By Darrell Smith, Farm Journal Conservation and Machinery Editor
Originally published in Farm Journal, January 2014
A defensive strategy should include understanding corn diseases, scouting fields and following a management plan
If corn growers compiled a list of their greatest corn disease threats, gray leaf spot, northern corn leaf blight, southern corn leaf blight and Goss’s bacterial wilt would be right at the top. Gray leaf spot would earn its ranking because it’s so widespread. Northern and southern corn leaf blight can sneak in and take you by surprise. Goss’s wilt is moving into new areas at an unprecedented rate.
All those diseases can slash yield. “They attack corn leaves, which function like a plant’s solar panels, taking in energy that is used to produce food,” says Farm Journal Field Agronomist Ken Ferrie. “When leaves are damaged or killed, it affects ear size, stalk quality and standability because when the plant can no longer manufacture food, it cannibalizes itself.”
For complete article visit: http://www.agweb.com/article/big_four_yield_threats_naa_darrell_smith/
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By Darrell Smith, Farm Journal Conservation and Machinery Editor
Originally published in Farm Journal in January, 2012
Step-by-step guide to identify lacking micronutrients
Micronutrients are essential for plant health. You can apply a micronutrient mix that, you hope, will prevent problems or you can learn to identify the symptoms and treat only if you find a problem. Farm Journal Field Agronomist Ken Ferrie recommends the latter approach.
“Micronutrient deficiencies can be serious—if you have them,” Ferrie says. “But problems with micronutrients usually are driven by some other condition, such as compaction, drought, organic [muck or peat] soils, sandy soils and acid or alkaline soils. If possible, solve the micronutrient issue by fixing the underlying cause.
“The environment tells us where to expect micronutrient issues,” he adds. “Elsewhere, it’s rare to find a problem.”
Neither crop scouting, soil testing nor tissue testing is sufficient, by itself, to diagnose a micronutrient deficiency. It requires a combination of all three.
Take the detection process step by step, Ferrie says.
For more information: http://www.agweb.com/article/micronutrient_deficiency_detection/
By Tom J. Bechman
Originally published by Farm Progress in September, 2011
Sixty days after corn kernels start to develop, the black layer should form. Corn is physiologically mature at that point, and nothing can affect what’s in the kernel. Depending upon where you live, a portion or all of your crop may be at that stage. Especially in the eastern Corn Belt, however, there may still be a few days or weeks to go. “Even where corn was three weeks behind in planting, it was only one week behind by grain fi ll,” says Bob Nielsen, a Purdue University corn specialist. The native Nebraskan maintains the Chat’n Chew Café website used by corn growers throughout the country.
■ Corn kernels with a milk line aren’t physiologically mature.
■ Moisture content can vary widely at black layer.
■ Harvest maturity means harvest won’t greatly damage kernels.
For more information: http://magissues.farmprogress.com/ipf/IN09Sep11/ipf021.pdf
By R.L. (Bob) Nielsen
Agronomy Dept., Purdue Univ.
West Lafayette, IN 47907-1150
Email address: email@example.com
- Unusual twisted growth of whorls noted in some fields.
- Likely caused by sudden return to good growing conditions.
- Yield effects are minimal, if any.
Whilst walking corn fields today (like every good corn grower should be doing regularly early in the season, I might add!), I noticed something that I had not seen just a few days ago. Scattered plants throughout the field were exhibiting unusual twisted growth. The whorls of the affected plants were tightly twisted, often bent over severely, and not unfurling on a timely basis.
One’s natural instincts would blame the twisted growth on herbicide injury, especially those characterized by the cell growth inhibitor mode of action. Where such herbicides are applied pre-plant or pre-emergence, shoot uptake of the herbicide by the emerging seedling can result in twisted growth. But, in some cases, the cause is something entirely different.
For more information: https://www.agry.purdue.edu/ext/corn/news/articles.00/Twisted_Whorls-0527.html
By Rhonda Brooks, Seeds and Production Editor
Originally published in Farm Journal in April, 2014
Sometimes you have to dig a little for answers when your corn crop emerges unevenly, which can hurt ear counts, says Missy Bauer, Farm Journal Associate Field Agronomist. Bauer provides these simple directions to determine the causes of uneven emergence.
1. Dig up a corn plant, look at the root system and find the old seed. Note that the mesocotyl extends up to the base of the crown.
2. Hold the base of the crown at the 3⁄4″ line of the measuring tape, as demonstrated in the photo above. Then, measure the length of the mesocotyl down to the bottom of the seed. This measurement is your planting depth for that specific plant.
3. Measure the planting depth of neighboring plants. Look for variations in the mesocotyl length
between plants and compare your findings. Any variations tell you there was a lack of planting-depth uniformity. Plants that vary 1⁄4″ or more in planting-depth consistency can reduce ear size or count.
Technology Development by Monsanto
Originally sourced from the Illinois Agronomy Handbook, 23rd edition and the Purdue Corn & Soybean Field Guide, 2007.
Assessing Corn and Soybean Stands
As corn and soybeans emerge, evaluating the stand is important to identify problems from planting, insects, or disease. Evaluating your stands early can help you identify concerns while there may be time to remedy them.
Three common methods for taking stand counts are outlined below. The 1/1000th acre method is widely used for corn and wide-row soybeans. A more accurate method is the wheel method, which counts 150 plants and measures the distance from start to finish with a measuring wheel. The hoop method is often used for drilled beans.
For more information: http://www.thefieldposition.com/wp-content/uploads/2012/05/Assessing-stands.pdf
By Pam Smith
Originally published in Farm Journal in August, 2011
Rootworms are rascals. The latest evidence of this comes in the first documented case of resistance by a field population of western corn rootworm in northeastern Iowa.
An Iowa State University team led by Aaron Gassmann responded to producer concerns that Bt hybrids expressing the Cry3Bb1 protein were exhibiting significant larval damage. Gassmann’s report in the PLoS ONE scientific journal reveals how he collected western corn rootworm adults from those fields and found that the progeny from those parents able to survive on Bt corn hybrids expressing the Cry3Bb1 toxin at levels higher than western corn rootworm from fields not exhibiting significant larval damage.
For more information: http://www.agweb.com/article/crop_tech_rootworms_grow_up_resistant/