Carbaryl, used in brand name products Sevin, is the standard mountain pine beetle treatment and has been used in agriculture since the 1950s. However, permethrin, a new chemical found in Astro and other products has gained steam over the last decade because of its lower toxicity, easier clean-up, and near parity in effectiveness.
Here are some of the benefits and drawbacks of both.
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According to a research study published in the Sept. 2006 issue of Arboriculture and Urban Forestry, pyrethroid treatments (permethrin is a pyrethroid) “offer an excellent alternative to carbaryl.” The article also reiterates other research that found carbaryl to be the “most effective and environmentally safe product used to prevent bark beetle attacks on individual trees.”
Lodgepole pines and ponderosa pines were tested in the study, conducted during the 2004 and 2005 seasons.
“I prefer using permethrin (on pine beetle) for reasons of cost, safety, and efficacy, ” said Denver-based arborist George Biedenstein. “But carbaryl is proven over time and people are more comfortable with the chemicals they are used to. I have used Sevin (carbaryl) personally, for my vegetable for years.”
However, one only needs to consider the downsides of using carbaryl-based products to understand why HOA’s and government officials are looking for other solutions. Since it is a latex-based product, it can leave white spots that can stain decks, cars, and houses. Carbaryl has a higher rate of mammalian toxicity than other products on the market. Anecdotal evidence exists of birds “going into seizures” when exposed to it. Also, carbaryl is destructive to honey bees and beneficial insects.
But, permethrin is no cakewalk. It can be injurious to cats and birds. While in a different category of chemicals thought to be safer for the nervous system, less is known about the long-term effects.
So it’s important to look at the cumulative effect over several seasons. While permethrin has a lower labeled rate of application, you have to apply it every season. Many arborists use carbaryl because you only need to apply it once every other season, giving more flexibility.
One Victoria, BC-based arborist wrote, “The best bet is to go with carbaryl; in theory one ‘proper’ application of Sevin XLR+ should be good for two years. Spray the even-numbered trees one year and the odd-numbered the next. You can spray early or late in the day when the honey bees are in their hives and it is effective. ”
You may ask, why use either? Just like electricity, these chemicals can be safe and beneficial or harmful depending on how they’re used.
The proper use of chemical treatments is the only effective method of fighting the mountain pine beetle. Trained applicators know how to use these applications so they are safe and effective. Qualified applicators will not apply when it’s windy or near water, to prevent drift.
Think about it, what would you do if you were faced with losing 5, 10, or all the trees on your property or if it’s your job to keep roads free and clear from toppling trees?