C.O.R.N. Newsletter: 2015-19
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Prospects for “Muddied Corn”
During the past two weeks, flooding and ponding have occurred across Ohio, especially in river bottoms and along streams. In some localized areas, this may have resulted in partial and complete immersion of corn in nearby fields, especially in low spots. When water drains off these fields, plants may be covered to varying degrees with a layer of mud. Will corn plants covered by a layer of mud survive and can it perform normally? The layers of silty mud covering plants will limit or prevent leaf photosynthesis. Bacteria deposited in leaf whorls by flooding can result in disease and kill plants. On the positive side, most corn in Ohio was at a stage of growth less vulnerable to flood damage when it occurred. Corn planted before mid-May was well beyond V6 (the six leaf collar stage) when the growing point is at or above the soil surface and less sensitive to flooding and associated anaerobic soil conditions. If the duration of flooding was brief, limited to several hours, and temperatures were moderate, damage should be minimal. Moreover, if corn was subjected to flooding at mid-vegetative stages of development, most leaves on affected plants should not be severely impacted by the mud coatings (assuming that mud in the whorl does not inhibit normal emergence of subsequent leaves). Corn plants produce up to 21 leaves, so at V10, about half the corn leaves have yet to emerge from the whorl. The leaves that have yet to emerge are the most important for the corn plant because the upper canopy produces most of the corn plant’s yield potential. According to the National Crop Insurance Service’s defoliation charts, complete leaf loss at about V10 results in 28% yield loss. However, it’s unlikely that the photosynthetic capacity of leaves has been completely destroyed in plants covered with mud. Rain forecast later this week will wash silt off leaves allowing for resumption of photosynthesis. It will also help wash mud out of leaf whorls allowing new leaves to emerge.
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NEW! Soybean and Small Grain Website (stepupsoy.osu.edu)
The soybean and small grain production lab has gone digital. For information on research results, news, and upcoming events in the soybean and small grain lab visitstepupsoy.osu.edu. You’ll also see the faces of technicians, graduate students, and undergraduates in the soybean and small grain production lab. (They are the ones behind all research efforts!)
You can also follow us on Twitter @stepupsoy to see what is going on in the field.
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Late Harvest and Grain Quality Concerns
Wheat harvest will likely be late again this year. Physiologically, the crop is now ready for harvest in some fields, but will likely not be harvested until the first or second week of July or even later. Late harvest coupled with excessive rainfall mean more time for late-season mold growth, mycotoxin accumulation, test weight reduction, and sprouting, all of which collectively could result in poor overall grain quality.
Test weight (grain weight per unit volume or grain density) is one of the grain quality traits most likely to be affected by harvest delay and wet conditions. Low test weights usually occur if grain is prevented from filling completely or maturing and drying naturally in the field. Rewetting of grain in the field after maturity but prior to harvest is one of the main causes of reduced test weight. When grain is rewetted, the germination process begins, causing photosynthates (i.e., starch) to be digested. This leaves small voids inside the grain which decreases test weight. Additionally, grain will swell each time it is rewetted and may not return to its original size as it dries which will also reduce test weight. Thus the enlarge kernels will take more space but weigh the same, allowing fewer kernels to pack in the measuring container, lowering the test weight.
Rain and harvest delay may also lead to pre-harvest sprouting in some varieties. Sprouting is characterized by the swelling of kernels, splitting of seed coats, and germination of seeds (emergence of roots and shoots) within the wheat heads. Some varieties are more tolerant to sprouting than other, and for a given variety, sprouting may vary from one field to another depending on the duration of warm, wet conditions. Sprouting affects grain quality (test weight). Once moisture is taken up by mature grain, stored reserves (sugars especially) are converted and used up for germination, which leads to reduced test weights. Even before visual signs of sprouting are evident, sugars are converted and grain quality is reduced. Since varieties differ in their ability to take up water, their drying rate, the rate at which sugars are used up, and embryo dormancy (resistance to germination), grain quality reduction will vary from one variety to another.
In addition to sprouting, the growth of mold is another problem that may result from rain-related harvest delay. To fungi, mature wheat heads are nothing more than dead plant tissue ready to be colonized. Under warm, wet conditions, saprophytic fungi (and even fungi known to cause diseases such as wheat scab) readily colonize wheat heads, resulting in a dark moldy cast being formed over the heads and straw. This problem is particularly severe on lodged wheat. In general, the growth of blackish saprophytic molds on the surface of the grain usually does not affect the grain. However, the growth of pathogens, usually whitish or pinkish mold, could result in low test weights and poor overall grain quality. In particular, in those fields with head scab, vomitoxin may build-up to higher levels in the grain, leading to further grain quality reduction and dockage. While vomitoxin contamination is generally higher in fields with high levels of wheat scab, it is not uncommon to find above 2 ppm vomitoxin in late-harvested fields that have been exposed to excessive moisture. Even in the absence of visual scab symptoms, the fungi that produce vomitoxin may still colonize grain and produce toxins if harvest is delayed.
To minimize grain quality losses, it is best to harvest wheat on the first dry-down. Harvesting at a slightly higher moisture level (18% for example) may also be useful for minimizing quality losses, particularly those associated sprouting and mold growth due to rainfall and harvest delay. However, if grain is harvested at moisture above 15%, it should be dried down below 15% before storage to minimize mold growth and mycotoxins in storage.
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Northern Corn Leaf Blight: Earlier than Usual this Year
We are already seeing Northern Corn Leaf Blight (NCLB) in some Ohio corn fields. Why are we seeing NCLB this early and how will this affect our yields? For this disease to develop this early, three basic conditions must be satisfied: 1) the fungus (Exserohilum turcicum) must be present; 2) the hybrid planted must be very susceptible to the prevalent races of the fungus; 3) and environmental conditions must be highly favorable.
