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Corn Newsletter : 2018-33
Warm and Wet October ExpectedAuthor(s): Jim Noel
After a very wet September across all but northwest Ohio in the Maumee River basin, we can expect more of the same in October. September saw some locations in the top 5 wettest on record for Ohio like Columbus and Dayton.
We expect the first two weeks of October to average 5-15F above normal with a few days almost 20F above normal. There will be a few days this week with lows of 65-70 degrees which is almost unheard of in October with normal lows in the 40s. The latest low of 70 at Cincinnati is Oct.9 in 1982, since 1947. It is possible to be near that level a few days this week across especially southern Ohio.
Overall, temperatures the first two weeks of October will average 5-15F above normal with the last two weeks 0-4F above normal.
Rainfall will average 1-4 inches the first half of October. The 1 inch will be in southern Ohio and the 4 inches would likely be in the north part of the state. Normal is 1-1.5 inches for two weeks.
See rainfall map above.
Rainfall may relax to more normal with a chance of below normal the second half of the month. The worst of the rain will be in the central and western corn and soybean areas where rainfall of 3-7 inches is possible so harvest delays are possible.
It continues to looks like frost will be no earlier than Oct. 10-20 range which is normal for Ohio but chances are growing it may be more in the Oct. 20-30 range.
Stalk Quality Concerns
Poor stalk quality is being observed and reported in Ohio corn fields. One of the primary causes of this problem is stalk rot. Corn stalk rot, and consequently, lodging, are the results of several different but interrelated factors. The actual disease, stalk rot, is caused by one or more of several fungi capable of colonizing and disintegrating of the inner tissues of the stalk. The most common members of the stalk rot complex are Gibberella zeae, Colletotrichum graminicola, Stenocarpella maydis and members of the genus Fusarium.
The extent to which these fungi infect and cause stalk rot depends on the health of the plant. In general, severely stressed plants (due to foliar diseases, insects, or weather) are more greatly affected by stalk rot than stress-free plants. The stalk rot fungi typically survive in corn residue on the soil surface and invade the base of the corn stalk either directly or through wounds made by corn borers, hail, or mechanical injury. Occasionally, fungal invasion occurs at nodes above ground or behind the leaf sheath. The plant tissue is usually resistant to fungal colonization up to silking, after which the fungus spreads from the roots to the stalks. When diseased stalks are split, the pith is usually discolored and shows signs of disintegration. As the pith disintegrates, it separates from the rind and the stalk becomes a hollow tube-like structure. Destruction of the internal stalk tissue by fungi predisposes the plant to lodging.
Nothing can be done about stalk rots at this stage; however, growers can minimize yield and quality losses associated with lodging by harvesting fields with stalk rot problems as early as possible. Scout fields early for visual symptoms of stalk rot and use the "squeeze test" to assess the potential for lodging. Since stalk rots affect stalk integrity, one or more of the inner nodes can easily be compressed when the stalk is squeezed between the thumb and the forefinger. The "push" test is another way to predict lodging. Push the stalks at the ear level, 6 to 8 inches from the vertical. If the stalk breaks between the ear and the lowest node, stalk rot is usually present. To minimize stalk rot damage, harvest promptly after physiological maturity. Harvest delays will increase the risk of stalk lodging and grain yield losses and slowdown the harvest operation. Since the level of stalk rot varies from field to field and hybrids vary in their stalk strength and susceptibility to stalk rot, each field should be scouted separately.
Premature Sprouting of Corn Kernels
We have received several reports of premature corn kernel sprouting across Ohio. The ear in the picture exhibiting premature sprouting was sampled from one of the Ohio Corn Performance Test plots at the NW Research Station and was associated Trichoderma ear rot. In this particular case, the fungus that causes the ear rot produces compounds that stimulates early germination. However, not all ear rots are commonly associated with premature sprouting. In fact, under the right set of conditions, this phenomenon may occur in perfectly healthy ears, without visual disease symptoms. In addition to ear rots, a combination of other factors, including erect ears, bird damage, and wet weather, may contribute to premature sprouting.
Premature sprouting is most likely to occur when reasonably dry kernels (less than about 20 percent grain moisture content) are re-wetted, especially when temperatures are warm and ear dry-down in an upright position. Rainfall collected by husk leaves on upright ears often leads to kernel sprouting near the butt of the ear. Premature sprouting also occurs when ears are lying on or near the soil surface due to severe stalk breakage or lodging. In such situations, the proximity of ears to moist soil allows a similar re-wetting of the kernels and extensive germination on the cob. The problem is usually limited within fields but if it’s evident across a field it has the potential to cause drying and storage problems.
