Crop Scene Investigation - 39: The mystery of the fallen corn trail

Saturday, November 3, 2012

by BERNARD TOBIN

It was supposed to be just another day scouting fields for certified professional crop consultant Mervyn Erb.

On this bright, sunny June afternoon, Erb travelled just east of Exeter to inspect a cornfield for Jack, one of his grower customers. The cornfield had a large population of tufted vetch, and Erb wanted to see whether the herbicide he had prescribed to take out the perennial legume was doing the job.

Touring the field on his ATV, Erb was pleased with what he saw. The herbicide had delivered the control he was looking for and the three-leaf corn was healthy, vetch-free and full of yield potential. But then, out of the corner of his eye, Erb spotted something odd – two corn plants, side by side, lying flat on the ground. As he approached the fallen plants, he noticed two plants in the next row in the same condition.

"As I looked into the distance I could see the same pattern across the field. It was a little trail of two corn plants lying on the ground," recalls Erb. "The corn was small, so I started to drive my ATV across the rows, following the path. I found where it started and then doubled back to where it ended. I measured it using my range finder and it was 1,167 feet long.  It was the strangest thing."

The first explanation that came to Erb's mind was cutworm, but he quickly dismissed that idea."You usually see cutworm on black sand or black muck soils. But Jack's field was clay." The pattern also left Erb bemused. "Cutworms don't move across a field and cut down two plants in every row."

He was also puzzled with what he found at the point where the dead plants first appeared in the field. "The trail was Y-shaped. At the beginning, there were two trails where a single plant was cut. Then it quickly converged and two plants were cut across the remainder of the trail."

Erb decided to take a closer look at the clipped corn plants. Most of them appeared to be cut clean, but on some of the plants you could see the imprint of teeth marks on the stalks. "I looked for animal tracks, but I didn't really see anything because the soil was crusted."

He did note that the clipped plants were very fresh and were just beginning to wilt. The plants had to have been cut the night before, so he headed back across the trail looking for clues. Based on the teeth marks, he had a good idea what was behind the caper, but he needed more proof.  As he walked across the trail of fallen corn plants, he found what he was looking for – clusters of small round manure droppings.

Do you know what took a bite out of Jack's corn field? Send your solution to Better Farming at: rirwin@betterfarming.com or by fax to: 613-678-5993. All the answers will be pooled and one reader will win a Wireless Weather Station. BF