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Ontario field crop pest roll call

Ontario field crop pest roll call

As photos of critters fill farmers’ news feeds, a certified crop advisor shares which ones may cause the most problems this season

By Jackie Clark
Staff Writer

Farmers and agronomists are using social media and virtual communication tools more frequently than ever due to advancing technology and, this year in particular, the physical distancing protocols put in place to protect against COVID-19. That technology has changed the game for pest scouting in Ontario fields and allowed us to stay on top of quickly evolving trends, certified crop advisor Patrick Lynch told

“The whole crop production diagnostics and remedies have changed drastically in the last three years,” he said. “The information is getting out to more people quicker.”

Lynch has been monitoring armyworm as they come up from the United States.

Armyworm has “been a little bit worse than average,” he said. “It’s not a real bad year … but there are hot spots.”

The moths of the species fly north into Ontario fields over a period of several weeks.

“Now we’re into the peak flights that came in, and it’ll dwindle out and we will continue to have some more hot spots probably in spring grain, maybe even into corn,” Lynch explained.

“Armyworm moths will be laying eggs and there will be feeding damage probably over a three- to four- week period. I believe that if you go into any wheat field that’s 40 to 50 acres, you can find armyworm,” he said. “Sometimes there’s a little bit of a panic because of the devastation that armyworm can do.”

That panic may lead growers to spray whole fields where it may not be necessary. Natural armyworm predators, like parasitic wasps, should also be active right now.

“We don’t have the technology yet but it’ll be coming quickly, where we’ll be able to use satellite imagery to (identify) where the hot spot is,” and precisely spray regions within a field, Lynch added.

There are a few other pests farmers should have their eyes on.

“Right now, we are recommending to growers to be very vigilant about leafhoppers,” Lynch said. The potato leafhopper typically arrives from the south in June.

“This year (leafhoppers) are at serious numbers earlier,” Lynch explained. “They will continue to be a pest probably until the first of August. The fields that are going to be most at risk are going to be new seeding alfalfa, established alfalfa under dry conditions, and all edible beans. I would expect most edible bean crops are going to need to control potato leafhopper.”

Cutting an alfalfa field may cause the pest to migrate to any adjacent edible bean fields, he added.

“Once they do severe damage on edible beans, it’s hard to” control them, Lynch added.

Though we had a cool start to the season, recent weather favours insects.

“In general, hot dry weather favours insects and cool wet weather favours diseases,” said Lynch. “This would suggest that everybody should be on the lookout for soybean aphids” around the first week of July.

“When you find them, watch them,” advised Lynch, and hope natural predators keep them below recommended thresholds.

Spider mites are another pest that pose an issue for growers each year.

“They’ll start around the edge of the soybean field,” Lynch explained. “If you can spot them and are vigilant … you can spray the edge of the field and then just count on the fact that they will not be bad enough in the rest of the field.”

A pest that remains a mystery is western bean cutworm.

“We don’t have a good handle on scouting techniques,” Lynch said. “I believe that the western bean cutworm has changed rather dramatically.”

Field scouts used to be able to monitor adults and then predict the timing of eggs hatching to spray a field for proper control.

“That’s all been thrown out the window … we don’t know what’s going on,” Lynch added. For now, growers and agronomists will have to continue to observe the pest to try to get a handle on new patterns.

Seedcorn maggot and wireworm appeared earlier in the season, and have been building year over year, Lynch added.

“We have no good control strategy,” he said. So producers should keep an eye out for next season.

“You’ve got to keep checking the fields or hiring a scout to do it, because we’ve seen a lot of different things already this year. Nothing to suggest that we won’t be seeing a lot more before the year is over,” Lynch said.

ossyugioh\iStock\Getty Images Plus photo


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