Crops: Crop Scene Investigation - 12: Why is Glen's corn corkscrewed?

Saturday, May 10, 2008

His seed wasn't the issue. But there was evidence of compaction and the nights had been cold, with temperatures dropping to zero in early May. Could that be the problem?

by DEAN SHANTZ

If you notice that your corn crop isn't coming up like it should, do you call for help right away or do you take a wait-and-see approach?

Glen, a grower in Bruce County, knows that a prompt diagnosis is in the best interest of his crop and bottom line. He called me in early May, 2007 about one of the fields he had planted in the last week of April. "It's not looking very good," he said. "The stand is uneven and there are several gaps where no corn has emerged."

Upon further questioning, Glen remarked that, besides missing plants, some of the seedlings appeared "corkscrewed" and had "leafed out" as though they were trying to open up underground.

I made an appointment with him to see the field. This wasn't the first call I had received from growers. Although spring planting conditions were good for the most part, there were some cases of emergence problems in corn.

The field in question was a clay loam soil that had been dry enough to plant the last week of April. "I planted treated seed at a depth of 1.5 inches," said Glen.

While the majority of the field was clay loam, there were spots of heavier clay, loam, lighter sand and a gravel base. As I walked the field, I could see the emergence problem was not consistent across the field. I asked Glen about the crop the year before.

"It was wheat," he said. "We had a wet harvest and chisel plowed in the fall."

I wasn't surprised to hear this as I saw evidence of compaction due to the heavy equipment running across the field.

"What about your crop protection program?" I wondered aloud. Glen had incorporated a grass herbicide prior to planting. After an inspection of his cultivator, it was evident that the herbicide had been effectively applied and incorporated to a depth of two inches. That ruled out any suspicions of herbicide injury.

Glen hadn't checked soil temperature, but he reported that the nights had been cold and the mercury had dropped to zero on May 7.

I took note of some surface soil crusting and Glen confirmed that there had been some cold rains since planting. Overall, the soil conditions were somewhat cloddy, wet and tight.

I decided that it would be a good precaution for our lab to check the seed lot. Fortunately, Glen had kept the seed tag and we were able to perform both warm and cold germ tests. The results came back satisfactory - the seed wasn't the issue.

With that confirmation, I was able to pinpoint what was wrong. Compaction and crusting were definitely at play here, but they had only compounded the real problem. I assured Glen that the culprit was out of his control as I explained what was going on.

Can you positively identify the problem with Glen'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 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

Dean Shantz, CCA, is a Field Agronomist for NK® Brand, Syngenta Seeds. He is based in Tavistock.