T’is poinsettia sticking time of year once again , and the query always comes down to the same matter : do I use chemicals to controlBemisiawhiteflyand Bob Hope it worksthisyear ? Or do Iswitch to biologic control ? Here we show somehead to manoeuver comparisonsthat can help you decide .
Pesticides Vs. Bios: Efficacy
BecauseBemisiawhiteflies originate on cutting , and all commercial-grade producer presently trust on pesticide plan for direction , yourwhitefly will belike have been exposed to multiple applications of several group of pesticidesbefore they enter your greenhouse .
Depending on the suit of chemical chosen at the producer end , this means thatin SOME age ( for example 2017 , Fig . 1 ) , we will still have effective chemicals to choose from in Canada . But , in other years(e.g . 2018 , Fig . 2 ) we wo n’t have ANY .
This is because overexposure to chemical can driveBemisiapopulations to be in the first place pen of the“Q ” biotype .
Fig. 1. in 2017, chemicals were as effective as biological control using parastioids (with or without a predator) in a commercial greenhouse test (1 bay per treatment). Whitefly present on less than 15% of the crop is acceptable to most commercial buyers and is considered a successful program. Predatory mites by themselves were not effective.
Currently , the Q biotype looks to beresistant to all whitefly chemicals registered in Canada . This is based on grower trials ( below ) . This inlcudes Altus ( flupyradifurone ) , Beleaf ( flonicamid ) , Distance ( pyriproxifen ) , Dynomite ( pyridaben ) and Kontos ( spirotetremat).Read more about whitefly biotypes inthis article .
Overall , several years of grower examination demonstrates thatbiocontrol is the only logical coming .
Pesticides Vs. Bios: Economics
One matter growers are justly concerned about when it come to switch to biocontrol from pesticides is cost . Tweaked for the individual farm and pest pressing , biocontrol programs , reckon on company and merchandise , can crop from a nominative 3 cent ( CDN$ ) to around 12 cent per pot . It takes a bit of playing to specify what works for your special farm ( and poinsettia varieties grown ) for the low costs , which is why it can be proficient to lick with an independent consultant .
While it ’s reliable that chemical mastery programs for whitefly in poinsettia are flash – somewhere around 2 cents / pot in commercial visitation in Canada – this assume the pesticides will influence .
In years where whitefly populations come in on cut have grow substantial resistance , pesticide monetary value can skyrocket as multiple ( ineffective ) spray are made ( see Figure 2 ) . The result pesticide monetary value and crop losses ultimately end up being much higher than a biocontrol programme would have been .
Fig. 1. in 2017, chemicals were as effective as biological control using parastioids (with or without a predator) in a commercial greenhouse test (1 bay per treatment). Whitefly present on less than 15% of the crop is acceptable to most commercial buyers and is considered a successful program. Predatory mites by themselves were not effective.
And , as one cultivator put it,“costs are irrelevant if you ca n’t control the pesterer ” .
Which Bios to Use:
A successful biocontrol program swear on sleep with which bios to employ , and when to use them . Canadiangrowers are rule success using one of the three following programs . One thing all three have in common is the function ofmultiple lifelike foeman , to aim multiple life sentence stage of gratifying potato whitefly ( human body 3 ) .
Check back shortly for posts abouthow to monitor for whitefly and parasitismin your Mexican flameleaf craw , andknowing what to do if things hit vital levels .
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Figure 2. Multiple chemicals were applied against whitefly in 2018, and all failed. All 3 biocontrol programs tests (see below) were effective. Tests were conducted in the same commercial greenhouse as 2017.
Figure 2. Multiple biocontrol agents are often needed to control whitefly, which can drive up costs.
Fig. 4. Bemisia whitefly parasitized by Encarsia (left) and Eretmocerus (right).
