As we get ready for spring planting, last fall’s serious DON infestation in cornfields throughout Ontario is still fresh on the minds of growers.
Shawn Brenneman, agronomic sales representative for Syngenta recalls the outbreak as the “perfect storm.” He’s referring to significant rainfall events combined with humid days before and after silking that led to high levels of DON contamination.
“It was widespread across the territory I cover – Lambton, Middlesex, Elgin – but there were definitely hot spots,” he says. “It affected most growers to some degree. For some, the level of DON within their crop was so high that it couldn’t be marketed and it had to be destroyed. In other cases, growers took a significant discount on their crop. The bottom line is that there was significant monetary loss to a lot of customers out there.”
DON – which is short for deoxynivalenol and also referred to as vomitoxin – is a mycotoxin that is a by-product of a Fusarium infection. There are hundreds of different species of Fusarium – some are more predominant than others and some are only pathogenic to certain crops. While the species that caused the issue last fall is specific to corn, the Fusarium pathogen could still affect other crops in the rotation.
“During the harvest of corn infected with Fusarium graminearum, the fungal spores disseminate in the air and settle in the soil. A lot of harvest residue also carries the pathogen, which ultimately goes into the ground,” says Abhi Deora, Seedcare™ Technical Lead at Syngenta. “The fungus will build up in the soil and this is where the problem can start for the next crop.”
He explains that once you have a huge build-up of a pathogen in the soil, all that is needed are environmental conditions conducive to disease, such as cold soils, and the crop is at risk. For soybeans, Fusarium graminearum is a species of significant concern.
“For the last two decades, it’s been considered amongst the top eight predominant species that can affect soybeans in Ontario and the second-most pathogenic species based on findings from Agriculture and Agri-Food Canada researchers,” says Deora, adding that the effects can be devastating. The three main diseases associated with Fusarium graminearum in soybeans are Fusarium root rot complex, seed rot and seedling blight; all of which can lead to huge plant stand and yield losses.
Seed treatments fill the gap
Currently, there is no varietal resistance that confers control of all of the Fusarium species in Ontario. Therefore, growers should count on seed treatments to protect their soybeans from the disease as part of their management program.
“Our studies indicate that Fludioxonil, an active ingredient in Vibrance® Maxx seed treatment, has strong activity on Fusarium graminearum in particular, but also has good activity on most of the other predominant species of Fusarium that we have in Ontario,” says Deora. “Seed treatments basically fill the gap – they’re the most effective, most efficient, and most economical method to control these pathogens,” he says.
Brenneman highlights the need for seed treatments in today’s soybean production practices. “As planting dates are being pushed earlier to get more nodes and more yield, seed is being put in colder-weather soil, so they stay in the ground longer, which makes them a little more susceptible. That’s where we need to have a quality fungicide in the package to protect that seed.”
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