In fields with early NCLB, the symptoms are very characteristic of a susceptible reaction to the disease, with one-to-six inch long cigar-shaped gray-green to tan-colored lesions on the leaves. This suggests that those fields were indeed planted with susceptible hybrids. Since NCLB develops best at temperatures between 66 and 80 F, accompanied by extended periods of wetness, recent moderate temperatures and frequent rainfall have certainly favored infection and disease development. In addition, the NCLB fungus is always present because it survives in crop residue in the field, and this season the spore load is likely much higher since we had fairly high levels of the disease towards the end of last season. In fact several of the affected fields are no-till, with corn planted into or next to fields with corn stubble.This may be the perfect storm. Spore build-up + susceptible hybrid + extended periods of favorable weather conditions usually = major disease problems.So, unless, the weather becomes unfavorable over the next few weeks, this disease will continue to spread in fields planted with susceptible hybrids and will likely damage the upper leaves well before grain fill is complete. This would lead to substantial yield loss. When NCLB become established before silking, losses may be as high as 50% if favorable conditions persist. Continue to monitor the progress of the disease and the weather over the next 7 to 10 days and be prepared to treat susceptible fields with a fungicide in order to prevent the disease from spreading to the early leaf and leaves above the ear.
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July OSU Agronomy Field Days
Weed Day
The 2015 OSU Weed Science Field Day hosted by Mark Loux will be held on Wednesday July 8 at the OARDC Western Ag Research Station. Registration starts at 8:30 and a field tour with presentations by OSU faculty, staff and students will start at 9 am. There is also, as usual, the opportunity to view studies of interest on your own.
The cost is $30, which includes the tour book and lunch. Please RSVP to Bruce Ackley,Ackley.19@osu.edu, and include the number of people in your group. Payment can be via cash or check the day of the event. Address of the research station – 7721 South Charleston Pike, South Charleston, OH. Location – about 7 miles south of I-70 from South Vienna on SR 54, or about 4 miles from the Springfield side of I-71 on SR 41. For more information see the OSU Weeds blog: https://u.osu.edu/osuweeds/.
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Western Agronomy Day
The Western ARS Agronomy Field Day will be held July 15, with registration at 8:30AM until 9, then end the day at 3PM. The farm is located at 7721 South Charleston Pike (SR 41), South Charleston, Ohio. The Western Agricultural Research Station is the University research center for agronomy in western Ohio. This site carries a significant load of work on soils and conditions that closely resemble much of western Ohio cropping systems. Join us to learn how to improve conditions on your farm.
The field day begins with morning in-field sessions from 9:00 a.m. until 12:00 p.m. This will feature three 1-hour talks and visits in the field at the researcher’s plots. Speakers include Plant pathologist Anne Dorrance, Agricultural engineer John Fulton, and Soybean & Small grains agronomist Laura Lindsey.
Lunch will be served at noon in the Western Ag Research Station’s air-conditioned conference room. You will have time to visit and ask the specialists for their opinion of crop expectations.
For the afternoon we will provide a wagon tour of other projects on the station. We will make four one-half hour stops with Soil fertility specialist Steve Culman, Agronomist Alex Lindsey, Entomologists Andy Michel & Ron Hammond and Corn specialist Peter Thomison.
Pre-registration is requested by July 10th, the cost for the day is $20 per person payable at the door and includes lunch. Contact Harold Watters Extension Field Specialist at 937-599-4227, watters.35@osu.edu or Joe Davlin Western farm manager at 937-462-8016, davlin.1@osu.edu to register.
We thank the Ohio Soybean Council for their support of the Western Agronomy Field Day. CCA continuing education credits have been approved for 5 hours of Crop Management. See you on July 15th. Visit our website for more information about the farm: http://www.oardc.ohio-state.edu/branches/branchinfo.asp?id=9.
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Northwest Agronomy Day
The Northwest Agricultural Research Station 4240 Range Line Road, Custar, OH will hold it annual Field Crops Day on Thursday, July 30 from 9 – 11:30 A.M.
The Program will include presentations and opportunity for discussions on:
• Management of Soil Borne Diseases in Ohio
• Results of Nine Year P and K Fertilization Study
• Drought Tolerant Corn Hybrids: What Is the Fit for Northwest Ohio
• Methods to Test for and Agronomic Practices to Improve Soil Quality
Pesticide and CCA continuing education credits will be available. The Custar Ohio Station is 2.5 miles northeast of Hoytville at the corner of Oil Center and Range Line roads in Wood County. For more information contact farm manager Matt Davis at 419-257-2060, davis.1095@osu.edu or see the station website: www.oardc.ohio-state.edu/branches/branchinfo.asp?id=3.
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June Sets Rainfall Records for Many Parts of Ohio
June will go down as forecast with it being a wetter and warmer than normal month. Most of the warmth came from moisture and clouds holding overnight lows being held up where daytime temperatures were close to normal.
The outlook for July is for continued wetness for the first half of the month followed by drying in the second half. Temperatures will start cooler than normal but will turn back warmer than normal in the second half of July.
Rain chances will continue daily or every other day into the first week of July.
El Nino continues to grow in the equatorial Pacific Ocean and will likely persist into 2016. Research by the National Weather Service Ohio River Forecast and Ohio State University shows Ohio crops yields are impacted negatively during El Nino years especially to corn and wheat with the risk of below trend-line yields.Further information on impacts of El Nino to the Ohio Valley can be found here:
http://www.erh.noaa.gov/ohrfc/lanina.htmlThe latest 16-day rainfall forecasts continue to indicate 100-200 percent of normal rainfall in Ohio the next two weeks. http://www.erh.noaa.gov/ohrfc/HAS/images/NAEFS16day.pdf
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.
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