Corn Drydown in the Field

The cool, cloudy and wet weather has not helped with drydown of corn in Kentucky. We have been fielding (pun intended) many questions about how much longer to let the corn stand versus getting it out of the field.

An excellent article, Field Drydown of Mature Corn Grain was just updated on this very subject by Bob Nielsen at Purdue.

Dr. Nielsen says:

"Simply put, warmer temperatures and lower humidity encourage rapid field drying of corn grain."

Also:"Average daily drydown rates will range from about 0.8 percentage point per day for grain that nears maturity in late August to about 0.4 percentage point per day for grain that nears maturity in mid- to late September... "

If the weather is cool, cloudy and/or wet, there may be very little to no drydown. So, in a normal year, you might expect corn grain to dry down by 5.6 percentage points in a week. For this season, with the current weather, expecting corn to dry down by 2 percentage points in one week could be optomistic. For what it's worth, the 10-day forecast for much of Kentucky calls for rain in four of ten days.

If corn has reached 25% grain moisture, the risks with leaving corn in the field with the current weather conditions are: 1) increased chances for sprouting in the ear, 2) increased chances for Diplodia, etc. to spread on infected ears, 3) increased chances for ear loss from wind, 4) increased chances for lodging, and 5) increased chances for another rainstorm to come in and do more damage.

The negatives of harvesting corn grain wet (between 25 and 16%) are: 1) increased demand and wear on drying equipment, 2) increased drying costs, 3) increased dockage if sold directly off the farm, 4) increased weight per bushel of grain for hauling (i.e. more hauling costs), and 5) increased chance for spoilage if dryers are not working properly.

In addition to these negatives, soil compaction is at a greater risk in some of these fields. Soil is most susceptible to compaction when the soil is just a little too wet to plant (ie. just below field capacity). Conditions favorable for field-drying of corn are also favorable for drying soil.

If we knew exactly what the weather forecast was for the next two weeks, we all could make some really smart decisions. Aside from an accurate weather forecast, I would suggest trying to get into fields between the wet weather. If possible, target fields that are drier and/or fields at greater risk for lodging. Also, if you haven't done so already, make sure your drying equipment is working at its best.

We have some very large yields currently in the fields across the state. Hopefully, we can get most of that into the bins.

Bt Corn Refuge Requirement Confusion

Ric Bessin, Entomology

There may be considerable confusion regarding refuge requirements in 2010 for Bt corn. In the past in Kentucky all we need to understand was that the minimum refuge size needed to 20% of the total corn acreage. If there was a Bt toxin to control corn rootworm, then the refuge needed to be within the same field or immediately adjacent to the Bt field. Immediately adjacent to means that a fence, ditch, or road is all that separates the refuge from the Bt field. Bt corn that only had toxins to control corn borers and other Lepidoptera must have the refuge within ½ mile, but a ¼ is preferred.

This has become a bit more complicated with the approval of SmartStax corn. The minimum refuge size for SmartStax is different, it is only 5% of total corn acrage (in cotton producing areas it increases to 20%). Where the possible confusion lies is that the refuge size for all other Bt corn technologies stays the same, only the SmartStax will have the reduced refuge size of 5%. The table below outlines the refuge requirements for the various Bt technologies on the market, corn grown in Kentucky would use the corn belt minimum refuge sizes. The reason why there is a reduced refuge with SmartStax is that we use multiple independent toxins to control the key insect pests. This is a new strategy for resistance management that the other Bt technologies don’t have.

