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Agronomic Crops Network

Ohio State University Extension


C.O.R.N. Newsletter 2013-30

Dates Covered: 
September 10, 2013 - September 17, 2013
Adam Shepard

Harvest Weather Forecast

As discussed last week, the above normal temperature and below normal rainfall pattern would continue and there is no change in that this week.

Overall, expect above normal temperatures and below normal rainfall for the rest of September as discussed last week.

There will be isolated storms until a front passes Thursday. A little more widespread rainfall can be expected with the front late Wednesday into early Thursday. Overall, rainfall will be less than 0.25 inches but isolated totals over 1 inch can be expected if you get under a thunderstorm.

Temperatures will briefly drop to below normal late this week and weekend with highs on Friday in the 60s to around 70!

The climate models continue to hint at some October wetness, but that is no guarantee followed by more dryness as we go into winter and early next spring.

Monthly precipitation predictions for September 2013 - February 2014

We will keep you posted on these winter and spring 2014 trends in the coming weeks and months from the NWS Ohio River Forecast Center.


An old disease makes a return appearance:  Late Season Diseases

An old disease makes a return appearance: Late Season Diseases

Stem canker has been identified in a few fields in Ohio as well as neighboring states this year.  The key symptom is a dieback of the plant.  A canker can be found, for northern stem canker at the 3rd to 4th node.  It is reddish brown and can surround the stem or go up as a streak along one side of the plant.  This can be separated from Phytophthora stem canker as in Phytophthora the base of the plant and roots are decayed while in stem canker the roots and base of the plant are healthy.  Stem canker can be caused by one of two different fungi:  Diaporthe phaseolorum var. caulivora (northern) and Diaporthe phaseolorum var. meridonalis (southern).  Infections by both fungi occur during the vegetative stages during rainy weather, which we had plenty of this year.  Seed infection can also contribute to this disease as well as heavy soybean residue.  Host resistance is the key management strategy and in fact it has been a long time (> 10 years) since we have had fields with reports of high incidence. 

Burndown herbicides for no-tillage wheat

Herbicide options for burndown of existing weeds prior to planting of no-till wheat include glyphosate, Gramoxone, Sharpen, and dicamba.  Dicamba labels have the following restriction on preplant applications – “Allow 10 days between application and planting for each 0.25 lb ai/A used”.  A rate of 0.5 lb ai/A would therefore need to be applied at least 20 days before planting.  We have as usual been receiving questions about the safety and legality of 2,4-D use prior to wheat planting.  We do not know of any 2,4-D product labels that support this use of 2,4-D.  There is some risk of stand reduction and injury to wheat from applications of 2,4-D too close to the time of wheat planting.  Liberty is also not labeled for use as a burndown herbicide in no-till wheat.

The primary targets for a preplant burndown in wheat are the small, emerged winter annual weeds that can overwinter and have a negative effect on wheat the following spring.  This includes marestail (horseweed), chickweed, deadnettle, annual bluegrass, mustards, etc.  Herbicide treatments at this time can also have considerable activity on biennials (wild carrot, wild hemlock), dandelion, and Canada thistle, although herbicides are often more effective on these weeds later in the fall.  The larger summer annual weeds (ragweeds, marestail, foxtails, etc) are going to die after the first hard frost, and soybean harvest decimates these weeds to the point that herbicides won’t be effective on them anyway.  Where wheat is planted into a fallow situation, it may be necessary to target the large summer annuals with herbicide in order to ensure that they do not interfere with planting or wheat stand establishment. 

While glyphosate can adequately control small winter annual weeds, it should be combined with Sharpen or dicamba in fields with a history of marestail problems (or in fields downwind of a neighbor’s marestail nightmare).  A mixture of glyphosate and Sharpen may be the better alternative because of the 10-day waiting period for dicamba.  Sharpen should provide limited residual control of winter annuals that emerge after herbicide application, and the rate can be increased from 1 to 2 oz/A to improve the length of residual.  Gramoxone should also effectively control seedlings of marestail and other winter annuals.  Be sure to use the appropriate adjuvants with any of these, and increase spray volume to 15 to 20 gpa to ensure adequate coverage with Sharpen or Gramoxone.

