CROP SCENE INVESTIGATION - 3

Where did the corn plants go?

by DAVID TOWNSEND

What do you do when only 8,000 lonely corn plants have emerged in your fields three weeks after planting?

That’s a question Clint, a corn grower from Lambton County, had for me when he called in early June. “My corn is just not coming. I planted before my neighbours and their fields are all up with good emergence,” he said disappointedly.

To help Clint get to the root of his problem, I needed answers to some simple questions. He told me that all his fields had the same problem. He also noted that he had planted several different hybrids, so I was quickly able to rule out a problem with a specific hybrid or seed lot.

We also discussed his fertilizer and herbicide program. His fertilizer program appeared in order, which would rule out fertilizer burn as a potential cause. His pre-emerge herbicide was applied at the proper stage and there was no heavy rainfall after application that could have washed it into the ground and caused damage to the seed.

Clint noted that he used treated seed, which would provide adequate defence against soil-borne insects. My final question was on planting depth. “I planted at an inch and three-quarters, the same as always,” Clint said. “My planting speeds were normal and the soil was in good condition.”

There was only one place to find the answer to this dilemma, so I headed for Clint’s farm. When I looked at his fields, the populations ranged from 8,000 to 12,000 plants per acre, well below the number required for top yields. Typically, growers should consider replanting if plants number fewer than 20,000. But before we talked about replant considerations, we needed to determine what happened in the fields.

As I walked, I noticed an odd pattern. Emergence was stronger in heavy clay areas, while fewer plants had emerged in areas of soft, loamy ground. I then decided to find some seed. I began digging in the loamy soil in several seed rows, but had no luck finding any seed so I decided to dig deeper. Finally, at four inches, I started to find seed consistently. Most of the seeds were still pushing upward, but they were rapidly running out of energy and many would not emerge.

I then did some digging in the areas of the field that were predominantly clay and showed better emergence. Here, the seeds could be consistently found two and a half inches deep.

Clint was surprised to hear my findings. We talked about planting and he maintained that he did nothing new or different. The speeds were the same, he didn’t work any deeper, the soil was in good condition and the planter settings were the same as last year. With the mystery still unsolved, I told Clint that I would come back the following day to do plant counts and we would review his replant options.

When I returned, Clint greeted me with some information that turned out to be the missing link in our puzzle. He remembered that he had replaced the disc openers on his planter in February. Finally, the mystery was solved. BF

The challenge
Do you know why Clint’s corn seed was planted so deep? Send your solution to Better Farming at editor@betterfarming.com

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

David Townsend, CCA, is the Technical Services Manager for NK Brand, Syngenta Seeds and based in Arva, Ont.