C.O.R.N. Newsletter 2013-37

Dates Covered: 
October 29, 2013 - November 5, 2013
Editor: 
Curtis Young

Stalk Rot and Lodging Problems in Corn

Wind damage early in the season coupled with delayed harvest and rain late in the season have some producers concerned about stalk rot and lodging problems in corn.  When stalk rot occurs late in the season as it often does, it may have little or no direct effect on yield.  However, stalk lodging, which results from stalk rot, can have such a significant impact on harvest losses that it is often considered to be the one of the most significant yield limiting disease of corn.

Several factors may contribute to stalk rot and lodging, including extreme weather conditions, insects and diseases, and these may occur very early in the season.  However, most hybrids do not begin to show stalk rot symptoms until shortly before physiological maturity.  It is difficult to distinguish between stalk rots caused by different fungi because two or more fungi may be involved.  Similarly, certain insects such as European corn borer often act in concert with fungal pathogens to cause stalk rot.  Although a number of different fungal pathogens cause stalk rots, the three most important in Ohio are Gibberella, Collectotrichum (anthracnose), and Fusarium.  For more information on stalk rot in corn, consult the OSU Plant Pathology web site "Ohio Field Crop Diseases" (http://www.oardc.ohio-state.edu/ohiofieldcropdisease/) for more details and pictures of the disease symptoms associated with these pathogens.

The presence of stalk rots in corn may not always result in stalk lodging, especially if the affected crop is harvest promptly.  It's not uncommon to walk corn fields where nearly every plant is upright yet nearly every plant is also showing stalk rot symptoms!  Many hybrids have excellent rind strength, which contributes to plant standability even when the internal plant tissue has rotted or started to rot.  However, strong rinds will not prevent lodging if harvest is delayed and the crop is subjected to weathering, e.g. strong winds and heavy rains.

A symptom common to all stalk rots is the deterioration of the inner stalk tissues so that one or more of the inner nodes can easily be compressed when squeezing the stalk between thumb and finger.  It is possible by using this "squeeze test" to assess potential lodging if harvesting is not done promptly.  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 slow the harvest operation.

Collecting Yield and Identifying Problem Spots

Soybean harvest is wrapping up and some fields beat all expectations and some indicate potential problem spots in the field.  As you think back to those questionable spots where the seed chatter through the combine got kind of quiet or you are scanning the yield monitor results - you have the best data for those low yield pockets.  This year there could be several reasons, part due to the weather and part due to biotic factors like soybean cyst nematode. 

Heavy rains that occurred shortly after planting affected stand in some parts of the state, while we did not have as much replanting as we have had in recent years - stands were an issue in some of the more poorly drained fields.  Flooding, were the seed is submerged for more than 3 days - kills plants.  Secondly, saturated soils for 24 - 48 hours give ample time for the water molds to attack soybean plants.  We saw several cases this summer, especially when varieties with low levels of partial resistance to P. sojae were planted.  For flooding damage, it is time to revisit the drainage on that farm.  For thin stands - it is time to focus more on the partial resistance (field resistance) for management of Phytophthora root and stem rot part of the variety package.  Go back and see what seed treatment was used on that seed, and check the rate of the metalaxyl/mefenoxam portion of the seed treatment package.

SCN is here and is reaching some very high levels in some fields.  In my own research plots - the trouble symptoms are plants that are half the height than the rest of the field and these cases were 2/3 the yield of the rest of the study.  In other studies, we have no above ground symptoms and have less than half the yield.  From my two SCN colleagues here, Dr. Terry Niblack and Dr. Chris Taylor, they are picking up populations of SCN that can reproduce on the line PI 88788 which is the source of resistance in most of the soybean varieties.  So - the first question is when was the last time you sampled that field? If it is greater than 10 - it is probably time to do a check.  The second question, how many years out of 5 have you planted soybeans?  If it is 4 - it is really time to check.  The third question for yield, did your field yield 10 - 15 bushels below the county/state yield/performance trial averages?  It is really time to check. 

Having pulled soil cores in Ohio soils before, it can be a back breaking task.  So with the rain this week - since you will have a break from harvest - this week may provide an opportunity.  Fall is the best, but I expect from all the corn that is still out there, there are some fields that soil sampling is just not going to happen until the spring.  The SCN is not going to go anywhere, with a hard winter the eggs that sit outside the cyst may get killed, which is why we have said fall is best. 

There are numerous labs, including our own C.Wayne Ellett Plant Diagnostic Clinic and they are all listed on our fact sheet:  http://ohioline.osu.edu/ac-fact/pdf/0039.pdf.

Availability of Sulfur from Fall Applied Gypsum

Recently a producer asked if he applied gypsum this fall or any other sulfur source would it be available for next year's corn crop?

