More Strange Things in Corn

Chad Lee, Extension Agronomist, Plant and Soil Sciences

More strange things are being reported in the corn crop this year. Last week, a producer called to say he was checking ears and the kernels were falling off of the cob. Even stranger, the kernels looked deep, the cob appeared to be of decent quality, but when he pulled back the husks, many of the kernels simply fell off the cob. When these ears hit the snout of the corn head, the kernels simply shattered off of the cob and onto the ground. In a year when high heat and low rains late reduced yield, loosing kernels to the soil is adding insult to injury.

We suspect this to be a late-season stress occurring at or close to blacklayer (physiological maturity). The shattering kernels may be a result of both environment and genetics.

So, if you have seen shattering kernels this year, please send me an email letting me know the name of the hybrid, the field location (nearest town), soil type and as much management information as you know. My email address is cdlee2@uky.edu. Thanks.

Fertilizer Use in Argentina

Note: The following is an update on fertilizer practices in Argentina over the past 20 years. The changes in fertilizer practices over time in Argentina are impacting fertilizer demands in a global fertilizer economy.

Martin Navarro, Graduate Student, Plant and Soil Sciences
John Grove, Agronomic Soil Science, Plant and Soil Sciences

It will soon be spring in Argentina, and fertilizer purchase decisions are being made. Unlike the U.S., where fertilizer use has been a common practice for many years, Argentina’s linear growth in fertilizer use began only 20 years ago (Figure 1). This increased use of fertilizers has been associated with a continued increase in crop yield (Figure 2). It should be noted that the severe drop in fertilizer use in 2008 and 2009 was due to a reduction in the area of corn and wheat,with a corresponding increase in the area of soybean.

Figure 1: Fertilizer consumption in Argentina, from 1990 to 2009.

 
Figure 2: Annual grain (corn, soybean and wheat, averaged together) yield in Argentina, from 1990 to 2009.
 
The nutrients most commonly purchased in Argentina are, in declining importance, nitrogen (N),phosphorus (P), sulfur (S), and potassium (K). Most soils found in the more productive region of Argentina (the Pampas) have high levels of bioavailable P because the soil parent material is rich in this nutrient. The use of S is increasingly common, as deficiencies of this nutrient are being increasingly detected. The soils of the Pampas are richer in bioavailable P, in comparison with soils found in other agricultural regions in Argentina. However, Darwich (1999) has reported significant declines in bioavailable P in these soils, relative to original levels, relative even to levels existing in the early 1980’s.
Despite the large increase in fertilizer use in the past 20 years, nutrient replenishment (replacement of nutrients removed in grain) is still very low and a topic of long-term concern.The fraction of total nutrient uptake that is recycled back to the soil averages about 34%, and replenishment of nutrient stocks with fertilizer averages about 41% for N, 61% for P, 6% for K,and 35% for S. This suggests that these soils will be progressively poorer in their fertility. This problem was also evaluated by Ciampitti and Garcia (2008), for soils of the Pampas region, and they concluded that only 31, 53, 1 and 27 % of the N, P, K and S, respectively, exported by crop harvest was replaced by fertilizer addition.

The situation has been improving with time, though only slightly (Figure 3). Phosphorus and sulfur replacement have made slow but steady progress, in part because fertilizers containing these nutrients are now being more routinely applied to soybean, the crop with the largest production area in Argentina. The Argentine fertilizer industry, as well as various Argentine governmental institutions, expects increased fertilizer consumption and greater nutrient replenishment, especially for nitrogen. This expectation is based on anticipated increases in the production areas of both wheat and maize. In Argentina, these cereal crops are generally better fertilized than soybean. Current wheat and maize production areas are now at their lowest levels in 30 years.

In conclusion, Argentine nutrient management is generally characterized by a negative soil nutrient balance, due to rates of replacement/fertilization that are lower than rates of removal. This has resulted in declines in bioavailable N, P, K, and S levels in Argentine soils. Given this context, appropriate fertilizer rates and sources are important to crop production in Argentina, slowing/preventing nutrient export and depletion of soil fertility. Diagnosis of the fertility needs for a field is based in knowledge of the field’s soil and soil testing is important to that knowledge base. Soil chemical analysis and good nutrient management practices are tools indispensable to sustainable Argentine agriculture.

Figure 3: Nutrient application/removal ratios in Argentina from 1993 to 2007.

References:

Darwich N. 1999. Niveles de P disponible en suelos pampeanos. (Levels of bioavailable P in soils of the Pampas). IDIA 409-412: 1-5. INTA. Buenos Aires, Argentina.

