Iowa State University Extension and Outreach

East-Central and Southeast Iowa Crop Information

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May 15, 2014

 

CORN

 

How will Corn Planted In April Fare?

 

It appears that most corn planted in April is doing well. However, be sure to watch fields to confirm that corn is emerging properly and there is a good stand. 

 

Depending on the individual situation, potential issues are:

1.  Corn planted several days before the ground cooled may experience “cork-screwing” as it attempts to emerge,

2.  Corn planted just before the ground cooled may have experienced “imbibitional chilling” (absorbing cold water), which may cause the seed to swell but have little germination, and

3.  Pythium seedling rots promoted by cool, wet soils.

 

In the event that a field or portion of field does not have the desired stand, refer to Roger Elmore’s (Extension Corn Production Specialist) article at http://www.agronext.iastate.edu/corn/production/management/planting/replanting.html for guidance.

 

Corn Seedling Diseases Wanted – Really!

 

Alison Robertson, ISU Extension Plant Pathologist, is studying corn seed and seedling diseases.  If you encounter fields with seed / seedling disease problems, please let Alison or me know; samples of diseased material will help the study greatly, and the study will likely improve farmers’ ability to manage these diseases in the future.

 

Be Sure Soils are Fit to be Planted

         

According to the latest USDA report (http://www.nass.usda.gov/Statistics_by_State/Iowa/Publications/Crop_Progress_&_Condition/2014/IA_05_12_14.pdf) we still have quite a few acres of corn to plant, especially north of Highway 20. While the desire to get back in the field as soon as possible is great, mudding it in to achieve that goal will likely cost more yield than delaying planting a day or two. The most recent Iowa planting date data, which can be found at http://www.agronext.iastate.edu/corn/production/management/planting/recommendations.html, suggests that areas in eastern Iowa south of Highway 20 can expect 95 – 100% of yield if planted by May 13 – 15; unfortunately north of Highway 20 (where planting is farthest behind) the 95 – 100% yield timeframe ends about May 2. Most recent data also shows that yields do not drop off as rapidly after the ideal planting dates as had been previously observed, and that yields drop off at about 0.5% per day, at least for the first few days; see the Iowa data at http://www.agronext.iastate.edu/corn/production/management/planting/replanting.html and some Illinois data at http://bulletin.ipm.illinois.edu/?p=2066. 

 

Small mistakes made at planting time can haunt you the rest of the season. Some points to consider with corn planting this spring:

 

1.   Don’t plant into wet soils. This can lead to sidewall compaction which can lead to season-long problems. The roots will have difficulty growing through the compacted zone made by the planter and will be pancaked into a flat plane in the direction of the planter. This can lead to uneven corn growth, rootless corn, and K deficiency symptoms due to poor root growth. Poor root growth will be an even greater problem later if the summer turns dry.

2.   Don’t plant too shallow. When soil moisture is plentiful producers are tempted to plant corn more shallow. For every corn field I see with problems caused by planting too deep, I see a hundred fields with problems caused by planting too shallow. If the seed ends up being less than 1.5 inches deep, problems such as rootless corn and K deficiency symptoms are much more likely to occur. Even if the seed is placed 1.5 inches deep, sometimes the soil can settle after planting or there can be soil erosion so that the plant actually “sees” a more shallow depth. Corn should be planted 1.5-2” deep and error on the deep side; many people say to just shoot for 2” deep.

3.   Plan for corn stands of 34,500-37,000 plants per acre. Ideal corn seeding rates have been increasing at the rate of about 400 seeds/A/year. Average corn yields per plant haven’t changed much in the past 50 years. Most of the yield gain has been from breeding corn that can tolerate an increased population. If you are still planting the same population you did 10 years ago, you’re paying 2014 seed prices and only getting 2004 yields.

4.   Pay attention to details at planting. A little extra time making sure planter settings, seed spacing, depth, and population, and soil conditions are correct can pay big dividends.

 

How Long Do I Have to Wait After Applying Anhydrous Before Planting?

 

It is often recommended to wait 7 days after applying anhydrous before planting, but in reality there is no magic numbers of days to wait to prevent fertilizer burn to corn. I have seen stand reductions even when the nitrogen is applied in the fall, and corn can be planted immediately after application without problems. The main thing is to be sure to apply the anhydrous 7-8 inches deep and get a good seal. Most of the anhydrous will diffuse to a zone about 6 inches in diameter within 24 hours. If the anhydrous is applied 8 inches deep and you are planting 2 inches deep, you will still have the anhydrous zone 3 inches below the seed. When the anhydrous is applied when the soil is too wet, more will diffuse closer to the soil surface. One way to reduce future problems is to apply the anhydrous at an angle to the corn rows so if there are injury problems later you won’t be taking out entire rows of corn. At this point in the season, it may be time to switch priorities and think about getting the corn planted first and worry about the nitrogen later.

