C.O.R.N. Newsletter 2012-38

Dates Covered: 
November 6, 2012 - November 20, 2012
Editor: 
David Dugan

Late-Harvested Corn and Ear Molds

Ear molds are always a concern in late-harvested corn, especially if the harvest delay is due to excessively wet conditions as is the case this year. This is of particular concern in areas that were affected by the drought during the summer and had problems with aflatoxin, since delaying harvest may also increase aflatoxin contamination. However, aflatoxin is not your only concern when harvest is delayed. Stalk, root, and ear rots may also cause considerable damage in fields waiting to be harvested. Root and stalk rots leave plants weak and highly vulnerable to lodging, while ear rots may lead to grain contamination with mycotoxins. Deoxynivalenol (vomitoxin), zearalenone and fumonisin, as well as aflatoxins are all examples of toxins produced in moldy ears. However, not all ear molds are associated with mycotoxin contamination. Some opportunistic fungi grow on the husk without affecting the grain. These typically leave the ear looking dark and discolored, but when the husk is removed, the grain looks healthy and normal. The only way to tell whether moldy-looking ears are actually contaminated with mycotoxins is to exam the ears and send samples to a lab for testing. 

Storage Guidelines for Ear Rot-Affected Corn: 1) Adjust harvest equipment to minimize damage to kernels. Mold and mycotoxins tend to be higher in (machine or insect) damaged kernels; 2) Dry and store harvested grain to below 15% moisture to minimize further mold development and toxin contamination in storage; 3) Store dried grain at cool temperatures (36 to 44°F) 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 mold identification and analysis to determine if toxins are present and at what level; 6) Clean bins and storage units between grain lots to reduce cross-contamination.

How much fertilizer does it take to move soil test levels?

Phosphorous and potassium exist naturally in the soil as a part of rock, clay and other minerals that make up soils. Levels of phosphorous in the soil can be between 100 to 3000 pounds of total P per acre. Potassium exists in higher quantities of 10,000 to 50,000 pounds of total K per acre. These levels are substantial but plant available P and K are the important measure in crop production. Due to the buffering of the soil solution quantities of nutrient from these sources along with the associated fixation and release with fertilizer addition or crop removal does not affect soil test level on a 1:1 basis.

The buildup formulas for P and K fertilization found in the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa give us some indication of the amount of fertilizer needed to change soil test levels 1 ppm for both P and K. This concept plays a role in what we need to do when we have a year like 2012 where drought substantially reduces yield, or where we have high soil test levels due to past practices, and want to know how long until we would draw down to maintenance limits.

The buildup equations in the Tri-states indicate that it takes 20 lbs./A of P2O5 to change soil test P levels one ppm. For potassium the equations indicates 6 to 10 lbs./A of K2O are required to change soil test 1 ppm depending upon the soil CEC.

Just to use phosphorous as an example a 150 bushel/acre corn crop will remove 55 pounds of P2O5/acre in the harvested grain. Thus the 150 bushel corn crop would move soil test level approximately 3 ppm.

A new Factsheet, Interpreting a Soil Test Report AGF-514-12, can be found at http://ohioline.osu.edu/agf-fact/pdf/Interpreting_a_Soil_Test_Report_AGF-514-12.pdf . This will help you understand the various factors found on a soil test report and how they relate to soil fertility needs for a crop.

 

2013 Agronomy Workshop – Feb 19 and 20

Mark your calendars; the 2013 OARDC Agronomy Workshop/In-service is scheduled for next February in the Fisher Auditorium, on the Wooster Campus of OSU. This 2-day program will run from 9:30 a.m. until 3:00 p.m. on February 19 and 20, will feature presentations and hands-on activities on a range of important crop production, pathology, entomology, and weed science issues facing the field crops industry. Topics ranging from Disease, Insect and Weed Resistance in Population to Interpretation of Statistics in Field Research will be covered, as well as updates on disease, insect, weed, and mycotoxin detection and management. The content of this program will meet the needs of both our new county Extension Educators as well as more seasoned Educators, Field Specialists, and Crop Consultants, and will be team-taught by Drs. Anne Dorrance, Ron Hammond, Andy Michel, Laura Lindsey, and Pierce Paul. Save the dates. Registration details will be available in December.

 

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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.