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ISSUE #11  July 12, 2001

 

QUICK QUO PRO-QUESTIONS FROM QUERIES ON CORN AND SOYBEANS

Compaction problems are still seen in some of my fields, should I chisel this fall?

Only if soil is dry so that the hard pan can be shattered adequately will compaction be allowed to be reduced. The cold winter with heaving and thawing can also help some with compaction problems, but heavy compaction may need more work. The key to soil tilth is to limit any compaction causing operations, if possible. Working soil tilth to higher organic matter content also helps moderate compaction.

What causes corn plants to produce an ear on top of the plant?

Crop genetics along with high fertility can cause ear development in the tassel area of the plant. This may occur when the plant sustains hail or mechanical damage early in plant development. Yields shouldn't decrease from a few plants showing this characteristic.

What causes that ugly corn smut in fields?

Common smut is caused by disease introduction from Ustilago maydis. It can be severe when the infection invades young, actively growing, wounded plant tissue.

Can leaf disease affect corn yields?

Yes. Severity and length of time infected can all have an affect on corn yield. Difficult to estimate yield loss, each case may be different.

Under poor root growth conditions, can additions of zinc or iron help out corn or soybeans?

If either of these micronutrients or other nutrients are limiting, additions may help in the case of corn. In soybeans, by the time the symptoms are showing it is usually too late to benefit from additions. It is really worth the money to soil test, especially on corn in order to make sure that nutrient needs are available to the crop. A soil test also confirms that the symptoms are micronutrient related and not a symptom of poor environmental conditions.

Is there an antagonistic effect to Roundup if zinc is added with ammonium sulfate for an application on a Roundup-Ready crop?

Calcium and sulfate additives can be antagonistic to Roundup unless antagonism can be overcome with AMS addition, especially if alkaline water is used as the carrier. One of the new micronutrient products being used is Zink-Gro, a white zinc sulfate monohydrate that is 100 percent water soluble. It is immediately available to the plant if water saturated soils do not dilute the product beyond the plants roots reach. However, the sulfate in the product may create some mixing particularities that must be overcome to get the full herbicide benefit from a tank mix treatment. Check beyond a simple compatibility test to see if manufacturers have plot data examining proposed tank mixes.

Can I make my last Roundup treatment on my Roundup-Ready soybeans with a tank mix of insecticide for thistle caterpiller control?

First, carefully determine if you have the numbers and are in the insect life cycle to warrant treatment. The numbers may now be coming down and the 25_30 percent defoliation suggested prior to bloom by NDSU or the 20 percent threshold after bloom or pod set may not be present. Three of the chemicals that may be effective, Sevin XLR, Warrior and Asana may be fine to tank mix with Roundup (see ND Weed Control Guide, page 76). The other possible insecticides, Pounce, Lorsban, Pencap-M and Scout X-tra, should be checked for tank mix compatibility through the manufacturers to confirm if their use is fine in a tank mix.

When would be a good time to get rain on my corn and soybean crops from now into fall?

Moisture stress two weeks before and after pollination of both crops can cause yield reductions. Available soil moisture or light showers that supplement water supplies would be great during the four weeks around pollination, as long as your soybean field does not have a history of white mold problems combined with high population numbers. Crops that skirted the hail swathed areas and remained untouched and were off to a good start this year are looking good. This week's crop progress report for 7-9-01 reported 80 percent of the ND corn and 56 percent of the MN corn in good to excellent condition. In soybeans, 80 percent of the ND soybeans and 52 percent of the MN soybeans were reported as good to excellent.

What are the water requirements for corn and soybeans once we get past flowering on the crops?

According to the normal requirements as researched through the University of Nebraska, the inches of irrigation water needed, assuming no rainfall or soil moisture, are as follows:

Corn

Blister kernel (R2) 10.5 inches per acre
Dough (R4) 7.5
Beginning Dent (R4.5) 5.0
Full Dent (R5) 2.5
Physiological maturity (R6) 0.0

Soybeans

Full pod (R4) 9.0 inches per acre
Beginning seed (R5) 6.5
Full seed (R6) 3.5
Beginning maturity (R7) 0.0


My crops were destroyed, what should I do for the balance of the summer and fall?

If a cover crop was not used, consider needs for not having fallow syndrome next year. Soil testing is in order based on the crop planned for next year. An intensive soil sampling program will determine nutrients needed for next year's crops. Also, consider checking on the need for deep tillage to prevent plow pan compaction in areas where equipment may have caused extra compaction this year or consider practices that will allow a more minimum till or no till system to be utilized in following years.

With several of the past years having cool spring conditions or cooling weather once crops emerged like this year, should earlier hybrids and varieties be used next year?

The old standby saying to plant 50 percent in the normal maturity range, 25 percent of an earlier variety and 25 percent of a slightly higher variety provides different genetics and a range of maturities to adapt to the season, no matter what the weather throws at us next year.

What kind of disease pressure such as stalk rot in corn can we expect to show up in August and September this year?

Temperature and a final talley on insect pressure as well as a final total on early season damage will all have to be considered. So far European corn borer to our south and east has been light, if temperatures cool moderately to limit disease at the end of August and into September without any surprises there should be few problems. Field with early season pressure from hail or flooding should be watched a little more closely to insure that if these fields show lodging problems, the corn crop in these areas can be harvested in as timely a manner as possible.

Will European corn borer (ECB) have an effect on ear retention this fall?

If light pressure from these insects continues this year, we probably will see very limited problems. Once ECB has been found in an area, keep a tighter watch on the field to make sure any conventional corn remains below treatment thresholds.

Where can I get more information on corn and soybeans throughout the season?

An electronic list serve is being used to get out daily information by computer to corn and soybean grower in ND and MN. Information is sent to you by E_mail as the information becomes available. The E-mail list is not shared with others and to subscribe, log on to http://www.topica.com/lists/cornbean/  and sign up for the free service or send an E-mail to: cornbean_subscribe@topica.com . Updated information on both crops is also available on the nearly 50 pages included on our Web site at: http://www.ag.ndsu.nodak.edu/aginfo/rowcrops/index.html . Best viewed under Explorer as the browser, soundbytes, pictures, links and information are all included on the pages that were funded through ND SBARE funds from the Corn Council and the Soybean Growers.

Now that I have finished my weed control for the cropping season, what should I be doing in my corn and soybean fields?

Scouting to prevent problems this season and for the next. Once flowering has occurred, scouting may be slowed from every week on each field down to every week and a half or two. Consider summarizing seasonal records and looking at what is needed for harvest and fall tillage to insure smooth operations during those hectic times.

Denise McWilliams
Crop Production Specialist

dmcwilli@ndsuext.nodak.edu


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