 

Should I switch my maturity?

 

A general rule is that if planting is delayed until May 25, you should select a hybrid that matures five days earlier than an adapted full-season hybrid for that area. If planting is delayed another seven days, select a hybrid that matures another five days earlier than the previous one. In general, the date to switch maturities is later in southern Iowa.

 

 

SOYBEANS

 

Bean Leaf Beetle

 

A few soybean fields have already been planted.  These fields, fields planted to food-grade soybeans, and fields with a history of bean pod mottle virus should be monitored for bean leaf beetle activity as they emerge.  However, it appears there will not be wide-spread problems with bean leaf beetles on emerging soybeans in 2014.  Erin Hodgson, Extension Entomologist, and Adam Sisson, Extension Program Specialist, noted that bean leaf beetle survival is probably much below normal this year; see http://www.extension.iastate.edu/CropNews/2014/0409hodgson.htm.  Tom Hillyer, Hillyer Agriservices, noted that he is seeing very few bean leaf beetles on emerged volunteer soybeans, which is another indicator of a low overwintering population.

 

FOR YOUR CALENDAR

 

Cover Crops for Forage and Grazing Field Day

10:30 a.m., Thursday, June 5, 2014

Gladbrook, IA

Details are at: http://www.extension.iastate.edu/ilf/content/iowa-learning-farms-host-field-day-tama-county.

 

Pasture Walk

10:00 a.m., Tuesday, June 10, 2014

Farley, IA

Location:       Eric & Amanda Gaul farm, 26946 Dyersville East Road, Farley.

Topics:           Paved lanes, waterlines, Millionaire Model Dairy Farms, and conventional and organic dairy budgets, all discussed by Dr. Tranel, ISU Extension Dairy Specialist.

Directions:    From Holy Cross (Highway 52), go south on County Hwy Y13 (Holy Cross Road) for 6.7 miles. Then turn west on Dyersville East Rd for 1.4 miles.  The farm will be on the left.

From Farley (Highway 20), go north out of Farley 4.7 miles on County Hwy Y13, then turn west on Dyersville East Rd for 1.4 miles.  The farm will be on left.

 

 

Early-season Crop Management Clinic

9:00 a.m., Wednesday, June 11, 2014

Boone, IA

Details are at: http://www.aep.iastate.edu/feel/early.

 

Cover Crop Workshop

9:00 a.m., Thursday, June 12, 2014

Boone, IA

Details are at: http://www.aep.iastate.edu/feel/cover.

 

Cover Crops Field Day

Thursday, June 19, 2014

Rowley, IA

Further details will be forthcoming.

 

Spring Field Day – Northeast Research and Demonstration Farm

1:00 p.m., Tuesday, June 24, 2014

Nashua, IA

Details will appear at: http://www.extension.iastate.edu/Pages/eccrops/meetnerf.html.

 

Spring Field Day – Muscatine Island Research and Demonstration Farm

5:30 p.m., Tuesday, June 24, 2014

Fruitland

Details will appear at: http://www.extension.iastate.edu/Pages/eccrops/meetmusc.html.

 

Hay & Forage Expo

June 25 – 26, 2014

Boone, IA

See: http://hayexpo.com/

 

Spring Field Day – Southeast Research and Demonstration Farm

1:00 p.m., Thursday, June 26, 2014

Crawfordsville, IA

In addition, training for Certified Crop Advisors will be conducted, beginning at 9:00 a.m.

Details will appear at: http://www.extension.iastate.edu/Pages/eccrops/meetserc.html.

 

Weed Science Field Day

8:30 a.m., Thursday, June 26, 2014

Ames, IA

Further details will be forthcoming.

 

Mid-season Crop Management Clinic

9:00 a.m., Wednesday, July 9, 2014

Boone, IA

Details are at: http://www.aep.iastate.edu/feel/mid.

 

Late-season Crop Management Clinic

9:00 a.m., Tuesday, August 19, 2014

Boone, IA

Details are at: http://www.aep.iastate.edu/feel/late.

 

 

 

If you have any questions, please feel free to contact the Iowa State University Extension Office.
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Last Update: May 15, 2014
Contact: Virgil Schmitt vschmitt@iastate.edu


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