Pest Report: June 2, 2023

We are in the thick of some hot/dry weather, that’s for sure.

With those conditions in mind, keep your eyes peeled for building populations of mites, leafhoppers, and powdery mildew (among other things!) these pests can thrive in hot dry conditions.

Most regions of Ontario are nearing or already in the 150-200 GDD range. Some parts of SW Ontario have already reached the 200 GDD mark (base 10). Based on your regional GDD calculations, OMAFRA Publication 841 has tables for each of the ranges to help inform your scouting and management of pests in the nursery and landscape: Click here to view the PDF.

Potato Leafhoppers : they are here!

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Funding Opportunity: Invasive Species Action Fund

The Invasive Species Centre has launched a funding opportunity for projects and the deadline to apply is June 7, 2023.

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Directive Posted for box tree moth: D-22-04

For Ontario nurseries that grow and ship boxwood outside of Ontario, D-22-04: Box tree moth (Cydalima perspectalis) – domestic and import phytosanitary requirements, has now been posted.

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Pest Report : May Long Weekend!

Happy May long weekend to everyone! What a wonderful (and busy) time of year. This week I’ve been appreciating all the fantastic blooms in the landscape: have we ever had a bloom this long and beautiful? Not that I can remember!

Right now we’ve just about reached full bloom of Syringa vulgaris and late bloom of cercis canadensis in a number of regions. This indicates that most regions of Southern Ontario are entering the window of 100–150 GDD, Base 10°C.

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Risk of Frost this Week – Plan Now!

This article was adapted from an article by Sean Westerveld, OMAFRA Ginseng and Herb Specialist out of Simcoe with additions from a 2015 article from Jennifer Llewellyn, former OMAFRA Nursery and Landscape Specialist

Although the weather forecasts generally still show low temperatures above freezing in the evenings this week, the risk of frost especially Wednesday night is relatively high. This is because of the following:

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May 12th – Nursery Pest Report

Happy spring everyone and welcome to the first pest report for 2023.

We had a damp start to May that’s for sure, but the plants sure are loving the sun and heat from this week.

After this weeks warm temperatures, most of Southern Ontario is now in or entering the 55–100 GDD window (Base 10°C). Acer saccharinum are leafing out, Cercis canadensis is just starting to bloom and Magnolia’s are showing off those beautiful flowers!

With those phenological indicators in mind, here are some key pests to be aware of during this time and some notes about what we’ve been seeing in the field.

Aphids, Aphids, everywhere!… But also lots of beneficials.

  • Lots of aphids were encountered this week during scouting, especially on plants in the Rosaceae family.
  • BUT lots of beneficials were also found this week, one patch of Ribes Americanum had numerous adult lady beetles, syrphid fly eggs and larvae, and even some aphid mummies, recently parasitized by parasitic wasps.
  • In situations where an abundance of natural enemies are present and little to no plant damage is seen, no need to bring out the heavy duty insecticides (or maybe any at all for that matter). Beleaf is a great chemistry that is less toxic to beneficial insects. Insecticidal soap is always an option too. If you are seeing aphid populations build and are not so fortunate to come across so many natural enemies, a full list of registered insecticides by host plants is available in the tables in Publication 840.

Boxwood Bugs

This week, the nursery scout found an abundance of Boxwood leafminer larvae. Larvae are developing inside leaves (in those orangey spots) and so a translaminar product like Avid or a growth regulator like Citation are great products to use to target this stage of the pest before they pupate and exit the leaves.

In the landscape, Box tree moth larvae have emerged from their hibernariums and will be actively feeding on leaves. As they begin to feed and grow, the window to treat with Bt products such as Dipel, BioProtec Plus and XenTari, is starting. Note that Bt can be used in a landscape setting. At a nursery operation, you also have the option of using DeltaGard (deltamethrin).

The scout has not found any BTM larvae at any nurseries; everyone keep up the amazing work and make sure to get those box tree moth traps up ASAP if you haven’t already. More info on BTM resources was covered in an early blog post here: BTM Training and Resources

For nurseries in Ontario that produce boxwood, it is strongly recommended that you have pest modules in place to prevent box tree moth at your operation. For those nurseries that produce boxwood and ship outside of Ontario, the new directive that is anticipated to be released by CFIA is expected to require an approved pest module to be in place. I encourage you to discuss this with your local CFIA office if you have not yet.

While on the topic of Box Tree moth, CNLA and the CFIA recently released this awesome infographic. Feel free to download and share to your clients or customers!

Where the heck are the spongy moth?  

Have you seen spongy moth yet this spring? … me neither! Any egg masses the scout and I have found have all been from last year and finding new egg masses has been like searching for a needle in a haystack.

