“2023 Agricultural Pests to Watch Out For: Insects, Diseases, and Weeds Threatening Farmers”

Ravenous butterflies at the gates of Quebec, a “super” fungus attacking strawberry plants and swarms of aphids carrying a devastating virus: not a year goes by without its share of new threats for farmers. Here is an overview of the pests to watch out for in 2023.

European cherry fly

The biggest pest of cherry trees in Europe is now on this side of the Atlantic. “We found a few specimens around Montreal and in Ontario on wild honeysuckle plants on which it can make its life cycle,” says Olivier Morin, survey biologist for the Canadian Food Inspection Agency (CFIA).

Its larvae damage the fruits by feeding on the pulp, which can lead to the total loss of the harvest, without intervention. The biologist recommends that owners of cherry orchards monitor its presence. The insect is recognizable by its transparent wings spotted with black and its thorax marked with a yellow dot. If for the moment, no specific product is registered with us for its control, other insecticides against fruit flies are proving effective.

A butterfly native to Asia, the box tree moth has been causing a lot of damage to nurseries in Europe for the past fifteen years. Its caterpillar attacks boxwood, an ornamental plant appreciated by gardeners. The larva defoliates the shrub before attacking the bark.

The box tree moth was detected for the first time in Canada in 2018, in the suburbs of Toronto, but Quebec seems to have been spared so far. “Given its presence in Ontario, we can no longer export boxwood to the United States. However, if we manage to demonstrate the absence of this species in Quebec, that would give an argument in favor of the partial opening of the border,” argues Olivier Morin. The CFIA is also looking for nurseries or individuals who own boxwood in order to collect information for this purpose.

Dreaded for several years, the spotted fulgore continues its progression towards the North. This polyphagous butterfly, capable of wreaking havoc on a hundred plant species, was seen last April a few kilometers from the Canadian border in Buffalo and Detroit.

In the fall of 2022, the CFIA found dead adult fulgoras in products imported from the United States. “All it takes is for a mass of eggs on a product to cross the border and hatch here for us to find ourselves with this pest,” says Olivier Morin. The eggs of the fulgore can look like a waxy powder or dried mud that will be stuck to rock or wood.

“Various research on its behavior in North America has recently shown that its resistance to cold climatic conditions is greater than assumed, so southern Quebec is potentially at risk,” adds Jean-Philippe Légaré, biologist and entomologist at the Laboratory. of expertise and diagnosis in phytoprotection of the MAPAQ.

Cucumber mosaic virus

The year 2022 was marked by significant activity of this virus in eight regions of Quebec, mainly among cucurbit producers. “We believe that the soybean aphid is the vector of the virus, because there has been a correlation between the resurgence of this disease and a significant activity of this pest”, indicates Jean-Philippe Légaré. Although it does not feed on cucurbits, the soybean aphid does test bites on the plants to test the sap. Its presence, although very short, is nevertheless sufficient to infect crops.

Primarily found in the United States, this species occasionally produces a generation of winged individuals when its population density spikes. These are carried by the winds to other regions, as was the case last year. MAPAQ has set up a working group to monitor the situation and is funding a research project to recognize the warning signs of this problem.

This very virulent species, which particularly affects Fraser firs and balsam firs, causes crown rot, which prevents sap circulation and leads to tree decline. Already present in the United States and Europe, it was detected for the first time in Quebec in 2016. Further research revealed that it was present in several producers in the province. Various factors, such as soil that is too wet, could favor its presence.

Strawberry neopestalotiopse dieback

A pathogen already known to scientists, this disease caused significant damage to strawberry fields in Florida in 2018. Since then, it has spread to other regions, including Quebec in 2022 among several producers. “Is it a new strain or a different species? Hard to say, but it’s very virulent, because it leads to dieback of strawberries and causes considerable damage,” says Jean-Philippe Légaré.

Present in the American Midwest since the 1950s, this Asian grass was recently discovered in a few fields in western Quebec, where it competes with crops such as corn and soybeans. Its leaves, dark green and extremely hairy, have the texture of velvet. Its seeds tend to stick to machinery and can germinate until August. “It grows very well under the corn canopy. Glyphosate works, but its control is more difficult in organic management,” warns Olivier Morin.

Since its appearance in Quebec in 2017, tuberous amaranth has continued its meteoric rise in the province. In 2022, 33 new outbreaks were detected with single or multiple herbicide resistance. To fight against this species, the MAPAQ’s phytosanitary intervention plan is maintained in 2023 in order to support the producers affected. They can obtain up to $15,280 for biosecurity supervision.

This weed is mainly present in the fields of field crops in direct seeding. The first two cases of glyphosate resistance were confirmed in Montérégie-Ouest in 2021. And the following year, there were 15 cases distributed in Montérégie, Estrie and Lanaudière. “As its seeds are disseminated by the wind, they can travel several kilometers from one year to another”, specifies Jean-Philippe Légaré.

A first case of resistance to group 14 herbicides was recorded in Quebec in 2021 for this weed, which is common in annual crops. Subsequent screening activities made it possible to detect 11 resistant populations in the Laurentians, Lanaudière, Centre-du-Québec and Montérégie, among which 8 cases of resistance to group 2 were counted.

In the presence of a possible case of resistance to herbicides or an invasive species, agricultural producers are invited to contact the CFIA or the Laboratory of Expertise and Diagnosis in Phytoprotection (LEDP) of MAPAQ without delay.