|Honey bee in white clover|
Many of you are no doubt following the news about bee decline in the US and worldwide. Due to concerns about neonicotinoids in particular, the US EPA is making changes to the labels of these products.
Many growers are using Safari (dinotefuran), a neonicotinoid, for the control of elongate hemlock scale in Fraser fir Christmas trees. This product has proven to be the most effective at controlling scale in western North Carolina. Safari can be sprayed on the foliage or it can be applied as a trunk application. Both have proven effective.
The previous label of Safari indicated that plants shouldn't be sprayed if bees are visiting the treated area. This allowed the product to be applied of an evening or at night when bees weren't active.
The new Safari label which came out in 2014, is far more restrictive. The label now states that this product is "toxic to bees exposed to residue for more than 38 hours following treatment. Do not apply this product to blooming, pollen-shedding or nectar-producing parts of plants if bees may forage on the plants during this time period." The label also indicates it can't be applied "while bees are foraging" or "to plants that are flowering. Only apply after all flower petals have fallen off."
In other words -- no flowers period.
So what's a grower to do? Ground covers in Christmas trees are an integral part of integrated pest management. Besides controlling erosion and making the soil cooler so tree roots are closer to the surface, ground covers keep problem weeds from coming into a field and they are habitat for natural predators such as lady beetles, hover flies and lacewings.
In 2013, Jeff Owen conducted several demonstrations to find ways to keep good ground covers while getting rid of flowers and therefore bees. What he found was that our typical chemical mowing with Roundup will burn back flowers in ground covers including white clover within one to two weeks depending on the weather. Therefore, it's important when applying Safari, to time applications after a herbicide treatment. It's also important to scout before making an application to see if bees are visiting the area any further.
Protecting bees from pesticides is important, but flowering ground covers are also important to provide forage for bees as well for natural predators as well. With a little forethought, Fraser fir Christmas tree growers can create a win-win situation for themselves and pollinators.