There are several effective postemergence herbicide treatments for wheat that can be applied in November to control these weeds, in fields where preplant burndown treatments are not used.  The most effective postemergence treatments include Huskie or mixtures of dicamba with Peak, tribenuron (Express etc), or a tribenuron/thifensulfuron premix (Harmony Xtra etc).  We discourage application of 2,4-D to emerged wheat in the fall due to the risk of injury and yield reduction.

Important Wheat Management Guidelines: A 2013 Update

As growers make preparations for planting wheat this fall, we would like to remind them of a few management decisions that are important for a successful crop. Nearly every farm in Ohio has a field or two that could benefit from planting wheat, if for no other reason than to help reduce problems associated with continuous planting of soybeans and corn. Consistent high yields can be achieved by following a few important management guidelines. Listed below are  the most important management decisions that Ohio wheat producers need to make at fall planting time to produce a crop with satisfactory economic returns.

 Variety and Seed Selection. Select high-yielding varieties with high test weight, good straw strength and adequate disease resistance. Do not jeopardize your investment by planting poor quality seeds or by planting anything but the best yielding varieties that also have resistance to the important diseases in your area. Depending on your area of the state, you may need good resistance to powdery mildew, Stagonospora leaf blotch, head scab, and/or leaf rust. Plant healthy, wholesome, clean (remove shriveled kernels), and disease-free seeds, and make sure that the entire seed lot is treated, whether or not the seeds appear to be diseased. In Ohio, seed-borne wheat diseases such as common bunt and loose smut are rarely ever major concerns because growers routinely plant seeds treated with fungicides. Problems with these diseases usually appear in isolated areas where poorly treated, bin run seeds are planted. Seed treatments can play an important role in achieving uniform seedling emergence and giving seedlings a good head start under certain conditions. In addition, the selective use of seed treatments can protect seeds or seedlings from early-season diseases. More information on seed treatments can be found on the field crops disease website:  

Avoid varieties with susceptibility to Fusarium head scab. Unlike foliar diseases that are relatively easy to effectively control with a single foliar fungicide application, fungicide alone will not provide adequate control of head scab and vomitoxin if the variety if highly susceptible. Fungicide application at flowering must be combined with variety resistance to achieve the best results in terms of scab and vomitoxin reduction. Therefore one of the very first, and probably the most important, step in a scab management plan is variety selection. In the past, producers have been reluctant to plant scab resistant varieties because some of the varieties did not yield as well as some of the more susceptible varieties. However, we now have scab resistant varieties with very good yield potential to choose from. A list of these varieties can be found in the 2011 Ohio Wheat Performance Trial (

Rotate wheat with Soybean. Wheat should be planted after soybean not after wheat or corn. Diseases are a big concern in wheat after wheat. One such disease, and by far one of the most important, is head scab. The head scab fungus survives in wheat stubble left in the field after harvest. Wheat planted into this stubble is more likely to have head scab and vomitoxin problem next year, especially if late-spring, early-summer conditions are wet and humid. Our studies have shown that when wheat (or corn) residue is abundant (more spores of the fungus present), only a few days of wet and humid conditions during flowering are needed for head scab to develop and vomitoxin to exceed critical marketing thresholds (2 ppm). For the same reasons, planting wheat after corn is just as bad as planting wheat after wheat. The scab fungus survives equally well in both corn and wheat stubble.

In addition, growers who plant wheat after wheat usually have more problems with diseases such as Cephalosporium stripe and Take-all root rot. Plants severely infected in the fall and winter will become weak and discolored in the spring and often die prematurely without producing grain. In addition, foliar diseases such as Stagonospora leaf blotch, Septoria leaf blotch, powdery mildew, and tan spot become more problematic when wheat follows wheat. These diseases are all caused by fungi that survive in wheat stubble left in the field, and as such, can readily attack the new crop and spread shortly after germination or early in the spring. When diseases become established early, growers are more likely to suffer higher yield and quality losses  

Planting Date. Plant after the Hessian Fly Safe date for your county. The Hessian Fly free dates can be found at ( These dates vary between September 22 for northern counties and October 5 for the southern-most counties. Planting within the first 10 days after the recommended fly-safe date minimizes the risk of serious problems with Hessian Fly.

