Greig: Lessons learned from Ontario crops’ pest pressures

Stripe rust overwintered further north than usual going into the 2016 growing season, Cargill’s Linda Freitag said at SWAC. (OMAFRA photo)

The warmer winter and subsequent drought defined the 2016 cropping season in Ontario, resulting in more disease and insect pressures and then challenges managing them.

Three agronomists gave an overview of the 2016 cropping season at the SouthWest Agricultural Conference in Ridgetown, outlining challenges and wins for the year.

Leanne Freitag, Cargill’s manager of agronomy for Ontario, outlined challenges with wheat, Steph Kowalski of Agronomy Advantage outlined soybean challenges and Russ Barker of DuPont Pioneer outlined the most unpredictable of 2016 crops: corn.

Ontario had record wheat yields, but that rapidly-growing wheat exposed some crop management gaps.

Freitag said she’s surprised at how many growers don’t apply sulphur on wheat, adding it’s simple to do and inexpensive.

“If you’re putting fertilizer on, make sure sulphur is in there,” she said. As the wheat grew rapidly towards a record yield, more sulphur deficiency symptoms showed up in the Ontario crop.

“Putting on 10-20 lbs. of sulphur is really important, and cheap to put on,” she said.

Where there’s a deficiency, the advantage can be 20 bushels of yield difference, she said. Watch the nitrogen to sulphur ratio: It should be 10:1 to 7:1.

Stripe rust was also an issue in wheat for the first time in memory. The disease overwintered further north than usual, Freitag said, and resulted in more damage than normal.

The greater prevalence of the disease showed which varieties of wheat are resistant and which are not. There is a significant difference, Freitag said, but cautioned not to base variety decisions only on resistance to stripe rust. Plant the best variety for your fields, and spray if required.

“Stripe rust is the biggest yield robber of any of the foliar diseases in wheat,” said Freitag. “It can take 50 per cent or more of your yield.”

Spray when symptoms are seen, she added. “Keeping the flag leaf clean is critical.”

The wheat crop came out of the soft winter with little winter kill, which likely helped the wheat put down roots deep enough that it was able to find enough moisture to pull through the dry summer. Altogether it resulted in a record wheat harvest.

Spider mites everywhere

Soybeans pulled through the summer drought in Ontario in most cases — but not for lack of trying by some insects.

Scouting is the best way to stay ahead of spider mites, Kowalski said. Treat the crop with timely spraying. Be careful what insecticide is used, however, as you don’t want to take out all the beneficial insects, along with the spider mites.

Weed control was a challenge for soybeans in 2016, as there often wasn’t enough moisture to activate pre-emergent herbicides. If the weather is hot and dry, spray early in the morning for systemic herbicides and in the evening for contact herbicides.

Fungicides made sense on soybeans, said Kowalski, as long as you got a timely rain. She says use the whole decisions tree on whether or not to spray fungicides. Don’t just not do it because of weather.

Barker said he worries about blanket recommendations to spray fungicides, due to potential resistance and other overuse issues. “It gives me the heebee-jeebees.”

Good base fertility was important to pulling soybeans through to good yield in 2016.

Unpredictable corn

There were times this growing season that Russ Barker just told farmers to stay out of their corn fields. The fields were just too depressing to visit. He also told them that the fields would yield better than they expected, and he was right about that.

A wise plant breeder once told him that cob size was a poor indicator of potential yield, he said. More important is the depth of kernels and kernel flex. The strongest hybrids will produce a deeper kernel late into the growing season.

“Remember that the growing season is a marathon, not a sprint,” he said.

The response of corn to fungicides is well documented — an average seven to eight bushels per acre advantage, he said. Each farmer has to determine if it makes sense economically on their farm.

Where it does make sense, he said, is on silage corn and corn fed to hogs, as the fungicide reduces mycotoxin load for hogs and dairy farmers need to maximize the quality of feed going into the feed bunk.

Two other unpredicted and especially frustrating problems appeared with the corn harvest last year. The first is the amount of Gibberella ear rot on corn, which surprised the industry by showing up in high levels of infection.

“We’re not a whole lot smarter on Gibberella. We still can’t predict it very well.”

Western bean cutworm (WBC) was also a larger issue as it overwintered further north than usual, and continued its long-term growth into new areas of the province.

The WBC was first seen in Ontario in 2008 and became economically significant in 2010, Freitag said. The problem in 2016 is that it appeared in fields where farmers had scouted and didn’t find egg masses.

“We can’t scout with a high level of assurance that it won’t be an issue,” she said. The industry has to sort out how to monitor for the pest, but the answer likely lies in paying closer attention to trap numbers.

Farmers need to make economic and risk assessment decisions on whether or not to spray for WBC, at least until better biotech solutions for control, such as the Viptera trait, are bred into more widely used hybrids.

— John Greig is a field editor for Glacier FarmMedia based at Ailsa Craig, Ont. Follow him at @jgreig on Twitter.

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