Crops: CROP SCENE INVESTIGATION – 16 - Why are Rick’s beans defoliating?


When a crop suddenly takes a turn for the worse, don’t wait until it’s too late. Get some advice to preserve your yield potential. That’s what Rick did when he called me about one of his soybean fields in the early part of August.

“My beans are dying,” said the Norfolk County grower. “They have been great all summer, but now the leaves are starting to drop off.” Rick’s soybeans were at the R1 to R2 stage of growth, and should have been blooming.

Before I could ask any questions to help diagnose the problem, Rick proposed a hypothesis. “It’s worse on the edge of the field by the ditch banks and it moves into the field from there. It’s like a drift pattern,” he said.

CROP SCENE INVESTIGATION – 14 Solved: Why is corn breaking down in Chuck’s best dirt?

by David Townsend

Sidewall compaction during planting was the source of trouble in Chuck’s corn.

It was simply too wet when he headed to the field with the planter.

As Chuck rolled over the wet soil, the planter’s disk openers applied horizontal pressure and compacted the sides of the seed row.

If the soil had stayed wet, the seedling roots would have been able to push through the wall and establish a root system. But the weather turned dry and the walls hardened so much that the roots couldn’t penetrate through. Instead, they grew along the path of least resistance – down the seed slot creating tomahawk roots. As a result, they were unable to access the moisture and nutrients required to grow and prosper.

CROP SCENE INVESTIGATION – 15: What caused wilted patches in Paul’s soybeans?


Even ideal growing conditions can pose challenges to soybean production. That’s why I wasn’t surprised when Paul, a grower in Grey County, called saying that there was trouble in his beans. “Patches of plants throughout the field are wilting, drying down and turning brown,” he said. “Can you come and check it out?”
It was the first week of August and the entire field should have still been green and growing.

The symptoms were obvious when I arrived in my truck later that day. You could easily see the wilting patches from the road and the damage was even more extensive along the tree lines.  

CROP SCENE INVESTIGATION – 13: What set back two rows in William’s corn?– Solved


The two rows in Williams corn were set back because they didn’t receive the appropriate fertilizer due to a mud ball plugging an opener.
Knowing the planter got stuck in a wet hole helped to pinpoint the equipment as the problem. Results of the plant tissue test showed that the two rows were low on nitrogen and phosphorus compared to the other rows. Instead of going into the soil to help the plant, the fertilizer landed on top of the soil.

Crops: CROP SCENE INVESTIGATION – 14: Why is corn breaking down in Chuck’s ‘best dirt?’


I was sure that it was serious when I got a call from a corn grower who said that stalks were mysteriously breaking down in his ‘best dirt.’ Growers know their fields. They know that, when a particular piece of ground delivers year after year, there is cause for concern when things don’t look right.

Chuck, a grower from Simcoe County, called from his field just before harvest. “My stalks are breaking down in my best dirt, but they’re standing up in the poor dirt. What’s happening?” he asked.

I knew the field Chuck was talking about. It has a gravel knoll up near the barn and the opposite, lower end is where he’s harvested some of his best yields. What he described was definitely backwards.

CROP SCENE INVESTIGATION – 12 SOLVED: Why is Glen’s corn corkscrewed?


Cold injury caused Glen’s corn to corkscrew, contributing to an uneven stand.
The cold nights and rains after planting caused the corn seed to absorb cold water and experience cold injury or “inhibitional chilling injury.” This affected germination, delayed seedling growth and even caused some plants to leaf out underground and have a corkscrew appearance.

Damage due to cold injury is most severe when temperatures remain at or below 10 C for an extended period of time after planting. While this contributed to Glen’s uneven stand, it wasn’t the only factor. Cases like these often involve more than one culprit.

Crops: CROP SCENE INVESTIGATION – 13: What set back two rows in William’s corn?


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.”

Crops: CROP SCENE INVESTIGATION 11: What was behind Sam’s uneven soybeans? – Solved


It turns out that seed corn maggots caused Sam’s soybean stand to be thin and uneven.
Don’t let the name deceive you. Seed corn maggot is not only found in corn. It’s a common pest in soybean and vegetable crops throughout the province.

Damage caused by seed corn maggot can be difficult to distinguish from other insects and disease, but two features made it an easy diagnosis in Sam’s field – spring-applied manure and cotyledon feeding.

Crops: CROP SCENE INVESTIGATION – 10 SOLVED: What’s really stressing John’s corn?


Rootworm larvae damaged the roots in John’s corn causing the plants to look severely drought- stressed.

The key to solving this puzzle was getting as much information as possible from the field history. Typically, rootworm is a pest found in corn after corn. While John’s previous crop had been soybeans he’d had significant volunteer corn pressure.