Crop Scene Investigation - 48 Solved: Attack of the underground leaf eaters

Thursday, January 2, 2014

When crop consultant Mervyn Erb started digging in Jason's cornfield, he unearthed the largest population of nightcrawlers he had ever seen.

"About four inches below the surface, we found all kinds of earthworms, including some of the biggest nightcrawlers I ever set eyes on," recalls Erb. "That explained the dime-sized holes in the soil. With the size of these suckers, they were able to grab the corn leaves that were touching the soil and drag them underground."

Unfortunately, Jason's efforts to increase the organic matter in the soil on his new farm also created a tremendous environment for the high worm population in the field to explode and create a corn-eating army.

"The worms had obviously propagated all fall, fuelled by the wheat straw and cover crop that had been plowed down during last fall's wet weather," explains Erb. "In the spring, having munched their way through all the organic matter, they set their sights on the corn that was growing above ground."

The backward spring growing conditions had created uncharacteristically short plants with long leaves that were touching the ground. With leaves within reach, the nightcrawlers pulled them underground to continue feeding.

Erb and Jason agreed that the field needed to be rotary-hoed to help unlock the thousands of plants per acre that were growing sideways because their leaves were anchored in nightcrawler holes. Erb notes that Jason actually had to rotary-hoe the field twice. "After the first pass, the nightcrawlers again started pulling the plants underground."

Erb admits this nightcrawler story appears to be a rare case, but he believes Ontario farmers may see it more often, thanks to the significant growth of cover crops in recent years.

Congratulations to Wayne Beattie, Stayner, for his correct answer. "We had the same thing happen this year," Wayne notes. He adds "it was explained to me that we do everything we can to promote a healthy environment for these creatures, but they are blind, so when they come out at night to eat they can't tell the difference between trash and corn plants that are touching the ground!" BF