T3 wheat fungicide — to spray or not to spray?

With T3 fungicide application timing approaching to control fusarium in Ontario’s wheat crop, many growers are wondering whether to spray or not to spray.

With the hot, dry Ontario weather pushing into late May, there’s little or no disease in the crop and disease levels could decline further if moisture continues to be scarce. For RealAgriculture agronomist Peter Johnson, the decision to spray a fungicide in wheat comes down to two key factors: “how dry is it going to stay and how hot is it going to get?”

If the weather becomes more moderate, disease levels could increase and wheat plants could benefit from fusarium protection. Adequate moisture and a reprieve from the early-season heat could also mean a longer grain filling period, which would allow the crop to benefit from a T3 fungicide’s ability to enhance plant stay-green, says Johnson. He notes that U.K. research has shown that yield will increase three bushels per day, for every extra day the plant stays green during the grain fill period.

As long as the weather cooperates from a rainfall and temperature perspective, T3 fungicides will deliver as advertised, says Johnson. “They will keep it green and bring added yield to the table, but if it goes crazy hot then all bets are off.” To support his point, Johnson reminds us of the the hot, dry grain fill conditions that growers in Ontario’s Essex and Kent Counties experienced during 2020. It was too short and too hot and T3 herbicides delivered very little yield bump.

Johnson, and other agronomists attending a virtual Exeter/Mount Forest Agribusiness meeting on Tuesday, agreed that it’s too early to give up on a wheat crop that still has significant yield potential and can capture a strong market price.

Pioneer agronomist Greg Stopps noted that a significant portion of the crop has not yet reached the T3 timing and growers have some time to mull over their decision. “I would be a little worried if there is rain in the forecast or if humidity is starting to go up again through that flowering window,” said Stopps during the meeting. Under these circumstances, forgoing the application would elevate risk.

BASF agronomist Rob Miller said it’s just too early for Ontario growers to give up on the wheat crop. “We haven’t even hit flowering. We’re just coming out of the boot,” said Miller, noting there are more moderate temperates in the forecast and some rain potential.