So what’s the deal? Well, maybe you’ve heard about the population collapse due increased natural predators. If you’re looking for some more information, there is a great article that talks about two of the diseases that help to control the populations after large outbreaks (nucleopolyhedrosis virus, or NPV, and a fungus called Entomophaga maimaiga). Click here for the article.

While spongy moth (the insect formerly known as gypsy moth) are not completely gone, most regions will see decreased activity this year. Continue to scout for spongy moth egg masses and emergence as there may still be hotspots in certain regions, but nothing like the population booms we saw over the last few years. With first bloom of Cercis canadensis, eggs should be hatching about now if they are present in your area.

Protect new leafy growth from disease

After the week of rain we had, the scout and I were seeing a lot symptoms of bacterial spots caused by Pseudomonas Syringae, especially on Syringa and Forsythia. Copper can be applied at 7-10 day intervals to help with bacterial issues. Leaf wetness is a major factor in disease development. Ensure plants are adequately spaced for optimal drying and avoid irrigation late in the day.

Extended rains brought about a flush of Gymnosporangium Rusts. Numerous telial horns were seen on Juniperus hosts. These swollen orange coloured jelly alien looking structures on branches release spores that infect and cause Rust disease on Malus, Pyrus, Quine, Amelanchier, and Crataegus. Prune out any galls after they have dried out to reduce infection to deciduous hosts. When the telial horns are sporulating, protect tender foliage with fungicides such as Daconil, Manzate, Nova, or Pristine.

Other things we are monitoring:

Potato Leafhoppers: The nursery scout has not found any leafhoppers yet this year. A pest report from University of Maryland Extension that just came into my inbox said they are just starting to see potato leafhoppers in their area that are moving up from the south. So it’s just a matter of time!

Spotted Lanternfly: Continue to keep your eyes peeled for spotted lanternfly! To date, NO live lifestages of SLF have been detected in Ontario. Growers importing plants from regions in the US where SLF is known to occur are encouraged to thoroughly inspect all parts of shipments upon arrival, before you integrate into your own plant stock. SLF egg masses have begun to hatch in some areas of the US so be sure to look out for both egg masses and 1st instar nymphs.

For more information on additional pests to monitor for from late April to Mid May, Refer to Table 2-6 in Publication 841, available at this link:

 Publication 841, Guide to Nursery and Landscape Plant Production and IPM (

Have questions or comments about anything in this post? Get in touch with me by emailing

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Japanese Beetle Control 2023: Changes to Allowable Pesticides and Updates to Infographic

Original post by S. Jandricic, Greenhouse Specialist OMAFRA on the blog

It will soon be that time of year again, when Japanese beetle (JB) adults begin to fly! However, there have been some changes to acceptable control products for JB that growers need to be aware of in order to be in compliance with certification programs for this pest.

This post highlights changes to treatments and also provides an updated infographic for JB control for those exporting to non-JB areas (both domestically and to the United States).

Infographic developed by S. Jandricic in collaboration with the CFIA. Only applicable to Ontario crops.

Step 1: Do You Need to Treat For JB at All?

As always, you want to start with the decision tree (pictured below) to decide whether you even need to spray at all. If your plants have been grown indoors during critical periods, or you’re not shipping to areas that restrict Japanese beetle (i.e. Category 1 and 2 provinces/states), then you might not have to.

Decision tree titled "Do I need to apply pesticides for Japanese Beetle Control before shipping?" which includes a number of yes and no questions and prompts.

We’ve made some changes this year to make the decision tree a little more clear, so be sure to download the most recent version at the bottom of this post.

In addition, we’ve also added a summary table of which conditions/programs you must fall under to make your product eligible for domestic shipment out of Ontario, as well any requirements/exceptions (for example, root ball size).

Further information on shipping requirements to the U.S. can be found under Section 6.1 of the D-96-15 Phytosanitary Requirements.

Step 2: Pesticide Choice and Timing

Now that you’ve figure that you DO need to use chemical controls for JB, the next question is WHAT do I apply and WHEN?  As there are only 3 products registered for JB certification programs in Ontario, the “what” part is easy (see the infographic, below).

However, some important changes have been made:

  • 1. Intercept (imidacloprid) is now only allowed for JB control on NON-FLOWERING plants. Therefore, most tree and shrub products can still use imidacloprid as a preventative treatment before shipping. However, growers shipping a crop like potted garden mums Category 1 or 2 provinces / states will have to use Acelepryn (chlorantraniliprole) instead.
  • 2. Products containing chlorpyrifos (Lorsban, Dursban) will no longer be allowed after December of this year. Although these were allowed under the program as a curative treatment for many years, this active ingredient is being phased out for most crops by the PMRA.

Important Reminders

There’s always at least 1 grower who misses this each year: please note that there are NO ACCEPTABLE PRODUCTS YOU CAN APPLY FOR JB CONTROL FROM MAY 15-JUNE 15. Why? Refer to this post on the timing of JB pupae and their susceptibility to pesticides.