Hessian Fly-Free Date

This is because on the dates indicated on the map, the weather conditions, especially temperature, are unfavorable for the Hessian fly. As a result, damage caused by this insect will likely be less if wheat is planted after the specific date. However, in Ohio the Hessian fly-safe date is not only about the Hessian fly. Another excellent reason to plant wheat after the fly-safe date is to minimize problems with diseases, especially barley yellow dwarf virus (BYDV). BYDV is transmitted by aphids and tends to be most severe when transmission occurs in the fall. Research has shown that due to unfavorable weather conditions, the aphid population tends to crash after the fly safe date, leading to fewer problems with BYDV. Planting date studies conducted here at OSU a few years ago showed that BYDV problems and yield loss associated with this disease are much higher when wheat is planted well before the fly-safe date. Planting after the fly-safe date also minimizes early establishment of other diseases such as Stagonospora blotch and leaf rust.

Seeding Rate and Planting Depth. Optimum seeding rates are between 1.2 and 1.6 million seeds per acre.  For drills with 7.5 inch row spacing, this is about 18 to 24 seeds per foot of row with normal sized seed. When wheat is planted on time, actual seeding rate has little effect on yield, but high seeding rates (above 30 seeds per foot of row) increase lodging. There is no evidence that more seed is better, it only costs more money. However, as mentioned above, seeding rate should be increased if the crop is planted well after the fly-safe date. Seed size (the number of seeds per pound) and germination rates are critical for determining the proper seeding rate and drill calibrated. That information should be listed on the bag of seed. The table below shows the pounds of seed needed per acre to accomplish various seeding rates using different sizes of seed.

Pounds of Seed Needed to Plant from 1.2 Million to 2.0 Million Seeds Per Acre with Different Size Wheat Seed

Wheat Population Chart

Planting depth is critical for tiller development and winter survival. Plant seed between 1 and 1.5 inches deep and make sure planting depth is uniform across the field. No-till wheat into soybean stubble is ideal, but make sure the soybean residue is uniformly spread over the surface of the ground.  Shallow planting is the main cause of low tiller numbers and poor over-winter survival due to heaving and freezing injury. Planting depth is even more important in late planted wheat. Late planting results in plants that smaller than normal when entering dormancy, with smaller and more shallow root systems than normal, making them more susceptible to heaving next March.

Fertilizer Application. Apply 20 to 30 lb of actual nitrogen per acre at planting to promote fall tiller development. Review your soil test for phosphorus and potash applications. Phosphorus should be applied if soil test levels are below 50 ppm (100 lb/acre) regardless of yield potential. The exact rate will depend on the soil test level and yield potential. Check the Tri-State guide for specific rate recommendations ( The same philosophy would be true for potash. Potash should be applied if soil test potassium levels are below 150 to 175 ppm (300 – 350 lb/acre) regardless of yield potential. For soils with potassium levels below this amount the recommended rate would depend upon the yield potential, soil test level and the cation exchange capacity of the soil, which also may be found at the previous listed website for the Tri-State bulletin. Soil pH should be around 6.5 for optimum production. Secondary nutrients (calcium, magnesium and sulfur) and micronutrients should not be necessary for a fall program on most Ohio soils maintained at the proper soil pH.

The key to a successful wheat crop is adequate and timely management. The above recommendations are guidelines that may be fine-tuned by you to fit your farming operation, soils, and planting conditions. They also assume that you are planting wheat in fields that are adequately drained.

