In the fight against diseases in winter wheat in Eastern Canada, the agri-food industry has done a remarkable job in effectively managing fusarium head blight — for decades considered the crop’s greatest disease threat. Seed companies have screened and eliminated susceptible varieties while timing of fungicide applications has advanced to the extent that fusarium is seldom the overwhelming infestation it was in 1996.
Yet fusarium isn’t the only concern among growers and their cereal crops. Leaf rust, septoria, powdery mildew and tan spot can be problems in any year in winter and spring wheat as well as in oats and barley, which explains Corteva Agriscience’s decision to launch Cerefit, a new fungicide co-pack recently registered for use across Canada.
Cerefit is a dual mode-of-action, with a Group 11 (picoxystrobin) and a Group 3 (propiconazole) that provide preventive and curative activity. Neither active is new but the combination offers growers a new option in managing leaf diseases at critical times.
In the West, Cerefit will protect oat and barley crops at the early flag-leaf stage against leaf diseases, which can reduce yields by as much as 20 per cent. In the East, winter wheat will be the target crop, with Cerefit applied at the three- to six-leaf stage and a similar estimate of 20 per cent yield protection potential (according to research from Agriculture and Agri-Food Canada [AAFC]).
In Eastern Canada, Cerefit can be applied with Pixxaro herbicide to help combat Canada fleabane, which is now resistant to three different herbicide groups (Groups 2, 9 and 22).
Know the numbers
Corteva Agriscience product manager Lorne Thoen says growers generally have a dollar threshold they’re willing to invest in order to manage risk on certain diseases, depending on their potential severity and impact on yield or quality. On their own, leaf diseases might cost a grower up to 20 per cent of their yield. But with a disease like fusarium, losing 20 per cent of yield is only part of the problem: the remaining 80 per cent will be a challenge to market because of the presence of the pathogen. With that cost in mind, it’s an easier choice to invest money to manage fusarium and count on a lesser impact from leaf diseases.
“It’s all about managing risk from that winter wheat standpoint,” says Thoen, who’s based in Saskatoon. “You can have a grower with a good catch coming out of winter and a few broadleaf weeds. But they’re thinking, ‘It’s moist out, I have some warm afternoons and days that are going to create a good environment for that disease to stand in there. So I want to spray something for weeds and I’m going to throw in a fungicide to take care of that (disease environment).’”
Another tool in the toolbox
As with many innovations coming to market for growers, Cerefit represents a newer option, while maintaining the list of options in other fungicides. Thoen likens it to purchasing a new socket wrench: it may be easier to use and more effective in many cases but it doesn’t make an old half-inch wrench obsolete.
“Not only do we get a nice dual mode of action from the two fungicide modes but picoxystrobin is more preventative,” Thoen says. “Propiconazole is also a preventative but it also has curative qualities. To have another tool that’s a dual mode of action that’s both preventive and curative is always good but it doesn’t mean you’re not going to use the other tools that you have.”
As for the need for dual mode of action products in disease management, Thoen concedes that diseases are unique compared to weeds: the latter are a perennial challenge for growers whereas the former requires the pathogen, a host and a favourable environment in order to flourish. Yet in his time in the industry, Thoen has learned to never say “Never!” when it comes to taking a wait-and-see approach with diseases.
“Weeds are living plants that evolve and diseases are living organisms that evolve and change,” says Thoen, adding that resistance to disease might not be as critical as it’s become with weeds, yet it’s only a matter of time with diseases. “If you look at what’s coming out on the market from the industry, there are new modes of action fungicides and pre-mixes, and I don’t think there’ll be many single modes of action that come out.”
In addition to offering growers another option in the fight against Canada fleabane, using Pixxaro (halauxifen + fluroxypyr) in concert with Cerefit enables growers to accomplish two tasks with a single pass. As competitive as winter wheat can be on most species, it’s good to provide growers with another effective active ingredient against the troublesome species. As Thoen indicates, combining the fungicide and herbicide application also opens a window of opportunity for custom applications. By the time a fungicide application becomes necessary at the three- to six-leaf stage in winter wheat, many growers are fully engaged in planting corn or soybeans. Combining Cerefit and Pixxaro alleviates some of that timing concern.