Order of details:
Product Name, Min. Refuge (Corn Belt), Min. Refuge (Cotton Areas), Proximity to Bt Field

YieldGard CB, 20%, 50%, Within 1/4 to 1/2 mile
YieldGard RW, 20%, 20%, Within or adjacent to
YieldGard Plus, 20%, 50%, Within or adjacent to
YieldGard VT, 20%, 20%, Within or adjacent to
YieldGard VT3, 20%, 50%, Within or adjacent to
YieldGard VT3 Pro, 20%, 20% Within or adjacent to
SmartStax, 5%, 20%, Within or adjacent to
Herculex I, 20%, 50%, Within 1/4 to 1/2 mile
Herculex RW, 20%, 20%, Within or adjacent to
Herculex Xtra, 20%, 50%, Within or adjacent to
Agrisure CB, 20%, 50%, Within 1/4 to 1/2 mile
Agrisure RW, 20%, 20%, Within or adjacent to
Agrisure CB/RW, 20%, 50%, Within or adjacent to


There are two other types of Bt corn that are still in the regulatory process with approvals pending. This includes AcreMax and Viptera. These again may have different refuge requirements, particularly the AcreMax.


While the reason for planting a refuge is to maintain a population of Bt- susceptible corn borers, growers should still manage those refuges to avoid serious losses. When using a 20 or 5 % (Smartstax only) refuge with Bt corn plantings, growers may consider spraying for corn borers if scouting indicates it is an economic problem.

Storing Diplodia Ear Rot-Affected Corn

Paul Vincelli, Plant Pathology

Diplodia ear rot (DER) is being reported rather widely this year. Questions have arisen about storage of DER-affected corn. The fungus that causes DER won’t develop further if moisture content is below the normal target of 15.5%. However, rotted kernels are damaged kernels, and since the grain integrity is compromised, other fungi more tolerant of low moisture will have an easier time growing. Our agricultural engineers recommend drying damaged corn an extra 0.5 to 1.0 point of moisture for better storability and cooling it as quickly as possible. Producers should make sure to keep that grain well aerated and dry, and market it sooner rather than later.

Fortunately, there are no known mycotoxins produced by the strains of the DER fungus found in North America. In addition to several recent Kentucky Pest News articles on this subject, more information on this disease is available in a UK Extension publication available at http://www.ca.uky.edu/agc/pubs/ppa/ppa43/ppa43.pdf.

Stalk Strength Reminder

Paul Vincelli, Plant Pathology

Corn fields in the many areas that experienced wet, overcast, soggy weather since the last issue of Kentucky Pest News for the most part remain unharvested. Weather conditions generally, and the widespread occurrence of southern corn rust, conspire to make this a season with increased risk for stalk rots.

Be sure to scout fields for stalk strength. Scouting will help you select fields for harvest based on how strong the stalks are. Harvest those with the weakest stalks first, before they blow down from a strong gust.

The easiest way to check for lodging potential is to walk through the field and, at about chest height, push the plants about 8-12 inches from vertical. A stalk that bends and fails to spring back is prone to lodging. If 10-15% of the stalks in a field exhibit lodging potential, the field should be scheduled for early harvest.

Soybean Maturity and Fall Freeze Dates

Dr. Don Hershman released a Soybean Rust Spray Advisory for the western half of Kentucky (I-65 and west) this morning. If soybeans are at R4 (full pod) to R5 (beginning seed) then they are at risk of losing yield from soybean rust. Soybeans at R4 or R5 are also at risk to lose yield from another factor - freeze.

The median first freeze dates (32 degrees Farhenheit) for most of western Kentucky are near October 22 (about 30 days from this posting). Of course, October 22 is an average, meaning that the first freeze date can occur before or after the average. In one out of 10 years, the earliest freeze date is around October 6 (about 15 days from this posting). On the other side of the spectrum, the earliest frost freeze date can occur as late as around November 6 (about 45 days from this posting).

Generally, soybeans in Kentucky require about 30 days for seed fill (R6 growth stage). So, soybeans currently at R5 would require about 35 days to reach physiological maturity. The cool, cloudy weather might delay maturity a couple of days.

So, if you are considering spraying a fungicide to prevent yield losses from soybean rust, also consider your chances for a freeze event.

Soybean Rust Update and Spray Advisory for Selected Fields

NOTE: This SBR update is directed to KENTUCKY SOYBEAN PRODUCERS. If you live in another state, read what I say, below, with the extreme sensitivity that what I am writing may not (and probably does not) apply to you. I encourage you to find out what is being said by the Extension Plant Pathologist your state by going to www.sbrusa.net.