Gypsum is calcium sulfate and the sulfate will respond in the soil environment similar to nitrate.  It will move with water and most likely will have moved away by the time a corn crop is planted next spring.  Thus, like fall applied nitrate-N, I would not expect it to be available for a future crop.  However, it may be utilized by a fall planted crop.  This would be true for any sulfur fertilizer in the sulfate form.  On the other hand, elemental sulfur is in a chemical form that would take time to convert to sulfate.  Sulfur must be in the sulfate form to be taken up by plant roots.  Fall applied elemental sulfur should convert to sulfate by corn planting time.  The conversion of elemental sulfur to sulfate will release hydrogen ions, which will have an acidifying effect on the soil.  Sulfate form of sulfur does not have an acidifying effect alone but when combine with ammonium, the hydrogen ions release by the conversion of ammonium to nitrate will gradually lower soil pH.  Thus elemental sulfur is often used to lower soil pH but not sulfate.

Software for Nutrient Management Plan Development Workshops

Using an example farm, this workshop will walk through the steps to create a Nutrient Management Plan as required for EQUIP and other conservation programs offered by NRCS.  Software demonstrated is focused on MapWindows GIS for MMP, a geographic information software front end and MMP software used to plan crop rotations needs for nutrient recommendation, site analysis, and fertilizer allocation.  The plans developed cover the agronomic needs of the crops while considering soils, slopes and other site characteristics which may need attention to minimize off site movement.

Individuals who wish to become Technical Service Providers (TSP) with NRCS to provide CAP 104 Nutrient Management Plans will walk through a CAP 104 plan development.  Participants will also find the workshop serves as an important background to develop a CAP 102 Comprehensive Nutrient Management Plans for livestock producers.  TSP payment rates for the development of these plans can be found on the NRCS site at: http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1049335.pdf

Workshop participants are asked to bring a laptop computer to use for the plan demonstration.  A hanby workbook walk through the plan development step by step is included in materials provided.  More details on MapWindows GIS for MMP and MMP software as well as links to download the programs can be found at http://www.purdue.edu/agsoftware/mmp/

The 2013-2014 Workshop will be offered:

Date

Location

Address

11/14/2013 

Ohio State University Extension-Putnam County

1206 East Second St, Ottawa , OH

12/10/2013 

Ohio State University Extension- Marion County

222 W Center St., Marion, OH

1/14/2014

Ohio State University Extension-Putnam County

1206 East Second St, Ottawa , OH

2/6/2014 

Ohio State University Extension-Fayette County

1415 US Rt 22 SW, Washington Courthouse, OH

2/27/2014 

Ohio State University Extension- Marion County

222 W Center St., Marion, OH

More detail on the workshop and the day's agenda can be found at https://agcrops.osu.edu/calendar.  Preregistration is request 1 week prior to the event at http://surveys.cfaes.ohio-state.edu/cfaes/index.php/974228/lang-en.  For other question contact Greg LaBarge at labarge.1@osu.edu or 419-460-0600.

2014 Ohio Commercial Pesticide Applicator Recertification Conferences

The 2014 Ohio Commercial Pesticide Applicator Recertification Conferences have been set and announced by the Ohio Pesticide Safety Education Program of OSU Extension (http://pested.osu.edu).  The dates and locations of the conferences are January 30, 2014 - Dayton Convention Center; January 31, 2014 - Sandusky, Kalahari Conference Center; February 19, 2014 - Akron, John S. Knight Center; and March 6, 2014 - Columbus Convention Center. 

For driving directions, the agenda for each day, pre-registration fees, on-site registration fees, a list of categories offered, and on-line registration link or a download link for a printable registration form visit the above website of the Pesticide Safety Education Program.  Remember that one needs to attend the entire day to meet the five hours required for an Ohio commercial license.  Plan ahead and register early to avoid missing these convenient opportunities to acquire recertification all in one day.

Reciprocity is available for licensed commercial pesticide applicators who hold licenses in Indiana, Kentucky, Michigan, Pennsylvania and West Virginia.  To determine the amount of credit for each state, please visit the website or call the individual state's licensing agency.

The Ohio Pesticide Safety Education Program provides training, education, and outreach to pesticide applicators about the safe, proper, and legal use of pesticides.  The program works with farmers, businesses, and public agencies to protect human health and the environment and serves as a critical part of job training and business growth in Ohio.

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About the C.O.R.N. Newsletter

C.O.R.N. is a summary of crop observations, related information, and appropriate recommendations for Ohio Crop Producers and Industry. C.O.R.N. is produced by the Ohio State University Extension Agronomy Team, State Specialists at The Ohio State University and Ohio Agricultural Research and Development Center. C.O.R.N. Questions are directed to State Specialists, Extension Associates, and Agents associated with Ohio State University Extension and the Ohio Agricultural Research and Development Center at The Ohio State University.