C.O.R.N. Newsletter: 2014-36

  1. Harvest Delays Impact Corn Performance

    According to the USDA/NASS ( http://www.nass.usda.gov/ ) as of Sunday, Oct. 19, 23% of Ohio’s corn was mature, compared to 30% for last year and 32% for the five-year average.  Persistent rains have delayed corn harvest across the state and are not helping with field drying.  Many growers are delaying harvest until grain moisture drops further.  However, leaving corn to dry in the field exposes a crop to unfavorable weather conditions, as well as wildlife damage.  A crop with weak plant integrity is more vulnerable to yield losses from stalk lodging and ear drop when weathering conditions occur.  The widespread root lodging that occurred as a result of wind storms in July is contributing to this problem.  Additional losses may occur when ear rots reduce grain quality and can lead to significant dockage when the grain is marketed.  Some ear rots produce mycotoxins, which may cause major health problems if fed to livestock.

    Several years ago we conducted a study that evaluated effects of four plant populations (24,000, 30,000, 36,000, and 42,000 plants/A) and three harvest dates (early-mid Oct., Nov. and Dec.) on the agronomic performance of four hybrids differing in maturity and stalk quality.  The study was conducted at three locations in NW, NE, and SW Ohio over a three year period for a total of eight experiments.  Results of this study provide some insight on yield losses and changes in grain moisture and stalk quality associated with delaying harvest.  The following lists some of the major findings from this research.

     

    KEY FINDINGS

    * Results showed that nearly 90% of the yield loss associated with delayed corn harvest occurred when delays extended beyond mid-November.

    * Grain moisture decreased nearly 6% between harvest dates in Oct. and Nov. delaying harvest after early to mid Nov. achieved almost no additional grain drying.

    * Higher plant populations resulted in increased grain yields when harvest occurred in early to mid-October.  Only when harvest was delayed until mid-November or later did yields decline at plant populations above 30,000/acre.

    * Hybrids with lower stalk strength ratings exhibited greater stalk rot, lodging and yield loss when harvest was delayed.  Early harvest of these hybrids eliminated this effect.

    * The greatest increase in stalk rot incidence came between harvest dates in October and November.  In contrast, stalk lodging increased most after early-mid November.

    * Harvest delays had little or no effect on grain quality characteristics such as oil, protein, starch, and kernel breakage.

    In this study, yields averaged across experiments, populations and hybrids, decreased about 13% between the Oct. and Dec. harvest dates.  Most of the yield loss, about 11%, occurred after the early-mid Nov. harvest date.  In three of the eight experiments, yield losses between Oct. and Dec. harvest dates ranged from 21 - 24%. In the other five experiments, yield losses ranged from 5 - 12%.

    Grain moisture content showed a decrease from the Oct. to Nov. harvest dates but little or no change beyond the Nov. harvest dates.  Grain moisture, averaged across experiments, hybrid, and plant population, decreased 6.3% points between the Oct. and Dec. harvest dates, with most of the decrease occurring between the Oct. and Nov. harvest dates (5.8 % points); only a 0.5 % point decrease occurred after early-mid Nov.  Population effects on grain moisture content were not consistent.  Differences in grain moisture were evident among hybrids on the first harvest date in early-mid Oct. but were generally negligible on the later dates.

    A Field Loss Calculator for Field Drying Corn

    Agronomists at the University of Wisconsin have developed a “Field Loss Calculator” Excel spreadsheet available at: ( http://corn.agronomy.wisc.edu/Season/DSS.aspx ) that allows producers to calculate the costs of harvesting today versus allowing the crop to stand in the field and harvesting later.  The spreadsheet accounts for higher drying costs versus grain losses during field drying.  It allows the user to account for elevator discounts and grain shrink.

  2. Potential for Corn Ear Rot and Mycotoxin Problems in Ohio

    Author(s): Pierce Paul

    It is already the third week of October and most of the corn is still standing in the field.  Some of the earlier-planted fields are being harvested, but at relatively high moisture levels.  This is causing some concern among producers as to the potential for ear rot and mycotoxin problems.  In fact, we have already received several samples of moldy ears from some fields, but so far the problem does not seem to be widespread, with only a few fields affected.  Moreover, not every ear rot is associated with vomitoxin or other mycotoxin contamination of the grain.  However, ear rots could potentially become more of a problem if it continues to rain and the corn remains in the field for an extended period.   

    One of the very first steps to determining whether you will have a problem with vomitoxin or other mycotoxins is to know which ear rot you have in your field.  Generally, it is fairly easy to tell ear rots apart based on the color of the fungal growth on the ear, where the moldy kernels are located, and how they are distributed on the ear.  Other good indicators are the prevailing weather conditions and susceptibility of the hybrids.  For the two most common ear rots in Ohio, Gibberella and Diplodia, both of these diseases develop best when wet weather conditions occur during the first few weeks after silking, with Gibberella being favored by slightly cooler temperatures than Diplodia.  For both diseases, spores of the fungus are splashed onto the silk where they penetrate and grow into the ear.  However, infection may also occur at the base of the ear, especially if it rains late in the season and the ears remain in an upright position, collecting water at the base between the husks and the kernels.

