What's Going On In Your Fields This Summer?

Veteran ISU Extension crop specialist offers his observations and answers to questions he's receiving from farmers.

As the calendar turns from June to July, George Cummins, a veteran Iowa State University Extension field agronomist at Charles City in northeast Iowa, offers the following observations about this season's corn and soybean crops. He also answers some of the questions he's been getting from farmers.


The recent hot, muggy weather jump-started the corn and made delayed side-dressing or postemergence weed control applications more difficult, he points out. Growing Degree Unit accumulation is enhanced by night-time temps greater than 50 degrees F. and daytime temperatures warmer than 85 degrees F if there is no moisture stress.


"We start each growing season optimistically with 100% of some yield goal and then start subtracting because of delayed planting, poor stands, pest pressures, weather stress, etc.," says Cummins. "Each farm has a different set of circumstances. Some have suffered severe reductions due to planting delays,  hail, green snap, ponding, delayed weed control, etc. With the warmer weather and the crop response, optimism for their 2009 crop has returned for many."


"Some of the best beans I've ever seen"


Soybeans do not thrive in cool wet conditions common to the 2009 growing season that we saw during June. "The soybeans that are at the V4 growth stage (3 trifoliates unrolled) are the best beans I've seen – but not a very big "factory" to support high yields," says Cummins. "Flowering can start anytime now so the soybean plant will be dividing it's energies between reproduction and additional vegetative growth."


There are a lot of weedy soybean fields this summer in Iowa, he notes. Research has shown that early season weed competition reduces soybean yields.


ISU and many crop professionals recommend that a pre-plant or pre-emerge herbicide be used to compliment a glyphosate post program. Weedy fields where it is difficult to row the beans can be cleaned up but the competition and yield reduction have already occurred. Because of the delayed weed control, many of the early season broadleaves (giant ragweed, lambsquarter, and waterhemp are more difficult to kill with glyphosate alone, even at higher rates.


Volunteer corn is a problem this year


Corn harvest was difficult last fall and in some cases was not completed until after the New Year began. Pre-harvest and harvest losses from last fall's corn crop were higher than normal, making volunteer corn a problem in 2009, particularly if it was glyphosate tolerant or GT corn.


There are several herbicides that will take volunteer corn out of soybeans, says Cummins. They are Assure, Fusilade, Fusion, Poast, Select, etc.


But what about volunteer corn in corn? What can you do in that situation? The solution to volunteer corn in corn is mechanical—you'll have to cultivate, he says.


The photo below, taken by Cummins this spring, is an extreme example of GT volunteer corn in GT corn. The 2009 corn hybrid is likely a triple stack with corn rootworm resistance, European corn borer resistance and glyphosate tolerance and a seed cost greater than $100 per acre. This part of the field was cultivated. The corn in the rest of the field was tilled to destroy the corn and was planted to soybeans. With the narrow profit margins this year, there will be little return to management in this cornfield infested with volunteer corn.



With increasing use of glyphosate in both corn and soybeans, the risk of misapplication to susceptible crops, drift and/or sprayer contamination increases. Visible symptoms can be misleading when disease, weather stress or other herbicide modes of action are also involved.


The South Dakota State University diagnostic lab can document glyphosate exposure. More information is available at their website:

http://anserv.sdstate.edu/ then in the left hand menu click on "Services" and then "Pesticide Residues." The fee is $80/ sample.


Growing demand for weed-free forages


There is an increasing demand for weed free forages and bedding. The Iowa Crop Improvement Association (ICIA) has initiated a Forage and Mulch Certification Program. The program includes a formal application; field inspection prior to cutting and harvesting; a labeling process and a transit certificate allowing interstate shipment. For more information check out the ICIA website :www.agron.iastate.edu/icia/.


"I'm also getting some questions from farmers wanting to know if they can collect carbon credits for practicing no-till," says Cummins. "Carbon sequestration, carbon credits, and cap and trade are new concepts to many of us but these topics are in the news as Congress debates legislation to slow climate change."


Since 2003, landowners have had the opportunity to register and sell carbon credits on the Chicago Climate Exchange (CCX) and generate additional income. Further information is available at www.agragate.com


Soil conservation has been a continuing priority and residue management has been a primary strategy for over 25 years, notes Cummins. Adoption of these practices has lagged in spite of the introduction of herbicide-tolerant hybrids and varieties; appropriate equipment for high-residue systems; research and educational efforts; and financial incentives.


Why don't we see more no-till in Iowa?


In 1992 Pete Nowak, a rural sociology professor now at the University of Wisconsin and who used to be at Iowa State University, published an article on why farmers do or don't adopt new techniques and technologies like those related to residue management systems. Different approaches must be used for those who don't know; those than know but can't;  those that know but won't and those who don't know and don't care.


"For at least 17 years we have used "educate, regulate or bribe" tactics with limited success," says Cummins. "We will need to identify and understand  our farmers and their individual needs and logic if we are to increase the rate of adoption of residue management practices. Nowak's article should be considered as we develop strategies for the future."


Will it pay to spray foliar fungicide this summer?


"Advertisement campaigns have begun and we are starting to get calls about the merits of fungicide applications on both corn and soybeans," says Cummins. "Since the 2006 growing season various trials have been conducted at both Nashua and Kanawha on both corn and soybeans related to timing of application, product comparisons, disease incidence with and without fungicide treatment and corn hybrid and soybean variety response."


Results of these trials are found in the ISU Annual Reports for the last three years. You can find them on line at www.ag.iastate.edu/farms/ then click on "Farm Progress Reports" , the specific year, and scroll down to either the "Northeast Farm" (Nashua) or the "Northern Farm" (Kanawha).      


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