Fungicide re-evaluation has growers looking for alternatives

PMRA re-evaluation of chlorothalonil will make it more difficult to use

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Chlorothalonil, a broad-spectrum multi-site fungicide active ingredient found in horticulture fungicides, has been re-evaluated by the Pest Management Regulatory Agency (PMRA) for all uses within agriculture and turf.

It is part of PMRA protocol to re-evaluate pesticide products every 15 years, or sooner, as science evolves and new information, methodologies and approaches become available to ensure the use of the product continues to be acceptable with current standards.

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Why it matters: Bravo Zn and Echo, two products with the active ingredient chlorothalonil, are used often by horticulture growers and the regulation changes have added some additional challenges for managing diseases.

Bravo Zn and Echo have been used in Canada since the late 1970s.

Chlorothalonil contains multiple modes of action making these two products a low risk for resistance development among diseases.

“Where alternative products do exist for chlorothalonil, most are single site fungicides, which have a higher tendency for resistance development — some cases have already been documented in Canada,” says Chris Duyvelshoff, crop protection adviser with the Ontario Fruit and Vegetable Grower’s Association.

With Bravo Zn and Echo’s low resistance development traits, the products are a foundation for many disease control programs, says Duyvelshoff.

For most cases the number of permitted uses per season is decreasing, creating major challenges to growers.

“Potatoes will be most affected; their number of applications will be reduced, probably the bigger impact in general of the decision,” says Dennis Van Dyk, vegetable specialist with OMAFRA.

“Growers will need to look to alternative fungicides for disease control if available,” says Duyvelshoff. “For some crops there are several alternatives, such as potatoes, with some limitations, however some specific crops, such as celery, have very few alternatives.”

For the remaining 2019 season, growers are to use chlorothalonil-based products as labelled.

“Effective May 11, 2020, new label directions will apply to all products formulated with chlorothalonil, reflecting the required changes associated with the re-evaluation decision,” says Chris Davison, head of corporate affairs with Syngenta Canada.

“The PMRA are publishing new labels prior to May 11, 2020 and will be affixed to products that growers purchase for use in the 2020 season and beyond.”

Van Dyk published a guide on the changes to the Bravo Zn label. It can be found on the ONVegetable website.

About the author

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Jennifer lives on a farm in Cayuga, Ontario and has a lot of experience in the many aspects of agriculture.

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