Ciampitti I., F. Garcia. 2008. Fosforo en rotaciones agrícolas de la región pampeana central: II. Balance de P. (Phosphorus in agricultural rotations in the central Pampas region: II. P balance). Actas CD XXI Congreso Argentino de la Ciencia del Suelo. AACS. Potrero de los Funes, San Luis.

Moth Flights of Important Field Crops Pests Increase Dramatically

Fall armyworm moth counts have sky rocketed!

Capture of fall armyworm, Spodoptera frugiperda (J.E. Smith) moths has sky rocketed as indexed by the UK-IPM pheromone baited traps at the UK-REC in Princeton, KY.(Fortunately this does not seem to be the situation in Lexington.) Last week (20 Aug 2010) our capture was a normal, 52 moths/trapweek; today’s count (27 Aug 2010) is 1,038 moths/trapweek! Please view the graphs at: http://www.uky.edu/Ag/IPMPrinceton/counts/fall/fawgraph.htm. Because our trapping network captures the adult moths, we have a heads up on the caterpillar (damaging stage) population that will occur in several weeks. This is the largest capture of FAW in ca. 15 years of trapping and is almost three times larger than the second largest single capture. See more information in Kentucky Pest News of Aug 31, 2010.

Corn earworm (aka soybean podworm) moth flight increases dramatically.

Capture of adult corn earworm (CEW) moths in the UK-IPM pheromone baited traps at Princeton, KY has increased dramatically. The total capture of CEW moths for the week ending 27 August 2010 was 484, up from 82 on Aug 20th. This is the second largest capture of CEW moths in the ca. 18 years of monitoring, with the largest being 525 moths / trapweek in August 2001. This is not as dramatic an increase as we are experiencing with fall armyworm, nevertheless it is pretty unusual. (See: Fall armyworm moth counts have sky rocketed! in Kentucky Pest News 31 Aug 2010).

It is too late in the season for corn earworm to be of any importance on corn, but this pest also feeds on the pods of soybean, especially late maturing varieties. Caterpillars (the damaging stage) resulting from these moths will begin to appear in 1-2 weeks. Those individuals involved in soybean production should scout their fields for the presence of this insect. Corn earworm can be especially damaging because it feeds directly on the pods and seeds. Additionally, it is difficult to scout as it does not feed to any great extent on soybean leaves. One has to get into the plants and look directly at the pods to find this pest.

Kentucky Pest News can be viewed at: http://www.ca.uky.edu/agcollege/plantpathology/extension/kpnindex.htm

Corn stands looking weak from stress

Chad Lee, University of Kentucky

In the the Aug 17, 2010 edition of Kentucky Pest News, Dr. Vincelli warns of aflatoxins and diplodia in corn. Another concern is final stand of the corn crop. Much of the corn crop was under stress from heat and a lack of water. Those conditions usually cause the each plant to pull photosynthate from the stalks and put them in the ear in an attempt to produce seed. While this helps each overcome some yield losses, it also causes stalks to become weak.

As you prepare for this early harvest, check fields for stalk strength and, if possible, harvest weak stands first. The easiest way to check for stand strength is to grab the stalk at about your shoulder height and pull the stalk toward you. Release the stalk and if it returns to its normal upright position, the stalk strength is still good. If the stalk does not return to the upright position, the stalks are weak.

In addition to weak stalks, I have had reports and I have visited some fields where ear attachment to the plant is very weak.  In the worst situations, ears have been found on the ground. . . typically, heavier ears. There may be an interaction between environment and hybrid. So, if you have a field like this, please email me at cdlee2@uky.edu and let me know the hybrid and field conditions. Obviously, such fields need to be harvested sooner rather than later.

Those of you who have farmed for a while know that a summer of stress often brings challenges at harvest. This year appears to be no different.

Wheat planting when futures are high and seed might be short

Chad Lee and Jim Herbek, University of Kentucky

Many producers locked in wheat contracts for 2011 at or over $7 per bushel and some are growing wheat for the first time in five years. There are rumors that seed supply is tight. If these rumors are accurate, there may be some temptation to skimp on seeding rates in order to cover more acres.  If you are one of those producers, just know what your risks are by cutting back and proceed with caution.

Maximum wheat yields normally require a final stand of 30 to 35 plants per square feet, but under the right conditions, stands as low as 20 plants per square foot will yield well. Getting a successful stand requires several things, including timely seeding, an accurate seeding rate, correct seed depth (1.0 to 1.5 inches), adequate soil moisture, and no seedling diseases.

