If your Bucks County property is especially rich in trees and topiary – mature white pines, perhaps, or maybe spruce or fir trees – chances are better than average that you’ve already put a fair amount of time and money into maintaining your investment. So what could possibly be worse than watching your trees being literally destroyed from the top down?
Unfortunately, that’s an all-too-common occurrence for property owners in Bucks County and a number of other regions in Eastern Pennsylvania, where a devilish little pest known as the white pine weevil attacks and subsequently kills the tops of trees each year.
Read more about How to Control White Pine Weevil with Soil Injections
A tree that has been treated for Emerald Ash Borer (right) compared to one that has not.
The Emerald Ash Borer (EAB) has finally arrived in Southeastern Pennsylvania and that is leading to some tough and costly calls about preservation by local governments. The pest has been slowly making its way across the state and was first documented in our area in 2012. It had already been in the infected trees for two or three years at that point. The EAB has been found in area trees and parks (although it is believed to have not yet crossed the river into New Jersey). The invasive species is widely considered to be one of the most destructive forest pests ever to come to North America. In the end, the total costs to the country, particularly to states and municipalities, could total in the billions.
While many Ash trees in the Southeastern Pennsylvania may not yet be infected, it is only a matter of time. Unfortunately, Ash trees make up nearly 20 percent of the local tree population in Bucks County. While it can be devastating for homeowners to discover the pest, the costs for local governments can be exponentially more, simply due to the number of trees they must manage. Planning ahead can help blunt the impact of the EAB infestation and save your community money. Read more about Emerald Ash Borer Management an Issue for Municipalities
The white pine weevil, one of the most destructive pests of the eastern white pine in Pennsylvania, kills the tops of many different types of conifers. Although it attacks mostly pines, it can also be found in spruce and fir trees. Several generations of this pest can severely reduce the aesthetic value of their host.
White pine weevils spend the winter as adults in dropped needles under or near host trees. As days warm up in March or April they will fly or crawl to the leaders of suitable hosts. They begin feeding on the bark of terminal leaders. Mating occurs on the bark of the tree through most of June. A single female may lay 100 or more eggs in pits on the bark of the previous year’s leader. After hatching, grubs tunnel downward under the bark. Adult beetles emerge from late June to early September. After emergence, the beetles fly to other areas.
Between the feeding and the egg laying, the top 18-24″ of the leader is usually killed. Severe infestation may result in the loss of 2-3 years of growth. Glistening drops of resin oozing from holes in the leader are the first signs of attack, caused by adult weevils that are feeding before egg-laying. As the terminal is girdled, the new shoot of the current year’s growth withers and the tip bends over and turns brown. This stage of damage usually becomes noticeable in July. These infested leaders should be pruned at a point below the tunneling grubs, making sure to either burn or secure them in plastic trash bags and remove them from the property. If left on site the weevils may continue to develop in the prunings.
The standard treatment for pine weevil is to spray insecticides such as permethrin, bifenthrin or cyfluthrin at different intervals, but timing of these spray treatments is critical. The first application, to the terminal leader, as well as the lower trunk of the tree, must be done right before the adults begin feeding and laying eggs. A second spray treatment should be done a few of weeks later to protect the terminal leader. Other applications to the leader during midsummer are often necessary to manage this insect during outbreaks.
As an alternative, a single systemic soil injection of Imidacloprid can be applied in the fall to avoid multiple spray applications throughout the season. This allows adequate time for the chemical to be taken up to the terminal leaders of the tree. This method of control uses less active ingredient of chemical overall and has a lower environmental risk. It also has a reduced impact on natural enemies of the weevil.