TAKE 2: Updates on Fungus Gnat Control in Greenhouse Ornamentals 2024

There were some technical issues with the blog post going out over email today. Let’s try this again…

Fungus gnats and shoreflies will always be a nuisance in greenhouse crops and, at high levels, potentially damage roots and transmit certain plant pathogens. Recently, key pesticides for these pest have been lost, either through de-registration or via production decisions from manufacturers. Read on to see options for controlling fungus gnats in greenhouse crops.

Insecticides for Fungus Gnats and Shoreflies

A shorefly at rest in an ornamental crop. Photo by S. Jandricic, OMAFA.

Previous products available for fungus gnats and shoreflies in Canada included Citation (cyromazine), Dimilin (diflubenzuron) and Vectobac (BT israelensis).

Citation was no longer allowed for use on cut flowers in Canada in 2021 and Citation fell out of production in 2023. Similarly, Vectobac and Dimilin are no longer being produced by chemical manufacturers as of 2023/2024. There is little to no inventory of any of these products at pesticide suppliers in Ontario.

Currently, there are only 2 available insecticides for fungus gnats (and by extension, shoreflies, since they tend to co-occur).

The first is a “dupe” for Citation, called Cyrus. (Shout out to Hailey Ashbee at Royal Brinkman for letting me know about this one!). It’s registered for use in greenhouse crops and the label can be found here. The second option is Distance (pyriproxifen). This is an IRAC 7 insect growth regulator, and is highly effective against eggs and larvae of these pests.

As a reminder, links to currently registered and available products for greenhouse pests in Canada can be found on Ontario’s Crop Protection Hub, under the Greenhouse Ornamentals crop module (I’ll be adding Cyrus to Crop Hub shortly!) The Greenhouse Vegetable module is also up, but still under construction. It will be fully populated in Spring 2025

An example of a pest search (aphids) within the greenhouse ornamentals module in Ontario’s Crop Protection Hub.

Biological Control of Fungus gnats and Shoreflies

Unfortunately, Distance and Cyrus can be somewhat hard on immatures of beneficial insects, including Dalotia coriaria. Further, having only 2 chemicals available can increase the risk of pesticide resistance in the long term. So, if you’re not already familiar with them, now would be the time to get to know which biocontrol agents are most effective for fungus gnats and shoreflies, so you can work them into your production system this spring.

As a place to start, here is a quick reference list of what bios are available for which pests:

E3299_COMMERCIALLY_AVAILABLE_BIOLOGICAL_2024Download

Additionally, here’s some further reading that can get you started in the right direction:



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