Like most farmers, Tom has dealt with his share of insect pests. He’s encountered many different pests at his 6,000-acre mixed grain operation near Wadena, Sask., over the years, but this past August he came across a new insect that had him stumped.

Tom called me in early August to say he’d been out inspecting one of his barley fields at head emergence when he’d spotted some unusual little worms crawling around in the awns of some plants. He had no idea what they were, and because he’d already seen cutworms and flea beetles in his crop earlier in the season, he was worried this unfamiliar insect could cause further problems.

Tom asked if I could come out right away to help identify the worms. I arrived at his farm and started scouting the barley field, but I couldn’t see any sign of the insect.

Tom, like most producers in the area, had had a challenging year dealing with emergence and insect issues throughout the season, so I was aware that he’d been monitoring his crops very carefully to ensure nothing else went wrong. I knew there had to be something there or else Tom wouldn’t have called me, so I kept looking.

Finally, I encountered a barley plant with the insect Tom had described. I could see lots of the worms crawling around next to an armyworm that I also observed on the plant. Looking around, I spotted more worms and some cocoons on other barley plants and even on some wild oats that were also in the field.

I wasn’t sure what I was looking at either, but when I consulted my textbook on field pests to identify the insect, it became clear what this insect was and just what kind of threat it posed to Tom’s barley crop. When I informed Tom, the answer to those questions took him by surprise.

Crop Advisor’s Solution: Not all insects are pests

After consulting my textbook on field pests, I knew what I was looking at wasn’t a pest at all!

The worms and cocoons belonged to a beneficial insect called the Braconid wasp, which parasitizes caterpillar pests such as armyworms. Braconid wasps lay their eggs in the caterpillars, which then hatch and produce larvae that consume the caterpillars from the inside out.

The little worms I found with the armyworm were, in fact, Braconid wasp larvae, which had likely just emerged from the armyworm. Within hours of emerging from their insect hosts, the larvae will cocoon and continue their life cycle.

When I gave Tom the news, he was relieved to hear he didn’t have another problem insect on his hands. I told him nature has a way of taking care of pests, and I advised Tom to leave the Braconid wasps to do their job in his barley crop.

Reanne Denomie, PAg, CCA, BSc, works for Richardson Pioneer in Wadena, Sask.

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During the last week of August, I was crop scouting for Gerald, who farms 6,000 acres of wheat, barley, oats and canola just north of Wadena, Sask. I was recording the severity of fusarium head blight in one of Gerald’s wheat fields when I noticed something unusual.

It was well into the growing season and shortly before harvest, but the field had an uneven heading or maturation look to it. Some plants appeared to be further along than others, but they were contained within strips that ran in straight lines down the entire length of the field rather than in random patches.

In spite of the fact that Gerald had sprayed a fungicide for fusarium head blight earlier in the season, the disease was heavily present in some of these strips, while in other strips it was hardly noticeable.

When I called Gerald to point out the problem, he wasn’t quite sure what to think of the situation. “Your guess is as good as mine,” he said.

I assessed possible causes such as nutrient imbalance, poor seed quality, and environmental damage, but they were all ruled out — if any of these were to blame, a patchy pattern would have been the result, not the straight lines I saw in Gerald’s wheat field.

Herbicide burn was also disregarded, due to the fact that the leaves of the plants throughout the crop appeared to be in good shape aside from some leaf disease development.

It was only when I inquired into Gerald’s seeding methods that spring that I began to zero in on the root of the problem.

Crop Advisor’s Solution: Wheat irregularities caused by different seeding depths

When I asked Gerald about his seeding methods that spring I began to clue in on the source of the problem. He said the field had been seeded with two different drills, which had been set at different seed depths.

Gerald admitted that he’d been in a rush to seed the field as quickly as possible at the time, because of heavy rain in the forecast and his worry about not being able to finish the job on time. A drill with a different depth setting had been pulled in from another field to help complete the field.

This seed depth difference accounted for the different stages of plant development within the field, which in turn produced a similar outcome for the fusarium head blight treatment. That’s because fungicide applied to a field that is at inconsistent stages of development when it is sprayed will yield inconsistent results.

Fortunately for Gerald, the fusarium head blight in his wheat crop blended out and there was no yield or grade loss in this field compared to the rest of his farm. The producer was also able to take something away from the incident, as he learned the value of seeding depth consistency and proper seed bed establishment, as well as how one misstep at the beginning of the year can affect the crop for the whole season. This isn’t a mistake Gerald is likely to make again in the future.

Raeanne Denomie is a sales agronomist with Richardson Pioneer Ltd. at Wadena, Sask.

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John had sprayed his five canola fields with glyphosate in early June, but within two weeks he noticed that some weeds were still thriving and many were beginning to grow back. “It doesn’t appear that my herbicide worked, but I have no idea why,” John explained to me.

At John’s farm, I could see the weeds were indeed coming back to life — in some instances, the older leaves of the weeds had been killed off but the plants were still doing well. Apparently, the glyphosate had not translocated within the weeds.

After eliminating tank mixing error, incorrect water usage, sprayer malfunction and chemical failure as the cause of the problem, we checked the quality of the water John uses for pesticide application. Test results indicated John’s water was hard!

The calcium and magnesium salts in hard water bind tightly to the glyphosate molecules, stopping those molecules from binding to the active sites within the plant, hindering the ability of the glyphosate to kill the weeds.

By the time we determined the source of the problem, it was too late in the season to re-spray the canola fields. The weeds, no doubt, would outcompete the canola plants and have a negative impact on yield.

However, determining that poor quality water was to blame for the herbicide failure wasn’t all bad news because this problem is easily managed. Adding ammonium sulphate to the tank mix, for example, will ensure herbicide efficacy because it preferentially binds to the glyphosate molecules before the calcium and magnesium. The ammonium-glyphosate complex then binds to the active sites within the plant, eventually killing it. There are several other products on the market that work the same way as ammonium sulphate. However, with ammomium sulphate, much lower volumes of product are required, making them a more convenient option.

Ammonium sulphate has been shown to boost glyphosate’s efficacy in targeting larger weeds as well as increasing its rate of killing those weeds when used on summerfallow.

Water quality is an important aspect of herbicide application and should not be overlooked. In addition, there are other factors affecting water quality such as pH levels and the presence of organic matter that should be monitored. Farmers would be wise to evaluate water quality regularly and, if necessary, consider adding a treatment to avoid tying up herbicides. †

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