Canadian producers join forces to save mancozeb fungicide
As of Feb. 5, 2019, 250 Canadian potato growers have participated in the Canadian Potato Council’s survey on mancozeb use, which will be submitted to the Pest Management Regulatory Agency (PMRA) to assist with the re-evaluation of the fungicide.
The proposed final re-evaluation decision for mancozeb, which suggests cancelling all uses of mancozeb except on tobacco due to unacceptable risks to human health and the environment, was published on Oct. 5, 2018, with a three-month consultation period. The Canadian Horticultural Council and the Canadian Potato Council were granted an additional 60-day period after the consultation deadline to gather more information on how growers use mancozeb for horticultural crops, including potatoes.
The council released a survey that Canadian growers could complete online or by hard copy to gather more information during this period. The purpose of the survey is to gather grower provided data that is “highly representative of how mancozeb is used in potato production overall across Canada and within each province.”
“Specifically, mancozeb use rates, number of applications, the use of aerial application under irrigated and non-irrigated potato production and the effectiveness of chemical and non-chemical alternative controls will be determined,” explained David Jones, manager of potato industry coordination with the Canadian Potato Council.
As of Jan. 25, 2019 , only 16 of 135 total survey responses were from Manitoba. During Manitoba Potato Production Days in Brandon, producers, especially from the province and Alberta, were encouraged to participate in the survey to include how they use mancozeb so the PMRA could make a nuanced decision.
In the Prairie provinces, producers often use aerial applications for fungicides because of the nature of the landscape and the lower population compared to Eastern Canada. “But Manitoba has higher humidity, somewhat similar to some of the eastern provinces, so we’ve got a situation where we have a lot of fungicide applications due to our climate, but we also do those by air because of our topography,” said Darin Gibson, president and research agronomist at Gaia Consulting and presenter at Manitoba Potato Production Days.
The grower survey sought to include the variety of ways producers use the fungicide so that PMRA’s decision would be reflective of the fungicide’s use in Canada. “[Aerial applications] will be considered differently and I’m not sure how that affects the final outcome, but it’s important that PMRA has the best information possible about how these products are used across the country, otherwise they make assumptions about the worst case scenario,” Gibson said.
“[The survey’s] highly representative data will provide quantitative information that PMRA can use to verify or correct assumptions that they have previously used in their assessment of risk associated with mancozeb use in potatoes,” Jones added. “The desired outcome is that the collected data will contribute to revised risk assessments that are favourable to the continued use of mancozeb in potatoes.”
The proposed re-evaluation decision removed the original exception that allowed for foliar application of mancozeb on potatoes and will have a great impact on potato growers.
Currently, mancozeb is one of the most economical broad-spectrum fungicides for early and late blight. Not only is the price point attractive, but because it is a multi-site fungicide, there is a low risk of diseases developing resistance to mancozeb.
“One of the problems is when you lose some of these products to regulatory issues, you end up depending on some of these single-site fungicides, which have a much higher risk of resistance,” Gibson said.
Currently, multi-site fungicides, like mancozeb, chlorothalonil, or metiram, are the base for any potato fungicide program because there’s little risk of diseases developing resistance to these fungicides. Gibson explained that if mancozeb is removed from the growers’ toolbox, growers would have to switch to single-site products, such as either an early blight product or a late blight product. The cost of production will increase because growers will have to tank mix two products; each of those products being more expensive than mancozeb.
Mancozeb is not banned in the European Union or in the United States, having undergone its own re-evaluations in those countries in 2018 and 2005 respectively. Gibson said he’s cautiously optimistic. “It’s going to end up in somewhat of a compromise where it’ll be maybe three to five applications, hopefully more, but I’m optimistic that it’s not going to end up at zero.”
The mancozeb use survey is available until Feb. 8, with anything submitted on Feb. 8 being accepted.
Since the low Prairie producers response numbers reported at the end of January, Jones said growers organizations in Manitoba and Alberta (KPPA, Peak, PGA) have made good effort to remind growers directly about the importance of participating in the Council’s survey. “The response from growers in Alberta and Manitoba has been excellent, representing about a third of the total responses received to date. The response rate is similar to the percentage of planted acres in those two provinces as a percentage of the total Canadian acres planted. This would indicate that the survey responses are highly indicative of potato production in Alberta and Manitoba,” Jones said.
“It’s an important issue for Manitoba growers and it’s just one of the important tools that growers have for protecting their potato crop and if they were to lose that one, they’ll still be able to grow potatoes, but it’s going to be more difficult and more expensive,” Gibson said. “So it’s really important that growers get their information to the Hort Council so that can be passed on to PMRA, so they can hopefully keep an important tool for their production.”
The survey is available online, or by hard copy that could be submitted via email or fax. To complete the survey, visit www.surveymonkey.com/r/TWW76JJ.