Palmer amaranth update – send lawyers, guns and money, the **** has hit the fan

You may be sick of hearing about Palmer amaranth already but get used to it.  A few things to be aware of right now:

 - There appears to be somewhat of an epicenter of new Palmer amaranth infestations in an area southwest of Columbus, bordered roughly by Midway on the north and Washington CH on the south.  There is a dairy in the area that has been using cottonseed products for feed and a local grower has been transporting these products to the dairy from somewhere in the south.  There are Palmer amaranth plants in a number of fields in the area and also on the grounds of the dairy.  One grower contacted us after finding it in his field, and has since been busy digging out and removing plants.  If you farm in this area, be sure to take some time to scout fields and roadsides now for Palmer amaranth and take appropriate action as necessary.  Palmer amaranth is a prohibited noxious weed in Ohio.

- The Palmer amaranth plants we have found so far do not appear to have formed mature seed yet, which would be indicated by the presence of small black seeds.  We’re not sure why but one hypothesis is that the residual from preemergence herbicides prevented the early flushes of Palmer amaranth, and the later-emerging plants are still reaching maturity.  This means that there is still time to dig up or chop down plants, and ideally also remove them from the field.  Once mature seed has formed, the strategy changes from plant removal to isolation and remediation of infestations.

- The OSU weed science website ( has information on Palmer amaranth, including a short video on identification and a new 11-minute video that explains the risk from this weed.  Similar information can be found on the Purdue weed science website.  If you find plants that you believe to be Palmer amaranth, please contact us to confirm identification, and at that point we can also offer more guidance for management of new infestations.


Reminder to stop and visit the Agronomic Crops Team at the 2013 Farm Science Review


We like to talk about crops, hopefully at this time of year you have a little time to talk back. The Farm Science Review Agronomy demonstration plots are to the east of the exhibit area, on the path from the parking lot to the main pedestrian entrance at Gate C. We’ll be there all day, all three days from 8AM to 5PM. Look for the tent, stop and visit.

2013 highlights

  • Nutrient management – from manure to Phosphorus and Nitrogen placement.
  • Soybean weed control – come talk with us about pigweeds
  • Corn management for high yield – removing the stresses?
  • Sign up for the C.O.R.N. newsletter here, too.

Each day in the Agronomy Demonstration Plots – we will have scheduled speakers at 10AM and 2PM. Here is a link to our schedule: Public Schedule of Talks in the Agronomic Demonstration Plots at FSR

And for Certified Crop Advisers, see all the 2013 FSR CCA College opportunities on the Agronomic Crops Team website:

Visit our new OSU Extension Assistant Director at Farm Science Review

This Farm Science Review will have a new face to help welcome you to the show. Andy Londo is the newest Assistant Director for Agriculture & Natural Resources for OSU Extension and started just this month. He wants to meet producers, supporters and suppliers for production agriculture in Ohio, and this is one great place to do that. In the Assistant Director role, Andy will help shape the education, research and extension activities of the department of Extension. And he is my new boss.

Originally from Michigan, Andy Londo earned his bachelor’s degree in forestry from Michigan Technological University, his master’s degree in forest science from Texas A&M University and his doctorate in forest science from Michigan Technological University. A respected scholar, Londo is known for his research in prescribed fire, forest health, mine reclamation, carbon sequestration, soils, forest management, intensive pine silviculture and non-industrial private forest landowner issues.

Londo has worked as Extension forestry coordinator at Mississippi State University since 2005, where he was responsible for supervising Extension associates, coordinating Extension programing and seeking funding to support programming. He has been a professor of silviculture at the university since 2008.

Andy will be all around the Farm Science Review site – OSU Central will be his office for the show, but he will also be at the Gwynne Conservation area – north up SR 38, in the Small Farms Center, and with us the Agronomic Crops Team out in the Agronomy Demonstration plots at the east end of the exhibit area. Stop Andy wherever you find him and give him your ideas on how best to deliver quality Extension education to Ohio’s producers.

The Farm Science Review is September 17, 18 & 19 at the Molly Caren Educational Center at 135 State Route 38, London Ohio – site of the Farm Science Review. More information is available on the FSR website:

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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.