- DTN Headline News
Dr. Dan Talks Agronomy
Wednesday, September 2, 2015 12:36PM CDT

By Daniel Davidson
DTN Contributing Agronomist

Corn is rapidly moving through dent stage (R5). Excess rain early in the summer, shallow roots, shortages of nitrogen and a dry August have contributed to corn moving through grain fill more rapidly than expected. Any stress, including a shortened grain-fill period would reduce kernel weight by hindering dry matter accumulation.

Scouting now can help you decide when corn fields will be ready to harvest and how to prioritize fields in order to minimize harvest loss and maximize harvest efficiency. I like to note the variety, planting date and stress it might have endured as I do these last checks.

We're always looking for comparison years. Some have linked the 2015 season to 2008, a cropping year that started off early with good planting conditions and then, it rained and remained cool most of the summer. Much of the corn didn't mature before the first hard frost in 2008 and we were harvesting corn well into December. Much corn never did reach physiological maturity and it never dried down in the field on its own. Storing corn was a nightmare that winter.

We had plenty of planting delays in 2015 resulting in some late replanting, but it looks as though most of the crop will mature on time this year. Once corn begins to dent, it takes another 20 to 25 days to reach black layer or physiological maturity (R6). If dent occurred in mid to late August, corn should mature by the last week of September, well before the first hard frost hits.

Check stalk strength. Corn has been under some late-season stress as evidenced by premature senescence in many parts of the country. This is putting demands on the plant for carbohydrates to fill the ear as soon as possible. If the plant can't provide those demands through photosynthesis, it will begin to rob it from the stalk. This will weaken the stalk and allow stalk rots to move in prematurely and this increases the risk of fall lodging.

Fields differ in their susceptibility to lodging due to the hybrid planted, field conditions, the amount of stress encountered and if the plant was sprayed with a fungicide to maintain plant health. As we move into September, you can pinch the stalk above first node or push the stalk to see if it is weakening, which is a sign that lodging could happen. Harvest fields most at risk first. For more information on stalk rots go to: http://bit.ly/…

Check of stalk nitrates: Symptoms of nitrogen deficiency were evident in many fields in June and July due to heavy rains. Premature die back suggests corn did not have enough nitrogen to carry it to full term. A post-mortem stalk nitrate test can provide an assessment of whether the crop had the right amount of nitrogen, too much nitrogen or if nitrogen was limiting.

To test for nitrate in the stalk, cut 8-inch-long sections of stalk starting 6 inches above the soil surface from 10 representative plants. Cut these samples into 1-to-2-inch-long segments to facilitate drying and send to your local analytical laboratory. Stalks can be sampled between one quarter milkline to about three weeks after black layer.

Results will be in parts per million. If less than 700 ppm, nitrogen was limiting. If between 700 and 2,000, nitrogen was sufficient. If greater than 2,000, the available nitrogen was greater than needed. It's too late to help this year's crop, but it will give you some good information to make management decisions next year.

For more information on late season stalk nitrate testing go to: http://bit.ly/…

Dan Davidson can be reached at AskDrDan@dtn.com

Follow Dan Davidson on Twitter @dandavidsondtn

(PS\SK)


blog iconDTN Blogs & Forums
DTN Market Matters Blog
Katie Micik
Markets Editor
Monday, August 31, 2015 4:36PM CDT
Wednesday, August 26, 2015 8:41PM CDT
Monday, August 10, 2015 5:59PM CDT
Technically Speaking
Darin Newsom
DTN Senior Analyst
Tuesday, September 1, 2015 10:04AM CDT
Tuesday, September 1, 2015 10:03AM CDT
Tuesday, September 1, 2015 10:03AM CDT
Fundamentally Speaking
Joel Karlin
DTN Contributing Analyst
Friday, August 28, 2015 12:10PM CDT
Thursday, August 27, 2015 6:00PM CDT
Wednesday, August 26, 2015 3:41PM CDT
DTN Ag Policy Blog
Chris Clayton
DTN Ag Policy Editor
Thursday, September 3, 2015 7:29PM CDT
Tuesday, September 1, 2015 1:14PM CDT
Monday, August 31, 2015 6:53PM CDT
Minding Ag's Business
Marcia Taylor
DTN Executive Editor
Wednesday, September 2, 2015 8:19PM CDT
Thursday, August 20, 2015 9:10PM CDT
Friday, August 14, 2015 5:17PM CDT
DTN Ag Weather Forum
Bryce Anderson
DTN Ag Meteorologist and DTN Analyst
Thursday, September 3, 2015 9:54PM CDT
Wednesday, September 2, 2015 2:11PM CDT
Friday, August 28, 2015 8:23PM CDT
Thursday, September 3, 2015 7:02PM CDT
Wednesday, September 2, 2015 5:37PM CDT
Tuesday, September 1, 2015 6:59PM CDT
DTN Production Blog
Pam Smith
Crops Technology Editor
Thursday, August 27, 2015 5:36PM CDT
Tuesday, August 25, 2015 4:00PM CDT
Monday, August 17, 2015 4:50PM CDT
Harrington's Sort & Cull
John Harrington
DTN Livestock Analyst
Tuesday, September 1, 2015 11:18AM CDT
Wednesday, August 19, 2015 7:16PM CDT
Friday, August 7, 2015 7:20PM CDT
South America Calling
Alastair Stewart
South America Correspondent
Wednesday, September 2, 2015 4:29PM CDT
Tuesday, September 1, 2015 2:43PM CDT
Wednesday, August 26, 2015 3:48PM CDT
An Urban’s Rural View
Urban Lehner
Editor Emeritus
Monday, August 31, 2015 11:44AM CDT
Monday, August 24, 2015 11:09AM CDT
Monday, August 17, 2015 4:53PM CDT
Machinery Chatter
Jim Patrico
Progressive Farmer Senior Editor
Thursday, September 3, 2015 5:53PM CDT
Wednesday, August 26, 2015 12:25PM CDT
Thursday, August 20, 2015 4:12PM CDT
Canadian Markets
Cliff Jamieson
Canadian Grains Analyst
Thursday, September 3, 2015 8:02PM CDT
Wednesday, September 2, 2015 10:05PM CDT
Tuesday, September 1, 2015 9:12PM CDT
Editor’s Notebook
Greg D. Horstmeier
DTN Editor-in-Chief
Tuesday, August 25, 2015 5:57PM CDT
Wednesday, August 19, 2015 4:58PM CDT
Wednesday, July 29, 2015 4:02PM CDT
 
Copyright DTN. All rights reserved. Disclaimer.
Powered By DTN