Japanese beetles are in flight! WHAT and WHEN to spray.

The Japanese beetle season is upon us once again!  Adults were spotted this week in Southern Ontario.

Shipping outside Ontario or need to meet the requirements of the JB module for the Greenhouse Certification Program? Not sure what’s required?

This post contains a treatment “decision tree” and a JB product “cheat sheet” to help growers of greenhouse ornamentals.

JB as a “Greenhouse” Pest: Do I Need to Treat?

Japanese beetle are often thought of more as nursery crop or turf pests.  But the reality is Greenhouse-grown ornamentals are also susceptible if they get exposed to the outdoors when adult JB are around. Note that plants grown or kept briefly in a cravo are considered to have been “outside”.   Better safe than sorry is the mantra here.

So, if your plants have spent ANY time outside during the flight period of  JB (from June 15 until Sept 30), or have been in contact with plants that were, the CFIA needs you to spray if you’re planning on shipping outside of Ontario or need to meet the requirements of the JB module as part of the new Greenhouse Certification Program. See Section 5.1 of CFIA Directive 96-15 for more information on types of certifications.

Knowing WHAT to use:

This part is relatively simple, given that only THREE active ingredients are currently approved by the PMRA for Japanese beetle control in Canada.  These are (with links to their current labels):

• Chlorantraniliprole. The product Aceleyprn is registered for greenhouse use.
• Chlorpyrifos. Greenhouse products include Lorsban 4E or Dursban T
• Imidacloprid.  The registered product is Intercept  (though note it’s only registered for JB application, specifically, during the outdoor phase of ornamental production).

NO other active ingredients are allowed, as these are the only proven actives against this restricted pest.  Technically, there are some adulticides registered for adult JB beetle control on outdoor ornamentals (such as Sevin (carbaryl) and now, BeetleGone, a Bt product), which could be included as part of a general management program, but these are NOT part of an acceptable JB quarantine program.

Knowing WHEN to use it:

Right now, we are in the “prevention” strategy part of the plan for JB, so it’s time to use  chlorantraniliprole or imidacloprid (see more on why, below). To forge your JB plan for the rest of the year, here’s a chart outlining the timing for all JB products registered in Canada:

The WHY of it:

Different products are recommended at different times of year because of a variety of factors that affect their efficacy.  These include:

1. AVOIDING NON-SUSCEPTIBLE STAGES: Generally speaking, pesticides are less effective against immobile insect stages.  This is either because they aren’t ingesting any of the active ingredient or because they don’t have the right receptors. For JB, our registered, soil applied, pesticides have no effect against the pupal and egg stages.  Thus, for the window between May 15 and June 15, no pesticide will be effective, and you’ll just be wasting your 1 allowable application of chlorantraniliprole (Acelpryn) or imidacloprid (Intercept).
2. TARGETING OPTIMAL STAGES: Some pesticides are only effective on smaller larvae of JB, meaning they have a much smaller application window.  Imidacloprid, specifically, will not control the older, bigger larval stages of JB, so it must be applied when 1st instar larvae are present.
3. RESIDUAL TIMES OF PRODUCTS:  Because chlorpyrifos (Lorsban or Dursban) only persists in the soil or media for a relatively short time, it can only be applied curatively, close to shipping, to kill any larvae that might be present.  Alternatively, chlorantraniliprole (Acelepryn) or imidacloprid (Intercept) have long residual times, meaning that they can be applied preventively once JB adults start flying, and will  offer protection against any young JB larvae that hatch out in the soil.

Printable Resources:

Both the “JB Decision Flow Chart” and the “JB Control Timing Chart” are meant to be downloaded and printed (see files below) for easier reading.  These fit nicely onto a regular 8X11 page to decorate your office with and refer to regularly.

JB Spray Decision Tree and Control Timing Chart 2019_PDF VERSION

JB Spray Decision Tree and Control Timing Chart 2019_PPT VERSION

You can also find the most recent information regarding the Greenhouse-Grown Certification Program (GCP) here.  Directives specific to Japanese beetle phytosanitary requirements can be found here.  Dr. Jeanine West at Flowers Canada GOntario (jeanine@fco.ca) is a great resource for any questions surrounding the new GCP program.