Wheat should be planted from about October 10 to October 30 for most of Kentucky. This window is normally provides the best opportunity for getting a good stand and good growth before the cold winter months. Seed rates can be 30 to 35 seeds per square feet, but if you are considering dropping back a little, this is the time to try it. If planting occurs after October 30, then the seed rate should be 35 to 40 seeds per square foot. These seed rates assume a standard germination of 90%. For seed lots with lower standard germinations, a higher seeding rate is needed.

Drill calibration is absolutely necessary to dropping the correct amount of seeds. This process takes time and should be conducted with each seed lot you receive. If you do not have the time and/or patience for this procedure, then hire someone to calibrate your drill. This procedure will benefit your wheat production system.  Guidelines on calibrating wheat drills is available in the ID:125 Comprehensive Guide to Wheat Management, Chapter 4 “Planting and Drill Calibration” http://www.uky.edu/Ag/GrainCrops/ID125Section4.html.

Adjusting the drill for planting depth also takes time but will result in better stands. These adjustments need to be made in the field on the day of planting. Field conditions change from day to day and the pressure needed to get the desired depth may change day to day as well.

So, if you decide you are short on wheat and you want to skimp on seed, be sure you know the conditions in which you are planting. If possible, try to skimp in situations that will still provide a chance for good stand establishment. In a year when a large part of the 2011 crop may already be sold, skimping on seeding rates should only be used as a last resort.

Wheat in 15-inch rows will work but might cost yield

Chad Lee and Jim Herbek, University of Kentucky

With the increased interest in wheat from futures prices and the anticipated increased acres planted this fall, many farmers are asking if they can use their 15-inch soybean planter to plant wheat. The quick answer is yes, but you might loose some yield.

We have investigated three varieties of wheat at Princeton and Lexington in 15-inch and 7.5-inch rows at Princeton and Lexington for the past two years, giving us four environments. We tested varieties that were known to be prolific, meaning that they produce a lot of tillers. Yields were excellent, ranging from 70 to just over 120 bushels per acre. In two of the environments, there were no differences in yield between 15-inch and 7.5-inch rows. In the other two environments, yields in 15-inch rows were about 8.5% less than yields in 7.5-inch rows.

Based simply on this research, if yields in 15-inch rows are 8.5% less than yields in 7.5-inch rows and futures prices are $7 per bushel, a field of 500 acres will net about $30,000 more with 7.5-inch rows. Trucking and storage have not been included in these returns. However, If we assume the $30,000 over 500 acres, that is a difference of $60 per acre.

So, instead of converting your 15-inch planter to wheat, you might want to consider contracting with someone who has no-till drill and drilling the wheat in 7.5-inch rows. If contracting is not an option and you are not in the market to buy a grain drill, a 15-inch planter can work… it just might yield a little less.  If you do use a 15-inch planter, try to find a variety that produces a lot of tillers.

Check Corn for Pollination and Seed Set

Cory Walters just posted an article about how good prices look right now for corn. In addition, the corn crop looks great from the road. But before you decide to contract that rest of your expected yields, get into the fields and make sure pollination went well.

We have received several reports from county agents of fields with poor pollination. Perhaps the most unsettling report came from Tom Miller, Extension agent in Ballard County, who said that pockets of a field had poor pollination. Plants in the same row had good pollination while others had terrible pollination. (One of his images is attached to this article.) At this point, hot dry weather and slight variations as to when pollen drop occurred appears to be the best explanation. This is unsettling, because the whole field looks excellent from the road.

So, if the silks are dry, then pull back the husks and look at the developing "blisters" or seeds. You know how a good ear of corn should look... even number of rows, pollination from the base to the tip of the ear.

If the silks are still wet, but pollen drop appears to be complete, then you can gently remove the husks and get an estimate of pollination. To do this, make a cut through the husks with a sharp pocket knife along the ear. Start at the base of the ear and slice up to the tip. Make a second slice on the other side of the ear. If you have done a good job making the slices, you should be able to gently pull off the husks without removing the silks. If silks come off with the husks, then get a new ear and start over.

Once you have successfully removed the husks and kept the silks on the ear, hold the ear at the base and gently shake it. You may want to point the top of the ear towards the ground. As you gently shake, silks will fall from the ear if pollination has occurred. Again, you are hoping for all of the silks to fall from the ear. Pollination normally occurs from the base of the ear and then moves toward the top. If you happen to get an ear where the silks near the base fall off, but the silks near the top do not, then pollination may not be complete in the field.