Dips, Thrips and Threats – ONfloriculture

Yearly right now, growers begin to consider methods to minimizing western flower thrips on their chrysanthemum crops. This yr, Thrips parvispinus is inflicting additional concern, provided that chrysanthemum is one among its reported hosts.

Though there have been no experiences but of Parvispinus damaging chrysanthemums in North America, it’s nonetheless good to train a little bit of warning. Nevertheless, leaping the gun and spraying chemical substances will possible simply disrupt your biocontrol program for western flower thrips, leaving you with an even bigger mess in your fingers.

This publish accommodates data on issues you are able to do to place your thoughts relaxed about all kinds of thrips this chrysanthemum season.

Dips for Thrips

A lot of you studying this publish may be frightened about Thrips parvispinus this yr, as we get every little thing from tropicals and foliage crops, to chrysanthemum and gerbera cuttings, from Florida.

The excellent news is that reducing dips are a confirmed tactic in opposition to thrips pests in Canada and several other merchandise had been lately registered within the U.S. for this use. This method makes use of reduced-risk pesticides comparable to oils, soaps and microbial pesticides to successfully smother thrips when they’re briefly submerged in these merchandise, lowering incoming populations.

We all know this successfully reduces western flower thrips arriving on potted mum cuttings when used correctly and provides pure enemies time to construct up on crops and work extra successfully. This work on dips got here out of the Organic Crop Safety Lab on the Vineland Analysis and Innovation Centre.

Extra lately, Rose and her Senior Lab Technician, Ashley Summerfield, supplied data on the efficacy of reducing dips on Thrips parvispinus. Just like outcomes with different thrips species, their work confirmed that dips in BotaniGard WP or mineral oil decreased Thrips parvispinus on plant cuttings by round 70%.

Greatest Practices for Slicing Dips

We advocate that ALL growers start implementing dips for each potted and backyard mum cuttings coming in, particularly these coming from Florida. (Notice that oils are NOT really helpful for backyard mums because of phytotoxicity).  

Vineland and OMAFRA lately launched a collection of “How-To” movies on the subject of greenhouse IPM. Correct dipping method for cuttings is demonstrated right here:

By way of which merchandise to make use of, label registrations in Canada embody:

• BotaniGard WP: registered as a dip on all greenhouse ornamentals for whitefly. That is additionally efficient in opposition to thrips.
• Kopa cleaning soap: registered on all greenhouse ornamentals for whiteflies
• Panorama oil: registered on all greenhouse decorative crops for thrips and whitefly
• Suffoil-X: registered on all greenhouse ornamentals for thrips and whitefly

Dip registrations within the U.S. embody the next (from Michigan State Extension’s Greenhouse Insect Pest Administration Suggestions 2024):

Continued Monitoring and Pest Administration for Thrips

Though dips might help cut back incoming thrips, they aren’t a silver bullet to eliminate the issue. for those who’re involved about Parvispinus in your mums, you possibly can add weekly purposes of Lalguard M52 OD on the misting bench. This product is suitable with predatory mites for western flower thrips management, so it’s a sensible choice.

On-farm investigations by Plant Merchandise and OMAFRA have demonstrated M52 to be the best microbial product in opposition to Thrips parvispinus (up to now, in any case). Fortunately, M52 is simply as efficient in opposition to western flower thrips as Beauveria-based merchandise, so that you’d be killing two birds with one fungus. Notice that merchandise containing the fungi Metarhizium, like M52, are usually much less steady after opening than Beauveria, so it’s finest to make use of the bottle up instantly.

One other potential instrument is the is a second dip of rooted cuttings in M52 or Suffoil X earlier than potting, to additional cut back thrips in manufacturing. That is nonetheless within the analysis part, however on-farm trials final yr confirmed a discount of 50-70% of Thrips parvispinus on rooted mandevilla. (Notice, this has not but been examined on mums re: phytotoxicity).

Though it may be tempting to use typical pesticides for suspected Parvispinus in your mums (e.g. Success, Pylon, Avid), these merchandise will disrupt mite-based biocontrol applications for western flower thrips and spider mites for a lot of weeks. This needs to be averted except you’ve had an professional make a optimistic identification and might help you give you a administration plan. The one exception to this may be Rimon (Novaluron), often known as Pedestal within the U.S. Novaluron is efficient in opposition to Parvispinus larvae however can be usually gentle in opposition to predatory mites.

You’ll additionally wish to proceed monitoring the crop for any indicators of Parvispinus by way of the entire crop. Thrips issues typically take round 3-4 weeks to indicate up after sticking cuttings, as soon as populations construct up. You possibly can examine efficient methods for monitoring for this pest on this publish from 2023.

You possibly can additionally put just a few candy alyssum (Lobularia) crops out if in case you have any left over (or develop new ones from seed), as research by OMAFRA and Plant Merchandise have proven they’re a superb indicator plant for Thrips parvispinus.

The Backside Line

Keeping track of your mum crop, particularly when getting cuttings from areas the place Thrips parvispinus has change into endemic, is a good thought. Nevertheless, it’s essential to remember the fact that we’ve but to see this pest on this crop within the North East. That is true even when mums have been grown in greenhouse zones straight after a crop with Parvispinus (e.g. Mandevilla). I’ve additionally not heard experiences of Parvispinus inflicting injury on chrysanthemum from growers within the Southern U.S.

If you’re nonetheless involved about any dark-coloured thrips you may be discovering in your mum crops, keep tuned. Subsequent week we’ll put a publish up on methods to to detect low numbers of thrips within the crop and do a fast and soiled evaluation to be sure to’re not coping with Parvispinus.

Dr. Sarah Jandricic has been the Greenhouse Floriculture IPM Specialist for the Ontario Ministry of Agriculture, Meals and Rural Affairs (OMAFRA) since 2014. She has beforehand performed floriculture IPM analysis within the US (at Cornell College and North Carolina State) and spent two years as Director of Analysis at a personal IPM consulting firm.