Because there is a window where you can’t apply products, we strongly suggest growers shipping in late spring/early summer (i.e.May 1-July 15) make sure they get a curative application of Acelepryn on BEFORE MAY 15TH to avoid any issues with shipping to non-JB areas (both domestically and to the U.S.).

You can download a PDF of the whole 2023 JB infographic here. JB Infographic 2023.

If you have question about D-96-15 or the infographics above, do not hesitate to reach out to your local CFIA office or contact Dr. Sarah Jandricic, (GH Floriculture) or Cassie Russell, (Nursery/Landscape).

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Tank Mixing Update for Nurseries: Implications for Users of Pest Control Products

The following article was authored by J. Mosiondz (OMAFRA) with input from J. Deveau (OMAFRA)

Tank mixing, a practice commonly performed by growers across the agricultural spectrum, is an important practice used to reduce the number of sprayer passes per season, prevent resistance development, and to improve product performance.

Health Canada’s Pest Management Regulatory Agency (PMRA) recently announced clarifications to the tank mixing policy in a new guidance document on December 22nd, 2022, entitled “PMRA Guidance Document Tank Mix Labelling”.

Previously, products could be tank mixed if there were no restrictions on any of the partner labels. Under the updated policy, a tank mix can only be applied if the partner labels specifically allow tank mixing. This could appear on the label in one of two forms given below. Additional instructions such as mixing order, or instructions for performing compatibility testing such as the jar test method may also be included in these statements.

Option 1: The label specifically identifies permitted tank mix partners (e.g., “Product X may be tank mixed with products A, B, and C” …);


Option 2: The label includes a general tank mixing statement (see below) which permits tank mixing as long as both tank mix partner labels include the statement. Note that product labels may contain both the general tank mixing statement and a specific list of tank mix partners.

“This product may be tank mixed with (a fertilizer, a supplement, or with) registered pest control products, whose labels also allow tank mixing, provided the entirety of both labels, including Directions For Use, Precautions, Restrictions, Environmental Precautions, and Spray Buffer Zones are followed for each product. In cases where these requirements differ between the tank mix partner labels, the most restrictive label must be followed. Do not tank mix products containing the same active ingredient unless specifically listed on this label.
In some cases, tank mixing pest control products can result in reduced pesticide efficacy or increased host crop injury. The user should contact [insert registrant name] at [insert contact information] for information before applying any tank mix that is not specifically recommended on this label”.
PMRA’s generic tank mixing label statement as per Tank Mixing Labelling Guidance Document 2023.

It is also important to note that some product labels might have an exclusionary statement that specifically does not allow tank mixing (e.g., Do not mix or apply this product with any additive, pesticide or fertilizer except as specifically recommended on this label). If a product’s label contains this type of exclusionary statement, then it can only be tank mixed with the specific tank mix partners appearing on its label. To help guide interpretation of the label statements related to tank mixing, the guidance document includes a table to describe various scenarios and whether or not tank mixing would be allowed (see table 1 below).

Table 1: Permissibility of tank mixing based on various combinations of label statements related to tank mixing

Product X label saysProduct Y label saysCan I tank mix? (Y/N)
Nothing (silent on tank mixing)Nothing (silent on tank mixing)N
General tank mix statementNothing
(silent on tank mixing)
Nothing (silent on tank mixing)General tank mix statementN
General tank mix statementGeneral tank mix statementY
General tank mix statementTank mix with Product XY
Tank mix with Product YGeneral tank mix statementY
Tank mix with Product YNothing (silent on tank mixing)Y
Nothing (silent on tank mixing)Tank mix with Product XY
Tank mix with Product YTank mix with Product XY
Tank mix with Product YExclusionary statement (and label does not include a specific Product X tank mix)N*
Exclusionary statement (and label does not include a specific Product Y tank mix)Tank mix with Product XN*
*There may be registered labels that have tank mix scenarios like this. Note that this is not allowed for new tank mix label amendments. Further, any product labels that have tank mix scenarios like this must be amended to alleviate the contradictory scenario. To do this, using the last scenario in Table 1 as an example, one of the following must occur: 1) remove the Product X tank mix from the Product Y label, 2) remove the exclusionary statement from the Product X label, or 3) add a specific tank mix for Product Y on the Product X label. Source: PMRA Guidance Document Tank Mix Labelling 2023

Registrants are required to update their labels to align with these changes within two years of the publication date of the guidance document (i.e., by December 22, 2024). Likewise, according to a March 17, 2023, update to the guidance document, sprayer operators can continue their current tank mix practices during the two-year transitional period. On December 22, 2024, the PMRA policy will be in full effect; All practices, labels, marketing materials and educational materials must then be consistent with the new policy.

