Using Beleaf (flonicamid) as a drench: benefits and (potential) drawbacks.

gi_0_beleafGiven that it’s the season for pest problems like aphids on spring crops, I’d like to remind everyone of an important new pest management tool we have at our disposal.

Thanks to the hard work of Cary Gates at Flowers Canada Growers, and OMAFRA’s Jim Chaput, Beleaf (flonicamid) can now be used as a drench on greenhouse-grown ornamentals and cut flowers.

Read on for more details regarding the expanded label and potential phytoxicity issues.

Aphids on Calibrachoa –  a yearly occurrence.

The Product:

Beleaf (flonicamid) is registered for use on a variety of “sucking” greenhouse pests, but is definitely one of our most effective pesticides for aphids. Beleaf drenches can also help control greenhouse whitefly.  An added bonus is that it is compatible with most natural enemies used in greenhouses, meaning it’s unlikely to disrupt your biocontrol program (unlike neonic-based aphid products).

Why drench?

For spring bedding crops like Calibrachoa, which are pretty much guaranteed to get aphids, a single drench application of Beleaf when aphids first appear is likely to be sufficient for control until sale.  My tests indicate ca. 4-5 weeks of control, although this may vary. This way, repeated foliar applications – and potential resistance issues – can be avoided.

Further, while Beleaf has shown to be moderately hard on Aphidius and whitefly parasitoids when applied as a spray, it is likely far more compatible with these natural enemies when drenched, since they won’t come in contact with the product directly.

Drawbacks: Potential Phytotoxicity

Phytotoxicity on pansy from foliar application of Beleaf; photo courtesy of Dan Gilrein, Cornell Cooperative Extension.

As a foliar spray, Beleaf has demonstrated very little phytotoxicity – only certain pansy varieties have exhibited issues.

In the U.S. (where the drench has been on the label longer), no phyto issues from drenching with Beleaf have been reported.  However, phytotoxicity has been observed on some varieties of potted Chrysanthemums with drenching here in Ontario.  Varieties included Chesapeake, Sonoma and others.

Edge burn on mum leaves has been observed both at the full label drench rate AND at the half rate.   This needs to be officially reproduced, of course.  But until then – as with any new pesticide or application method – it’s a good idea to test a small patch of plants (at least 10/ variety) for negative reactions before a full application to your crop.  Note that damage can take almost a week to show up.

mum burn closeup
Leaf edge burn on chrysanthemum after a drench application of Beleaf at the full label rate. Symptoms were less severe, but still present, at the half rate.

Drench Rate:

The expanded label is available from the PMRA website here (click on the registration number, not the product name).  The new, approved drench rate for Beleaf in ornamental crops is 300 g/ha.  This works out to 0.2 g/L – 0.3 g/L based on an estimated planting density of 2.4 plants per sq. meter – but growers should make their own calculations based on their planting density.  

Beleaf drenches can be applied by hand or through drip irrigation.

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