Mancozeb, a group M fungicide, has been approved for continued use under the the Pest Control Products Act.
The pesticide re-evaluation was completed by the Pest Management Regulatory Agency (PMRA) and the announcement was made Nov. 19.
Why it matters: The elimination of Mancozeb would have been costly for farmers. The product has been used for numerous years and has proven beneficial against numerous diseases.
Mancozeb is a valuable tool for producers. It provides control over a broad spectrum of diseases for a large variety of crops and helps to reduce resistance. As well, it is a relatively inexpensive product.
“It can target both fungal and oomycete diseases. These are two separate classes of pathogens that cause diseases. It also attacks the pathogen in multiple ways so it’s really hard for pathogens to develop resistance,” says Katie Goldenhar, horticultural plant pathologist with OMAFRA. “(Mancozeb) can also protect and prolong some other medium to high risk fungicides that are prone to developing resistance.”
Although the product has been approved for continued use, there have been numerous changes from the previous product label.
Almost every crop has a reduction in the number of uses allowed per season, says Chris Duyvelshoff, crop protection advisor with Ontario Fruit and Vegetable Growers’ Association (OFVGA).
Application rates decreased, pre-havest interval increased
Several crops also have a reduction in the application rate. As well, a longer pre-harvest interval for crops has been applied and the restricted entry intervals have been increased.
The changes come into effect two years from the Nov. 19 decision date to allow time to change labels and have them approved.
“Growers who had previously purchased a large inventory have time to utilize the product before the (old) label is obsolete,” says Duyvelshoff.
In fall 2018, the PMRA proposed Mancozeb’s registration be cancelled for all crops except for use on tobacco transplants in greenhouses. This was due to concerns that the estimated residues from that use pattern would exceed the level of acceptability in food and drinking water.
“This caused quite a stir in the industry because Mancozeb is so foundational to a lot of disease control programs in horticulture,” says Duyvelshoff.
There was a lot of discussion among the PMRA, the registrants, and grower organizations to come up with a game plan for the proposed decision.
OFVGA consulted its membership on what could be tolerated in terms of reduced number of applications, reduced rates and longer re-entry intervals.
The data collected was brought to the PMRA and registrants, and the product was brought back under analysis.
“The companies we collaborated with are called registrants — the companies that own the registered products. In this case it was Corteva Agriscience and UPL Limited. Obviously it was successful because of the new outcome that kept a number of the applications on lots of crops,” says Duyvelshoff.
“It’s great that the review came out and there are so many uses for a lot of crops. There are going to be some challenges for some of the crops that did lose the complete use of Mancozeb or lost some applications. But I think overall it is positive because there are a lot of crops that (are allowed to continue) the use of Mancozeb,” says Goldenhar.