Crops: Crop Scene Investigation - 13: What set back two rows in William's corn?

Sunday, November 2, 2008

by DAVID TOWNSEND

I'm a big advocate of field scouting and figure you'll always learn something by walking your fields. On rare occasions, you might come across something that challenges even the most experienced agronomist.

William, a Brant County grower, offered me a real brain teaser when he called last June. On a walk-through to evaluate the need for a re-spray in his six-leaf corn, he came upon a section of plants which were set back compared to the rest of the crop. "This is really strange, but there are two rows that look delayed," said William. "It's nothing major, but I'm wondering what might cause something like this."

There are lots of possibilities. William assured me that everything looked consistent up until the three-leaf stage. The spring had been quite wet, but things had since dried up. "Are the affected rows a different variety from the rest of the field?" I asked. "Or could it be a case of sprayer overlap?"

William answered no to both questions. I wondered if any plants were missing. "No, they're all there. They just look sick," he said.

I suggested we wait a week or two before we took any action. In the meantime, I suggested he speak with the planter operator and ask if he recalled anything weird happening during planting.

The corn had reached the eight-leaf stage by the time I visited the field.

As William led me to the problem area, I noted that the headlands were fine, but the two rows in question were still lagging behind the rest of the crop by one or two leaves.
I started digging for clues. Everything had been planted at the same depth and the population was all the same. I also checked for bugs, but couldn't find any.

I went back to my first instinct that it was a sprayer issue. But the measurements for spray overlap didn't work out – the damaged area was too narrow to be caused by a sprayer.

I wanted to know more about what had taken place when the field was planted. I figured the seed had come from the outside hopper, and the subsequent pass with the planter had created the double row. William reported that the planter operator had planted two fields that day – this field first and then another one about 10 miles away. There was, however, one intriguing revelation. "There isn't any problem in the second field," he noted.

I asked if anything unusual had happened when he planted the first field. "The planter operator remembered getting stuck in a wet hole during the round of the headland and had to back out. Once he got started up again, the planter monitor kept going off and so he cleaned out the seed tube and away he went."

That piece of information put us closer to solving the mystery. I was even more confident in presenting my hypothesis when we came across some fertilizer granules sitting on top of the soil. I just needed to confirm my thinking with a plant tissue test.
Can you positively identify what happened with William's corn? Send your solution to Better Farming at: rirwin@betterfarming.com or by fax to: 613-678-5993.

Correct answers will be pooled and one winner will be drawn for a chance to win a Wireless Weather Station. The correct answer, along with the reasoning followed to reach it, will appear in the next issue of Better Farming. BF

David Townsend, CCA, is Crop Manager for NK® Brand, Syngenta Seeds. He is based near Clinton, Ontario.