Josh Thompson, Regional Crop IPM Agent, provides a corn yield check at a farm in Jackson County this week. Photo credit: Doug Mayo
Combines began picking through corn last week, and this week the harvesting continues. Jackson County has a corn yield contest that several growers participate in. Having a yield check allows for a friendly competition, but also provides a yield comparison between different fields and hybrid variates.
Test plots of 1.25 acres or larger are harvested, weighed, and analyzed for moisture content at local peanut buying points to determine yields for the competition. Additionally, we can use this information to calibrate yield monitors in the combines. There can be quite a large difference between what the yield monitor says and what the true yield is out in the field.
Check out the video below for some of the activity this week.
Heavy rains in north Florida have had some growers behind in getting ready for the crop season this year. Thankfully, this week has been dry enough for some to do field work. Right now many farmers are plowing land, spraying cover crops, strip tilling, spreading lime, and planting corn, among other things. Unfortunately, projected rains over the coming weekend will probably bring everything to a halt again.
Below are pictures of some of this weeks activity.
Anhydrous ammonia being applied with strip tillage. Anhydrous is a high analysis nitrogen fertilizer but isn’t commonly used in Florida because of our sandy soils. However, it can be very effective on heavier soils like they have here in Campbellton, FL. This grower uses anhydrous for growing corn and cotton. Photo Credit: J. Thompson
More anhydrous and strip tillage. Photo Credit: J. Thompson
Strip tilled corn just starting to come up near Dellwood, FL. Photo Credit: J. Thompson
A good stand of corn near Malone, FL. Photo Credit: J. Thompson
Spraying an oat cover crop with glyphosate to get ready for planting cotton in about a month. Photo Credit: J. Thompson
Local Hi-Cal lime and dolomite mines have been running way behind this year because of the weather. Farm supply dealers have had to wait in long lines to get Hi-Cal and dolomite and some have sourced from other parts of the state. All of this means farmers are paying a higher price this year for lime and may have trouble getting what they need. Credit: J. Thompson
A Closer Look
Thrips are most noticeable, and of greatest concern on corn at two periods during the growing season: on young seedling plants, and at ear formation. On seedling plants their feeding makes the plants look stunted. At ear formation, thrip injury to developing kernels provides entry for infection by Fusarium spp. and subsequent Fusarium ear rot disease.
Some may mistake this late season thrip damage as a disease issue. If you see this type of symptom in your field, contact your county extension agent for a positive diagnosis of thrip injury or foliar disease.
Treatment is usually not necessary on corn seedlings, because plants recover from thrip injury. Thrips are also beneficial at this time because of their role as mite predators. No threshold has been established for damage from thrips at ear formation. Treating for thrips will probably not prevent spread of Fusarium ear rot disease.
Ear Fill Thrip Damage to Corn Leaves
You can see variability across the field.
Lingering cool springtime temperatures have been a pleasure for farmers and fieldworkers, but some local corn fields have not fared as well. Below are a few photos from an irrigated field in the western panhandle which had as much attention a corn field could get.
The producer based his pre-plant fertilizer application on soil test recommendations. Generally, he uses a starter fertilizer, but this year he employed another commercially available product. Dr. David Wright concluded the corn was off to a slow start because the fertilizer was not readily available for corn already having a difficult time in cool, damp ground.
Dr. Wright suggested next year returning to the practice of using a starter fertilizer, but to have faith in this year’s corn. He predicts it will develop normally with continued proper care.
So what is starter fertilizer? Small amounts of nitrogen, phosphorus, sulfur, and micronutrients are often used as a starter fertilizer. The main advantage of starter fertilizer is better early-season growth, earlier dry down, and with many hybrids, higher yield. Corn planted in February, March, or early April is exposed to cool soil temperatures, which may reduce phosphate uptake.
