University of Illinois Extension Ogle County
Agricultural News
http://web.extension.uiuc.edu/ogle/agnews/
For more information, please contact:
Ogle County Unit
421 W Pines Rd, Ste 10
Oregon, IL 61061
Phone: 815-732-2191 / Fax: 815-732-4007
E-mail: ogle_co@extension.uiuc.edu
You are probably looking through yield information and checking markets each day to determine which crop to grow and which hybrid or variety to plant next year. We have included a summary of the corn following corn, corn following soybeans and soybean variety trials in northwest Illinois. Thanks to our plot cooperators (Bill Horst and Forrest Floto in Ogle County) and the participating seed companies for helping provide us with this information. Also thanks to Jim Morrison for doing the statistical analysis of the common - entry plots.
These results are summaries of the plots that had all of the same varieties or hybrids in common. You can see that the corn following corn yielded about the same as corn following soybeans this year. This was the case in most of Illinois. I have been asked why this occurred this year. It seems as though when we have good weather in general, the penalty for growing corn after corn is smaller. Here are some other observations that may help explain the rotational advantage or lack there of.
Low rootworm pressure in general. We are not sure why this occurred and as you know it is hard to predict.
Transgenic hybrids have done a good job of protecting yields from pests. Soil insecticides also worked well this year.
Dry weather early and plenty of moisture late allowed for great root development and very little early season disease problems that are associated with corn following corn.
A warm, dry May erased the cool soil factors that are usually associated with reduced yields in corn following corn.
Maybe these factors will help you as you determine your rotation for 2008 and beyond.
- Bill Lindenmier, Unit Educator, Ogle County
Fungicide Use on Corn and Soybeans
There has been much interest in and definitely an increase in use of fungicide on corn in Illinois this last year. Did it pay off is the big question. As with many crop inputs, the short answer is yes in some spots and no in others.
Dr. Carl Bradley, plant pathologist with the University of Illinois Extension, has compiled several different sets of yield information comparing untreated corn and corn treated with fungicides. Fungicides such as Headline (BASF), Quilt (Syngenta) and Stratego (Bayer Crop Science) are products containing strobilurin chemistry. Quilt and Stratego also contain a triazole that provides a different mode of action of control.
A composite of University trials in eleven Midwestern states along with Maryland and Ontario, Canada showed what I mentioned earlier; sometimes it paid and sometimes not. When we put numbers to the results using $3.50/BU for corn and an average of $20.00 treatment cost, the point where is paid to treat is a 6 BU increase. In some areas this cost was closer to $25, but $20 was used to determine the break even point.
Here are some of Dr. Bradley's observations.
16 out of 31 (52%) hybrids had a yield increase of 6 BU or greater in hybrids with fair to poor resistance to Grey Leaf Spot.
47 of 121 (39%) had an increase of 6 BU or greater where the hybrids were considered to have good to excellent resistance to Grey Leaf Spot
Overall, a foliar fungicide application would have been profitable 38% of the time with a mean of 3 bushel per acre increase by treating.
The previous crop did not make a difference on the profitability of the treatment. In other words, treatment of corn following corn did not significantly increase the probability of being profitable.
This evidence does not make a strong case for treating corn with fungicides. Many of you have results from this year that show a different outcome, especially in northern Illinois. Let's take a look at why this is not necessarily conflicting information.
Corn leaf diseases, especially Grey Leaf Spot need moisture to infect and reproduce. Northern Illinois had plenty of moisture in August, increasing the chance of positive outcome from treatment since some other areas had no rain and very little disease.
The resistance to diseases plays a big role in whether treatment is warranted. Your seed representative and agronomists should have a very good idea of which hybrids are less susceptible to leaf diseases.
I observed little or no disease pressure at early tassel in fields I was scouting. Some areas simply may have been infected sooner than others.
Timing, coverage, temperature and humidity at application time could have an effect on how well the fungicide works.
When corn is $3.50 and average yields are increasing, it is logical we want to protect as much of this yield as possible. Here are things to consider before deciding to treat with fungicides next year.
As you are choosing hybrids now, ask your seed rep about disease resistance. I am confident there are hybrids from many companies that would have good enough disease resistance that treatments would have a low probability to increase yield under most conditions.
Look at the leaves starting 3 below the ear leaf and higher. If there is no disease present, chances are good that treatment will not be as profitable.
Observe the weather and look at the forecast. If it has been dry and the predictions are for continued dry weather, you should probably save your money. Most fungal pathogens grow best in hot, humid conditions.
Read the label of the fungicide. Most of these are vague about when to treat – "before disease is present and 7-14 day intervals if conditions for disease development persist". This makes it tough to decide since we need to apply before the disease is present but we do not recommend treating if there is no disease.
Talk to your crop protection representative. There is evidence that fungicides sprayed before tassel emergence caused some problems with ear development and severe yield loss last year. Follow the manufacturer's recommendations on treatment timing and use of adjuvants. Also make sure tank mixes with insecticides have been tested and labeled by the manufacturer.
Don't spray because your neighbor is spraying. The probability that your fields are exactly the same as theirs is virtually zero.
Plan to leave an untreated check to determine if treatment worked in your field.
A final recommendation is to avoid repeated use of the same type of chemistry to delay resistance to fungicides. These are some of the same products we will need to help control soybean rust. Fungicide use on soybeans is a topic I will discuss in future newsletters.
- Bill Lindenmier, Unit Educator, Ogle County
News Tidbits
Good news from insect suction traps around the state. The traps captured practically no winged soybean aphids flying to overwintering sites this fall. This should indicate low numbers at least early next spring.
How is your crop of winter annuals? Soybean cyst nematode specialists at Purdue say, "We have evidence that the life cycles of winter weeds and SCN do overlap and the potential exists for SCN population increases on winter annual weed hosts, especially in fields with high densities of these weeds." Researchers say with the warm fall and early harvest, your henbit and deadnettle crops emerged nicely, and are nurturing your SCN.
The overwinter growth of SCN depends substantially on the number of degree days while it has a host crop, such as henbit and purple deadnettle. They are not physically active when the soil temperature is below 50 degrees, and complete a life cycle within 750 degree days or one month at 75 degrees. Purdue researchers say SCN will survive on deadnettle roots even when its lifecycle is interrupted for 20 days at 32 degree soils.
100,000 soybean plants at harvest requires how many to be planted in the spring? IA State agronomists found plant mortality was 9.1% greater in 30 in. rows than in 15 in. rows over 4 seeding rates. Planting 125,000 seeds per acre give 108,000 plants in 15 in. rows and 96,000 plants in 30 in. rows. Planting more seed increased plants but not yield.
In order to reduce seeding rates and still achieve 100,000 plants per acre at harvest, equipment setting, residue management, planting depth, and planting speed are more important than anything else, says IA State's Palle Pedersen. Seedbed conditions are a critical component as well. Plant early, but only when seedbed conditions are adequate.
