May 28, 2014
Tom Hillyer, Hillyer Agriservice, found a few fields with significant injury from black cutworms. All corn fields should be regularly scouted for black cutworm injury until the corn plants reach V5. For more details, see http://www.extension.iastate.edu/Pages/eccrops/blackcutworm.html.
Corn plant with below ground feeding by black cutworm. (Courtesy of Tom Hillyer)
The black cutworm (near the soil line on the knife blade) that damaged the plant in the previous picture. (Courtesy of Tom Hillyer)
Fomesafen Carryover in Corn
Fomesafen is the active ingredient in Flexstar and Reflex as well as several generics, such as Battlestar, Dawn, Rhythm, Ringside, Rumble, Shafen, Topgun, etc., and in combination with other active ingredients in several products, such as Flexstar GT, Flexstar GT 3.5, Marvel, Prefix, Statement, etc. Fomesafen was applied to many soybean fields in 2013. The Flexstar label states that corn should not be planted for 10 months after Flexstar application, and in many fields, corn was planted less than 10 months after the fomesafen application. In addition, the dry weather in 2013 slowed down the normal rate of chemical breakdown. The cold winter may also have reduced the amount of breakdown that would normally occur.
Corn injured by fomesafen carryover will exhibit veinal chlorosis; the veins will be chlorotic while the interveinal material will remain green. (Sulfur deficiency is the exact opposite, with the veins remaining green and the interveinal material becoming chlorotic. This is often seen in low organic matter areas without a history of animal manure and in instances where rapid top growth outpaces root development and the ability to move sulfur into the plant rapidly enough.)
Fomesafen carryover in corn. Source: http://www.weeds.iastate.edu/mgmt/qtr00-1/flexstar.htm
Sulfur deficiency in corn. (Courtesy of Brian Lang)
Corn normally recovers quickly from fomesafen injury. I am not aware of any instance where yield loss due to this injury has been documented.
For more information, see Bob Hartzlers article at http://www.weeds.iastate.edu/mgmt/qtr00-1/flexstar.htm and Kevin Bradleys (University of Missouri) article at http://ipm.missouri.edu/ipcm/2014/5/A-Lot-of-Calls-about-Carryover/.
Late Spring Soil Nitrate Test
The earliest planted corn is approaching the time to check the N status of the soil by taking one-foot depth soil samples when the corn is 6-12 tall. At least 16 soil cores (24 is better) should go into each sample and about a cup of this (soil bag full) sent to a lab for analysis. Cores should be pulled in a systematic way going across corn rows (i.e. first core pulled in the row, next one-1/8 the distance between rows, next 1/4 the distance between rows, etc.). For more information on the process see https://store.extension.iastate.edu/Product/Nitrogen-Fertilizer-Recommendations-for-Corn-in-Iowa. An information sheet for sending samples to ISU is at http://soiltesting.agron.iastate.edu/Late%20Spring%20Soil%20Nitrate-Nitrogen%20Test%20for%20Corn%20form.pdf. The cost for analysis is $5/sample.
FOR YOUR CALENDAR
Cover Crops for Forage and Grazing Field Day
10:30 a.m., Thursday, June 5, 2014
June 10, 1:30 p.m. - Chariton
June 11, 9:00 a.m. - Ottumwa
June 11, 1:30 p.m. - Mt Pleasant
June 12, 9:00 a.m. - Muscatine
June 12, 4:30 p.m. - Bettendorf
June 13, 9:00 a.m. - Cedar Rapids
10:00 a.m., Tuesday, June 10, 2014
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
Details are at: http://www.aep.iastate.edu/feel/early.
Cover Crop Workshop
9:00 a.m., Thursday, June 12, 2014
Details are at: http://www.aep.iastate.edu/feel/cover.
Cover Crops Field Day
12:30 - 3:00 p.m., Thursday, June 19, 2014
Dick Sloan Farm, 3046 Harrison Ave, Rowley, IA. More details wil be coming soon.
Spring Field Day Northeast Research and Demonstration Farm
1:00 p.m., Tuesday, June 24, 2014
Details are 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
Details will appear at: http://www.extension.iastate.edu/Pages/eccrops/meetmusc.html.
Hay & Forage Expo
June 25 26, 2014
Spring Field Day Southeast Research and Demonstration Farm
1:00 p.m., Thursday, June 26, 2014
In addition, training for Certified Crop Advisors will be conducted, beginning at 9:00 a.m.
Details are at: http://www.extension.iastate.edu/Pages/eccrops/meetserc.html.
Weed Science Field Day
8:30 a.m., Thursday, June 26, 2014
Further details will be forthcoming.
Mid-season Crop Management Clinic
9:00 a.m., Wednesday, July 9, 2014
Details are at: http://www.aep.iastate.edu/feel/mid.
Late-season Crop Management Clinic
9:00 a.m., Tuesday, August 19, 2014
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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