planted. If you have less than 50 to 75 lbs N per acre available going into the transition phase (between vegetative and reproductive), I suggest starting your topdressing by V4 and no later than V5. Having a greater amount of N available earlier allows you a little more time to apply your topdressing but not much. It is important to be finished by V6-V7 if you cannot inject nitrogen through your pivot and have to finish all of your N applications by ground equipment.
If you have irrigation, injecting N through the pivot is the most efficient and effective method of applying nitrogen in corn. Dribbling nitrogen (both liquid or dry) by the row is the next preferred method as it keeps the majority of N closet to the root system early in the growth phase and ear development phase. Broadcasting N is an efficient application but may not be the most effective as some N will be captured in the whorls of leaves causing some burning of tissue. It will require rainfall or irrigation to get that which does fall into the whorls dissolved in solution and ultimately in soil solution by washing off the plant and onto the soil. In addition, nitrogen in the middle of the row is far enough away that it takes time for roots to reach the area where the nitrogen is available.
The general nitrogen recommendation ranges from 1 to 1.2 lbs of nitrogen for every bushel in your yield goal depending on your soil type. If you believe your farm and management style has the capacity to produce 250 bushels per acre then it would take 300+ lbs of N per acre. Yes, corn is and can be more efficient and produce a bushel for every 1.0 pound or less of nitrogen per acre however in sandier, coarse soils with low CEC, it is better to error on the high side. If you have the capability to apply N though your pivot, divide your total N supply into increments and apply every 10 to 14 days, finishing up at tassel.
I always encourage growers to conduct tissue analysis throughout the life of the crop. It is hard to manage the nutrient status of the corn plant efficiently without studying the uptake and content over time. Consistent analyses help you see the use and uptake of what you have applied. If you see a nutrient beginning to decline, you can be proactive in adding only what is needed to protect the yield from any nutrient stress that will cause loss.
One last thought… If you have a crop growing in some fields and you’re waiting to get another crop in the field (such as cotton or peanuts), at least take the time to walk and look. It may add some time of reflection, of a job well done and the potential for a great year. Take a deep breath and release the stress of urgency. If you see some problems that can be solved, then make a note and get it done. You caught it in time.
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