On Friday of last week we found soybean rust in Ballard County in far west KY. The level of disease was as low as it could possibly be (one leaf out of 100 that had one lesion, with one pustule!). This was the third SBR find in KY, the other two finds being in Warren County and Henderson County.

I have been pretty open about my belief that the vast majority of soybeans in Kentucky are well beyond the point where they could possibly be damaged by soybean rust. However, I also know that some fields in the state were planted very late and that development in July may have been hindered by wet and cool conditions. The bottom line is that there may be the rare field that needs all of October to completely fill pods. When I say, rare field, I am talking about fields planted in July to a group 5 soybean. By way of comparison, our Grains Crop Specialist, Dr. Jim Herbek is conducting a planting date study here at the UKREC where he planted a mid-group 4 variety on July 7th. That field was at the beginning flowering stage (R1) on August 10 and currently is at the full seed (R6) stage. The fields I am referring too would probably be at the full pod (R4) stage or barely into beginning seed (R5) at the present time.

My guess is that we could have considerable soybean rust in west Kentucky by the middle of October. By then, most soybean fields in the state will be at the R6 stage or later, and some will have been harvested. But, I am aware of the possibility that a few soybean fields may still be filling pods during the second part of October (assuming we do not have a hard frost before then). So, while most of you will not be impacted, if you have a field that may still be filling pods by mid-October, it would be wise to consider the prospect of applying a triazole fungicide (like Folicur or a generic, all of which are fairly inexpensive) soon if a highly specific set of conditions exist.

If you believe you have fields that may still be filling pods the last two weeks of October, please contact your local county Extension office. I have given them a soybean rust "Yield Loss Calculator", developed by UK's Dr. Saratha Kumudini, that will help you decide if spraying is to your economic advantage or not.

This advisory applies to the area west of I-65. If you are east of I-65, I would say you are “good to go” for 2009.

Soybean Aphid Remain Active, Mexican Bean Beetle Appears

I continue to receive reports of Soybean Aphid (SA) populations at or near threshold level. In Addition, there are larger populations being reported but on more mature beans. Those interested in soybean production are reminded that historically SA populations reach their greatest size in September. This is not new. What may be different in 2009 is a larger proportion of later planted soybeans (due to a rainy spring) which results in more numerous soybean plants maturing to the R6 stage later in the year. Simply put this places more fields at greater risk than we normally see. It may also be the case in 2009 that SA populations are larger in size because we have experienced a cooler summer. In many KY summers, temperatures over 90 F predominate. These higher temperatures reduce the population growth rate.

Regardless of the reason, soybean plants less mature than R6 will remain at risk of SA populations. There are still fields of soybeans at the R4 stage (seems unbelievable, doesn’t it?!), which will take several weeks to mature to R6.

The threshold remains the same 250 aphids / plant, on 80% of plants with an increasing population. In addition this threshold accounts only for the aphid damage on the plants. As KY producers most always plant narrow row soybeans you will need to consider the losses associated with running down your beans. A very rough guess is about 9%, but this depends upon your row width,the width of the tires on your spray rig and the width of each pass (boom width).

On a final note; a population of Mexican bean beetle (MBB) has been reported from Pickett Co. TN. This is a TN/KY border county just south of the Kentucky Co.’s of Cumberland & Clinton. It has been many years since we have seen problems with MBB in KY, but it may be worth a look in the eastern region of our soybean production area. My thanks to Mr. Richard Daniel, Extension Agent,Pickett County, TN. for the photo of the MBB damage.




MBB Damaged plants

Harvest Wet and Dry the Grain

Harvest corn wet and plan to dry it in the bin. The delayed maturity, cooler temperatures and wet weather will make field-drying very difficult this season. In addition, ears are heavy (a good thing) but waiting a long time for field-drying increases the chances for those heavy ears to pull stalks over. The wet conditions also provide a favorable envrionment for stalk rots and progession of ear diseases. With all of these things going against field-drying, the better option is to plan to harvest the corn wet.