Ears with sprouted kernels are usually lighter than healthy ears. In some cases, this “lightness” can reduce grain yield and test weight. Sprouted kernels are also more likely to develop molds that are associated with mycotoxins. This could result in price discounts if the problem is extensive. Often, during the harvesting and drying processes, sprouts will disappear, and grain will appear normal. Fields showing widespread sprouting should be prioritized for early harvest. Dry grain at to prevent further growth of the young seedlings and screen the grain prior to storage to reduce the amount of damaged grain and seedling tissue.
For more details on premature kernel sprouting, check out the following articles from Ohio State, Purdue, and Missouri.
Nielsen, Bob. 2012. Premature Corn Kernel Sprouting (aka Vivipary). Corny News Network, Purdue Extension. [online] Available at URL: http://www.kingcorn.org/news/timeless/Vivipary.html
Wiebold, Bill. 2009. Wet Weather Can Cause Seeds to Sprout before Harvest. Integrated Pest & Crop Management Newsletter, Univ of Missouri. http://ipm.missouri.edu/IPCM/2009/11/Wet-Weather-Can-Cause-Seeds-to-Sprout-before-Harvest.
Check Beans for Stink Bug Damage and Plan for Next Year
As farmers progress with soybean harvest we encourage you to take a quick look at your grain quality, especially at field edges. We have been receiving reports of the deformed and discolored beans typical of stink bug damage. If your beans show signs of stink bug damage (or even if they don’t!) consider incorporating stink bug scouting into your management next year, beginning around pod set or early fill. Stink bugs are scoutable and treatable before damage occurs, and we will provide timely information next season in the CORN newsletter on when and how to monitor for this insect in soybeans. A quick guide to Ohio stink bugs and their management can be found here.
Tips for Harvest and Planning for the 2019 Field SeasonAuthor(s): Anne Dorrance
Based on my trip across the state on Saturday, it is clear harvest has started. A couple of things to keep track of as the combines run across the fields:
- Make note of those low yield spots in soybeans to soil sample for soybean cyst nematode levels.
- Did you leave unsprayed strips? Harvest each of these first separately. Yield is not even throughout a field so comparisons to the average of these unsprayed strips are a more accurate measure of what the baseline level of yield is within a field. This is the number to compare yields for any treatments.
- Note: the outside borders of the field are usually not comparable since these have additional secondary factors such as shade from trees, compaction, old fence rows etc. which can impact yield.
- Fields with Sclerotinia should be harvested last. Yes, seed quality will continue to decline but this will avoid contaminating equipment with sclerotia which can then be introduced into more fields. There are limited fields with this pathogen, and this approach will help keep it that way.
- Fields with stink bug injury, generally moldy due to Phomopsis etc.: harvest those ASAP and get the seed dried down. Phomopsis will continue to colonize pods from openings on those pods caused by insect feeding and then colonize the neighboring seeds. This fungus that causes Phomopsis seed decay as well as other seed decay fungi tend to be a bit slow growing. If the seed can be harvested, and dried down it will prevent further growth. It has also been noted that on a seed germination test in the fall, germs will be lower, but the seed where only the outside is colonized, not the germ, the fungus will die under out winter conditions (if the storage is dry) and then the germ will improve over the winter for Phomopsis seed decay.
- While you are also harvesting make note of the varieties that did well on your farms. Not every soybean variety is meant for our wet poorly drained soils. We’ve had lots of reports and observed shallow root systems, extensive root rot, as well as Phytophthora stem rot and sudden death syndrome during 2018. In fields where diseases developed in 2018, pay attention to the resistance on these and other diseases for 2019.
- Remember, every company uses a different rating system, read the fine print to be sure that you understand what resistance actually means for those varieties. Is 1 dead or is it the best?
Are Cover Crops for You? Podcast AvailableAuthor(s): Alan Sundermeier, CCA
This podcast is a series of short interviews with farmers and specialists and solving problems on the farm and how cover crops can be a part of the solutions.
Episodes include discussion on issues including managing herbicide resistant weeds, improving soil health by reducing compaction and erosion, improving soil organic matter and water holding capacity, and cover crops as a forage. This is a podcast for farmers who may be considering using cover crops and are looking to solve problems on the farm. Episodes focus on practical on-farm solutions and include a variety of different farmers across the Midwest as guest speakers.
See an overview of episodes, and listen to the podcast for free online at: http://mccc.msu.edu/podcast-cover-crops/.
About the C.O.R.N. Newsletter
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.
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.
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