For growers, and other users of pest control products, this effectively means they may continue to tank mix as previously done for the 2023 and 2024 field seasons. However, when ordering and purchasing product in late fall 2024 and winter 2024-2025, users will need to ensure that desired tank mix partner labels permit tank mixing with each other to ensure their pest control product sprays applied in 2025 comply with the new guidelines. Parties affected by this new policy change are encouraged to review the guidance document in its entirety for a full explanation and further detail on these changes. For any outstanding questions you may have regarding these new guidelines after reviewing the guidance document, please contact the PMRA Info Service at Further information on tank mixing practices can also be found on the Sprayers101 website.

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Box Tree Moth: 2023 Training & Resources

Too busy to catch the last two Box Tree Moth Webinars? You’re in luck! Both were recorded and available to watch below.

First up, we have a short refresher video on basics of BTM biology, how to monitor for this pest, pheromone traps, and what’s currently registered for control of BTM.

Youtube video of scout training for box tree moth for 2023. In this webinar, Abbie Wiesner (MSc Candidate at the University of Guelph) reviews basic biology of Box Tree Moth and how to scout for this pest. Cassie Russell (Nursery and Landscape Specialist with OMAFRA) covers setting up pheromone traps and what chemical management tools are available as of April 2023 for growers.

Next, we have a link to the THRIVE webinar on the Basics of Box Tree Moth with Ontario’s own Dr. Jeanine West. You can watch that webinar (along with others) by clicking the photo below or visiting the following URL:

Image with the text "Horticultural Research Institute: tHRIve web series"

Additional Resources for BTM:

Here are some other helpful resources and information as we get into BTM monitoring timing for Ontario. A reminder that May is coming up quickly. Pheromone traps for Box Tree Moth should be put up the first week of May.

How to Set up a UniTrap for BTM :

Youtube video of how to set up a Unitrap with 1 month box tree moth lures. This video is available at the following URL:

Jen Llewellyn’s in-depth presentation on BTM (from 2019):

Youtube video of 2019 Box Tree Moth webinar given by Jen Llewellyn. This video is also available at the following URL:

Ontario BMPs for box tree moth (updated March 2023):
Click Here for the latest version of the BMPs posted by Landscape Ontario. Also available at this URL:

Update for Producers:

The CFIA is currently working on a domestic movement program in follow-up to the publication of their Risk Management Document 22-02 “Pest risk management decision for the regulation of Cydalima perspectalis in Canada” Click here for a link to the document. Also available at this URL:

If you haven’t already, growers are strongly encouraged to implement and be following a pest module for box tree moth.

Growers are encouraged to visit the Box Tree Moth Certification Program through clean plants which has a pest module for BTM, a companion document to help growers to fill out the module, BMPs and everything else needed to become BTM clean plants certified.

Links to the Clean Plants BTM Certification Program can be found at this URL:

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Upcoming Pest Webinars for Nurseries

With the season starting to ramp up, there are two upcoming (and free!) webinars that I hope will be helpful to any nursery staff, IPM managers, and others in the green industry. Both webinars are meant to serve as a training tool for staff to help scout, monitor, prevent and correctly identify two regulated pests in Ontario: Spotted Lanternfly and Box Tree Moth. See below for information on these two upcoming webinars. Hope to see you there!

Read more: Upcoming Pest Webinars for Nurseries

On March 29, 2023 there will be a webinar hosted by CNLA on Spotted Lanternfly

Topic: Spotted Lanternfly: Monitoring & Identification Training for Nursery Staff

When: Mar 29, 2023 1:00 PM (Eastern Time)

Description: Join Cassie Russell, OMAFRA Nursery and Landscape Specialist for this one-hour training webinar for you and your IPM staff to get the latest monitoring and identification best management practices for nurseries. Jamie Aalbers, CNLA Growers Sector Specialist will also provide a short update on the current regulations for SLF in North America and CNLA’s work on developing a Clean Plants SLF certification program.

You must register in advance for this webinar by clicking the following link:

After registering, you will receive a confirmation email containing information about joining the webinar.

The following week, OMAFRA will be hosting a webinar on monitoring and identifying Box Tree Moth.

Topic: Box Tree Moth: 2023 Training Webinar

When: Apr 6, 2023 11:00 AM (Eastern Time)

Description: In this webinar, Abbie Wiesner (MSc Candidate at the University of Guelph) will review basic biology of Box Tree Moth and how to scout for it at your nursery. Abbie will also review setting up pheromone traps and will be available to answer any questions for staff getting prepared to scout for this pest for the 2023 season. Cassie Russell (Nursery and Landscape Specialist with OMAFRA) and Jeanine West (Grower Technical Analyst with LO) will also be available to answer questions related to scouting and management of Box Tree Moth at nurseries.

You must register in advance for this webinar by clicking the following link:

After registering, you will receive a confirmation email containing information about joining the meeting.

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