    Diplodia causes a thick grayish-white mass of mold to grow on the ear, usually beginning from the base and growing toward the tip.  With Gibberella, a visible white to pink mold usually covering the tip or more of the ears is characteristic of this disease.  The Gibberella ear rot fungus produces mycotoxins that are harmful to animals.  These include deoxynivalenol (Vomitoxin) and zearalenone and T-2 toxin, all of which may cause health problems in livestock.  Therefore, suspect grain should be tested for these mycotoxins by chemical analysis before being fed to animals.  As a general rule, do not feed any grain with 5% or more Gibberella moldy kernels.  Hogs and young animals are particularly sensitive to these mycotoxins.  Diplodia ear rot is less of a concern from a mycotoxin standpoint, but animals do refuse to eat grain with high levels of Diplodia-damaged kernels.  Additionally, severely affected grain has low nutritional value.

    Certain hybrids are more susceptible to one or more ear rots than others.  Examine ears to determine the presence of ear molds.  Make a note of which ear rots are present and hybrids that are most affected.  Make future hybrid choices based on this information.  Growers are advised to follow certain harvest and storage guidelines to minimize problems associated with kernel rots and mycotoxin contamination:

    1. Harvest at the correct moisture and adjust harvest equipment to minimize damage to kernels.  Mold and mycotoxins tend to be higher in (machine or insect) damaged kernels.

    2. Dry harvested grain to 15% moisture and below to prevent further mold development in storage.

    3. Store dried grain at cool temperatures (36 - 44F) in clean, dry bins.  Moderate to high temperatures are favorable for fungal growth and toxin production.

    4. Periodically check grain for mold, insects, and temperature.

    5. If mold is found, send a grain sample for a mycotoxin analysis to determine if toxins are present and at what level.  For more on moldy grain, mycotoxins, and mycotoxins sampling and analysis visit the following websites: ( http://ohioline.osu.edu/ac-fact/pdf/0052.pdf ).

  3. More on Fall Herbicides with Regard to the Enlist System

    Author(s): Mark Loux

    The USEPA last week issued approval for Enlist Duo, the glyphosate-2,4-D premix for use in the Enlist corn and soybean system, in six states, including Ohio.  The approval came with a number of conditions that set a new precedent really, and we will cover these in more detail later this fall.  Dow informed us that they would provide more information in the near future about intentions for the scope of the 2015 launch of Enlist.  They are still working on export clearances for some countries and as with most new things, availability will be limited initially anyway.  We obviously have problems with herbicide resistance in Ohio, which have reduced the utility of some herbicide sites of action.  So new weed management technology is needed and beneficial, and this includes the Enlist system along with the traits that provide resistance in soybeans to dicamba and group 27 herbicides (HPPD inhibitors - mesotrione and isoxaflutole).  All of these have a fit somewhere to help manage current herbicide resistance problems, and they all have the potential to cause new herbicide resistance problems if not properly managed.  There is already resistance to 2,4-D and dicamba in annual weed species, and it’s pretty much a no-brainer to say that we expect to have weed populations resistant to these herbicides in Ohio at some point based on the coming potential for intensive use in oversimplified herbicide programs.  Dow and Monsanto have primarily mentioned the need for residual herbicides in these systems to help prevent resistance, which gets us about 50% there (maybe).  There is a bigger issue of how technologies are rotated over a period of several years, and whether we end up treating the current herbicide-resistant weeds too often with 2,4-D or dicamba within and over years because it’s easy and effective (at first). 

    Case in point - management of marestail in soybeans with 2,4-D.  One of the trends in marestail control programs has been inadequate control of marestail with a spring glyphosate/2,4-D burndown, especially when applied too late in spring and/or in the absence of a fall herbicide treatment.  Lack of fall treatment results in overwintered marestail that are large and old and more difficult to control, whereas the fall treatment results in a spring burndown situation consisting mainly of a low density of young, small spring-emerging plants.  Including other burndown herbicides with the glyphosate/2,4-D may or may not solve this problem.  Experience with the Enlist system indicates that even without a fall herbicide treatment, multiple in-season applications of 2,4-D (burndown followed by POST) seem to control marestail well.  Doing so will probably result in the development of resistance to 2,4-D in marestail, though, since this is the type of approach that led to glyphosate resistance - multiple applications of the same herbicide for control of the same weed.  In this case, including residual herbicides with the preplant burndown herbicides certainly helps control the marestail that can emerge after planting, but doesn’t help with control of the plants that were already present when the burndown was applied.  The 2,4-D has to pull the load completely on these, so the risk of resistance is not mitigated unless a more comprehensive approach is used.  Bottom line - fall herbicide treatments remain a key component of marestail management programs, even where Enlist soybeans will be planted next spring.