Banding a starter fertilizer two inches to the side and two inches below the seed increases the chances of roots penetrating the fertilizer band and taking up needed nitrogen and phosphorus. Starter fertilizer can also be used in a surface dribble for strip-till planting with the solution applied two inches to the side of the seed furrow for each 20 pounds of nitrogen used.
Currently, the most popular starter fertilizer is ammonium polyphosphate (10-34-0), a liquid. Monoammonium and diammonium phosphates are dry sources and equally effective. There is generally no advantage in using a complete fertilizer (NPK) as a starter, since applying nitrogen and phosphorus is the key to early growth. If soil test levels for P and K are high, a starter with 30 to 40 pounds per acre of nitrogen and 15 pounds per acre of P is adequate for starter application.
Normally, 10 to 15 gallons of a starter fertilizer containing one-third to one-half 10-34-0 and the remainder as 28-0-5 has been effective for early corn growth. Corn will take up around 15 to 20 pounds per acre of N and 5 pounds per acre of P by the time the corn is 15 inches tall. Therefore, high rates of starter P are not necessary unless it is used to supply all of the P for the corn crop in a field requiring the nutrient.
Please see the complete Field Corn Production Guide for more information on fertilization, pest control, and overall management of field corn. The information on pre-plant fertilizer was taken from the EDIS publication, Field Corn Production Guide, written by Drs. David Wright, Jim Marois, Jim Rich, and Richard Sprenkel.
Comparison of a healthy plant to a weaker plant
Northern Corn Leaf Blight lesion. Credit: Jack Price
Rome Ethredge, extension agent in Seminole County Georgia, this week reported incidence of Northern Corn Leaf Blight (NCLB), as did Jake Price in Lowndes County Georgia. This is a fungal disease that can reduce corn yields and is most likley to be found in fields where corn was grown the previous year.
The following information was from taken Rome’s article on Seminole Crop e-News:
Here are some comments from Dr. Bob Kemerait, UGA Extension Plant Pathologist.
1. Jake Price of Valdosta Georgia area found NCLB on some of his earliest corn (March planting date) that is now waist-high… It has been in the field a while.
2. The field is planted corn-behind-corn…. the spores (conidia) are still around from last year…
3. The field is planted to conservation tillage…. not only are the spores (conidia) still hanging around but they are in the crop debris exactly where we left them last year.
4. Rainfall has been abundant… hence greater splash of spores from the debris to the young leaves and also free moisture to aid in the infection process.
5. It has been cool….. the NCLB pathogen rages in temperatures between 64F and 81F…. sound familiar…
In other words.. we seem to have a perfect storm for northern corn leaf blight this year…….
So, what to do?
Question 1. Should every corn grower in the state of Georgia spray their corn at the 5th-to-6th leaf stage with a fungicide?
Answer 1. No, I don’t think that is necessary…. corn in fields with good rotation and where NCLB is not found when the fields are scouted certainly don’t need to be sprayed for this disease now.
Question 2. Well Bob, what fields would you spray early?
Answer 2. From our research, it is clear that IF NCLB is a problem in a field, it is important to apply a fungicide somewhere around the 5th or 6th leaf stage, preferably with a fungicide other than tebuconazole as I think we have better fungicides for this disease. This application is followed by a second application, somewhere around the silking stage. Growers who should consider this application are 1) NCLB is found in the field already, 2) Growers at high risk to NCLB (see description of Jake’s field…) and/or 3) the grower has very high expectations for yield and very low expectations for risk.
Question 3. What if the grower wants to spray early for NCLB but not too early…
Answer 3. In such case, the grower should continue to scout the field and consider risk factors and then decide just before it becomes too late to spray the field with a tractor-mounted-boom-sprayer.
Question 4. What about the early-tassel spray you always talk about?
Answer 4. I continue to encourage all corn growers with any reasonable yield potential to consider making a fungicide application at the early-tassel growth stage for management of southern rust. However, if our crop is disease free, which I doubt, then this application may not be needed.
More information about fungicide treatments for corn as well as general production information can be found in the University of Georgia Corn Production Guide.