Corn harvest can begin when grain moisture approaches 25 percent. Corn grain should be dried to market moistures (usually 15.5% for field corn and 14.0 % for food grade corn) or to 13 percent if corn will be stored throughout the summer.

For excellent resources on grain bins, drying grain, storing grain, etc. visit the University of Kentucky Grain Storage website operated by Dr. Sam McNeill.

The Price of Food

We will not use this site for opinions on a regular basis. However, the issue addressed herein seems to be picking up steam, and I thought it was time to venture away from "planting dates and seeding rates" and respond to the issue. The following are the opinions of Chad Lee and not necessarily those of the University of Kentucky or the Cooperative Extension Service. We will get back to "planting dates and seeding rates" in future postings.

Is a highly efficient agriculture and cheap food necessarily a bad thing? A recent article by Brian Walsh for Time Magazine (Getting Real about the High price of Food, Aug. 21, 2009) suggests that it is and that our cheap food is an illusion and is really costing much, much more. This is the latest in a series of articles, books and films questioning modern agriculture and its methods.

Mr. Walsh ties pork production to pigs grown in extreme confinement, doped on antibiotics and fed with cheap corn grown with “millions of tons of chemical fertilizer.” The events of pork production are grossly distorted. To describe pork production that way is akin to suggesting that mountains of forests were clear-cut, tons of timber were milled and barrels of poisonous ink were used to print the very magazine in which the article appears.

Both statements above have a shade of the truth, but the truth is heavily draped in exaggeration and fear. The argument strikes at emotions, first, by telling people that they should be afraid of their food and then speckles in a few facts, distorted as they are, as an attempt to appeal to logic. The double-pronged approach is extremely effective.

The very tone of the article is indicative of people who worry very little about having enough to eat, a luxury not shared by many people around the world. In some ways, U.S. farmers and agriculture are victims of their own successes. In the United States, we now have the smallest percentage of the population producing the largest supply of food ever. By having a very small proportion of the people producing food, a very large proportion are free to pursue other interests, develop new technologies, advance new policies and to even become journalists.

As people move away from the farm and lose their connection with their distant ancestors, they tend to romanticize agriculture. Farming is often depicted as a “simpler lifestyle” as many urban dwellers remember summer visits to grandparents or cousins in the country. Memories of the old family farm mingle with songs like “Old McDonald’s Farm”, and television shows like “Little House on the Prairie” where all the animals live peacefully together in a single barn and the family spends more time singing or playing than actually working.

The reality is that agriculture always has been challenging. If it were not so, more people would live and work on the farm. Agriculture is inherently risky. It requires huge investments up front with only the potential for profits several months to years away. A drought or a flood or an outbreak of disease or insects can destroy crops and months of hard labor and investment. The goal of farmers, ranchers and researchers is to improve efficiency, quality and consistency of the food supply and the facts demonstrate our shared success. The result is a food supply that is the cheaper, safer and more abundant than ever . . . and unfortunately an urban population completely disconnected from the realities and challenges of agriculture.

This disconnection is clearly on display with what Mr. Walsh deems an acceptable farm. Mr. Walsh decries the modern large farms as being “factory farms” because they sell large quantities of cattle or crops. His alternative is Niman Ranch, which markets large amounts of “all-natural” beef, pork and poultry from many farms, has its own CEO and was founded by a former attorney for Earthjustice. So, Mr. Walsh complains about a modern feedlot operation who buys cattle from many smaller farmers across the country, finishes those cattle, and then sells those cattle at a price that is affordable by most households in the U.S. However, Mr. Walsh favors a farm corporation with a CEO who markets and sells cattle for many farms at a price that only the wealthy can afford. Bashing the large family farm in favor of another large corporation with projected 2008 revenues of $75million (according to Wikipeda) seems highly illogical.