    The majority of our crop areas are still largely weed-free at the end of the season, with another 10 - 20% that has substantial problems with one or more weeds.  So it’s obvious that many growers in Ohio have managed current herbicide-resistant crop technology and herbicides well, and made changes as needed to stop further infestations of resistant weeds.  A similar approach will be necessary with new technology, because it remains to be seen whether companies have the incentive or ability to adequately steward their own products.  Recent history doesn’t leave us with a lot of optimism about this, and growers should expect that the approach they ultimately take would likely have to be more aggressive and smarter than the one promoted by providers of new technology.

  4. EPA Finds No Benefit with Neonicotinoid Seed Treatments

    Seedcorn maggot damage that reduced soybean stand
    Author(s): Andy Michel

    Last week, the EPA determined that there is no benefit from neonicotinoid seed treatments on soybean.  There complete ruling can be read here (http://www2.epa.gov/sites/production/files/2014-10/documents/benefits_of_neonicotinoid_seed_treatments_to_soybean_production_2.pdf ), and is based on an analysis of data published comparing treated and non-treated soybean.  They conclude that “Published data indicate that in most cases there is no difference in soybean yield when soybean seed was treated with neonicotinoids versus not receiving any insect control treatment.”  Furthermore, they find that the seed treatments only last during the first 3 - 4 weeks after planting, which does not overlap with activity of the more important soybean pests.

    EPA’s decision is also consistent with what we see in Ohio.  There are three main pests to monitor during the first 3-4 weeks after planting.  One pest is slugs, which are not insects and are not affected by insecticidal seed treatments.  Two is bean leaf leaf beetle, which can cause defoliation of emerging soybean.  However, severe defoliation which decreases yield is rare (often the plant can grow out of it), and we have good foliar applications which are very effective in extreme cases.  The third pest is seedcorn maggot.  As the picture shows, this can be an important pest.  However, seedcorn maggots are only a major concern when a green cover crop (like alfalfa) is tilled under and planting occurs 5 - 8 days later (Indeed, the picture was a special case from one of our trials where we purposefully timed it right for seedcorn maggot infestation.  If we had waited 2 - 3 days more to plant, it is likely that we would not have seen any damage). 

    It is important to note that this is not an outright ban of insecticidal seed treatments on soybean.  Rather, it should be a reminder of the need to carefully use these tools in an integrated pest management manner and to encourage safe, and profitable, soybean production.  This is especially critical since the big driver for EPA's report could be due to the harmful effects of neonicotinoids on honey bees and other beneficial insects.  However, soybean seed treatments have never really been under much suspicion for causing bee kills.  There is far greater concern about the effects of corn seed treatments on bees, since there are several, well-documented cases of honey bees being killed during corn planting.  Until an official ruling on neonicotinoid seed treatments on corn, growers are urged to use caution next spring during corn planting to avoid bee kills.  We will be sure to add updates to this important issue over the winter.

  5. 2014 Corn, Soybean, Wheat and Alfalfa Field Guide Available for Fall Evaluations

    With late crop development this year, we still have a lot of crops to check.  One excellent tool is the Corn, Soybean, Wheat and Alfalfa Field Guide - updated and in a new format this year - will help with this chore.  The Field Guide is available for sale on OSU Extension’s eStore, or may be ordered from any county Extension office as well.

    This link will take you to the store for the hard copy: ( http://estore.osu-extension.org/productdetails.cfm?PC=2845 ); the price is $12.50.  Many use their droid, iPhone or iPad in the field for that there is a digital version available now too: (http://estore.osu-extension.org/productdetails.cfm?PC=2841 ), for $10.00.

    Reasons to buy the Field Guide now:

    - ear rots

    - stalk rots

    - soybean seed molds

    - insect identification (for those that are moving into your house)

    - updated fertility recommendations

    - weed identification

    - yield estimates

    and so much more.

Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.

Contributors

Amanda Douridas (Educator, Agriculture and Natural Resources)
Eric Richer, CCA (Educator, Agriculture and Natural Resources)
Glen Arnold, CCA (Field Specialist, Manure Nutrient Management )
Greg LaBarge, CPAg/CCA (Field Specialist, Agronomic Systems)
Les Ober, CCA (Educator, Agriculture and Natural Resources)
Mark Badertscher (Educator, Agriculture and Natural Resources)
Mike Gastier, CCA (Educator, Agriculture and Natural Resources)
Nathan Douridas, CCA (Farm Science Review Farm Manager)

Disclaimer

The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.

CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.