Pesticide Rotation Guide for Thrips parvispinus in Canadian Greenhouses

By Sarah Jandricic (OMAFA) and Judy Colley (Plant Products)

*A female (left) and male (right) Thrips parvispinus on a mandevilla flower.*

With the arrival of mandevilla, dipladenia and hibiscus cuttings, now is the time to start planning your management program for Thrips parvispinus. Unfortunately, it looks like this pest is here to stay in North America, and in the tropical plant industry at large.

In this post, we’ll focus on pesticide rotations to manage pesticide resistance, as well as a few tips and tricks to make sure your pesticides stay working.

Continue reading →

“How-to” Video of the Week: Plant Washes and Other Tools to Make Detecting Parvispinus Easier

*OMAFA Summer Student Avery Johnson demonstrating plant washes on-farm.*

In this week’s “how-to” video, we’ll explore using plant washes on-farm.

Plant washes are a simple but effective method to detect low levels of critical pests, such as Thrips parvispinus.

Once you’ve washed out your pests, we’ve also developed a quick “decision tree” to help you easily determine if you’re dealing with Thrips parvispinus or another thrips pest.

Keep reading to find the link to the video and additional resources.

Continue reading →

Potted Chrysanthemums 2024: Dips, Thrips and Threats

Every year at this time, growers start to think about strategies to minimizing western flower thrips on their chrysanthemum crops. This year, Thrips parvispinus is causing extra concern, given that chrysanthemum is one of its reported hosts.

Although there have been no reports yet of Parvispinus damaging chrysanthemums in North America, it’s still good to exercise a bit of caution. However, jumping the gun and spraying chemicals will likely just disrupt your biocontrol program for western flower thrips, leaving you with a bigger mess on your hands.

This post contains information on things you can do to put your mind at ease about all sorts of thrips this chrysanthemum season.

Continue reading →

Parvispinus on Poinsettias? It’s Possible.

Fig. 1. *Parvispinus feeding on a poinsettia leaf.*

Growers in Ontario continue to struggle with Thrips parvispinus on tropical crops like mandevilla, anthurium and schefflera. Unfortunately, reports out of Europe also indicate this invasive pest species can also attack poinsettia.

Read on for what you need to watch out for, and potential management strategies.

Continue reading →

In Case you Missed it: “A Pain in the Parvi” GrowON Webinar Recording (Plus, Another Thrips parvipsinus Webinar with GrowPro!)

In case you missed the GrowON webinar by myself and Judy Colley from Plant Products on Jan 29th, we’ve now uploaded to Youtube!

You can find it the ONFloriculture Youtube page, along with lots of other useful videos and webinars.

Are recorded webinars not your thing? Well, then you have two additional options!

Continue reading →

Trap Plants as a Tool Against Thrips parvispinus in Tropicals

*Sweet alyssum (Lobularia) as a trap plant for T. parvispinus.*

Thrips parvispinus has become a serious pest of tropical ornamental crops in North American since 2020. Due to the severity of the damage, IPM strategies are needed to complement chemical control until an effective and economical biocontrol program can be developed for this pest.

Mass trapping through traps, lures, or trap plants can be an effective strategy for thrips. We’ve already seen that mass trapping cards REALLY help with this pest (more on that, later). And, it seems that trap plants may also be an effective strategy when used properly in vegetative crops.

Read on for what we did and how to implement it on YOUR farm.

Continue reading →

Got Tropicals? How to Detect and Monitor for Thrips parvispinus.

*Figure 1.* Thrips parvispinus female. Photo by A. Summerfield, Vineland.

In a previous blog post, we talked about which pesticides can control Thrips parvispinus if you end up with an infestation from imported plant material.

But how do you figure out if this invasive pest is in your facility in the first place? And, if so, what’s the best way to monitor their populations?

After working with this pest for the last 1-2 years, researchers like myself have figured out which monitoring methods are most effective. This can help you identify the problem early, begin a management plan, and monitor the efficacy of your controls.

Continue reading →

Pesticides for Parvispinus: Results of an On-Farm Trial

*Female T. parvispinus (left) on a mandevilla flower; a smaller male (yellow, right) can also be seen.*

Although the invasive pest Thrips parvispinus continues to threaten tropical ornamental crops, the good news is that the sky isn’t falling. Producing crops like mandevilla, schefflera and hoya is still possible, at least in a closed greenhouse setting.

Although developing a reliable biological control program for this pest is probably a few years off, a suite of pesticides is available in the U.S. and Canada to successfully manage T. parvispinus.

This post covers these pesticides, their relative efficacy and demonstrates outcomes when used in an 8 month on-farm trial in mandevilla.

Continue reading →

Thrips parvispinus (“Pepper Thrips”): The Importance of Inspecting Plants and Dipping Cuttings from Florida

I’ve written about the tropical pest Thrips parvispinus, now being called “pepper thrips”, infesting certain tropical ornamentals in Canada before. But it appears this pest has become widespread in Florida.

As Ontario sources much of its plant material from Florida, it’s a good idea to exercise caution, even on non-tropical plants. The known host range of this pest is evolving, and thrips have the potential to hitch-hike on less-preferred plant hosts and spread to more preferred hosts in your greenhouse.

Read on for information on the situation in Florida and what you can do to help protect your greenhouse from this pest.

Continue reading →

Tropical Thrips Species Intercepted on Plant Material in Ontario: Be Aware – But Don’t Panic.

This post was co-written by A. Summerfield (Vineland Research and Innovation Centre) and S. Jandricic.

*Figure 1. Thrips parvispinus is generally dark coloured (though the head and thorax can be lighter than the abdomen), has bright red ocelli and clear patches at the top of its wings.*

Increases in global trade, along with decreased use of harsher broad-spectrum pesticides makes it easier for insect species to move around the world. Because of this, it is becoming more common to find unusual pests coming in on plant material. It’s important that we are prepared and know what to do when something like a new thrips species makes an appearance.

The tropical thrips species Thrips parvispinus has been popping up in various parts of the globe in recent years and was intercepted on plant material in two Ontario greenhouses in 2021/2022. Read on to learn what we know about this species and what you should do if you suspect you have them.

Continue reading →