Mr. Walsh says that the recent recalls and outbreaks are examples of a dangerous food supply that is getting more dangerous. The recalls are examples that the regulatory agencies are doing their jobs. Food contamination is as old as agriculture, itself . . . actually, it probably predates agriculture when people first killed animals and didn’t fully cook the meat, or when they used unsanitary methods to handle and consume fruits and vegetables. Mr. Walsh would likely suggest that we didn’t have recalls 100 years ago. He’s right. No one was checking; people just got sick and died!

Mr. Walsh says that farmers are eroding soils with modern agriculture. Erosion has and still does occur in the United States. In fact, erosion has always been a challenge in agriculture. The U.S. farmer in conjunction with researchers at Land Grant universities and the USDA Agricultural Research Service have worked very diligently over the last 100 years to develop production techniques that greatly reduced erosion. By comparison, the largest loss of soil from erosion from farming occurred in ancient Africa with primitive farming techniques. Mr. Walsh praises today’s ‘organic farmer’ as being sustainable. The irony is that organic farming uses practices very similar to those used by ancient Africans as they destroyed their soil resources.

The disconnect between those who consume food and those who produce it likely will widen as agriculture continues to improve production practices. Many modern farms are large farms, and many large farms are family farms. These family farms are intent on producing food safely, efficiently and sustainably. They think long term and are planning to pass on the farm and its natural resources to the next generation. The American consumer should thank the American farmer for producing such a safe, abundant and relatively inexpensive food supply…and for not having to produce it themselves.

The disconnect between people consuming food and the efforts of producing it are fertile ground for seeds of fear and distrust. Those of us who work in Cooperative Extension at Land Grant Universities constantly field questions from well-intentioned citizens who are genuinely concerned about their food. They are not exactly sure where and how their food is produced. Those who adamantly despise modern agriculture, or perhaps the consumption of animal proteins, are prolific at writing and communicating. They are very effective at delivering their message. Those engaged in producing food are much better at …well, at producing food. In general, we are great at talking shop with our counterparts, but we are terrible about explaining to our neighbors what we do. Those of us remaining in agriculture must defend the successes of modern farming.

The opinions of Chad Lee were expressed above and not necessarily those of the University of Kentucky or the Cooperative Extension Service.

Soybean Aphid & Other Insects in Double-Crop Soybeans

I have received several reports and questions from Extension agents, consultants and company reps concerning near economic threshold populations of Soybean Aphid (SA). Fortunately, all of these fields so far are in R6 or later stages. However, in addition a number of these reports included the observation that there are many other fields that are still in the R3 to R5 stages. These earlier stage plants will remain at risk to SA until they reach the R6 growth stage. These are the fields in which you should spend your scouting time.

The SA economic threshold is 250 aphids per plant, on 80% of the plants, with an increasing population. This threshold holds through plant stage R5. For more mature plants a great many more aphids per plant would be required to provide a benefit for an insecticide application. The exact number is currently under investigation but it is likely at least 500 aphids per plant and may well be 1000 aphids per plant.

In addition there have been scattered questions concerning stinkbugs and bean leaf beetles. Both of these insects are still present and will be feeding directly on the pods. At least one report I have seen, contains stinkbug numbers much greater than the threshold and bean leaf beetle populations very near thresholds. Both of these insects bear close observation as beans progress to maturity.

Yield Contests for Corn and Soybean

The corn and soybean yield contest forms are now available online at the Grain Crops Extension website and the Kentucky Yield Contest Site.

Both of these contests are opereated through the University of Kentucky Cooperative Extension Service and funded by the Kentucky Corn Growers Association, the Kentucky Soybean Board and agricultural industry.

Rules and guidelines are very similar to the 2008 contest. For the 2009 contest, we are asking for soil series (Huntington, Crider, Pembroke, etc.).

The National Corn Growers Association also has the NCGA Corn Contest, which has state and national winners. The rules and regulations are more restrictive than the Kentucky Corn Yield Contest. A farmer may submit a copy of the NCGA entry form to the Kentucky Yield Contest.

For more information about these contests, please contact your extension agent.