What Trees Are At-Risk? SLF’s favorite host tree is the Tree of Heaven. Unfortunately, it also attacks many of trees that are most common in our landscapes. High-risk trees include: Maple, Oak, Walnut, Poplar, Willow, Birch, Ash, Linden, and Sycamore.
How Does SLF Damage Trees? SLF taps into trees like a straw and sucks out tree sap. Damage can range from oozing sap, wilting, leaf curling and even tree death.
Troubling Side Effects: Dripping excrement, stinging wasps and sour odor are often ugly consequences of SLF.
Swarms of SLF can feed on a single tree. The feeding produces so much “Honeydew” (aka excrement or droppings) that it looks like rain pouring through the tree. Honeydew coats everything under the tree, including cars, hardscapes, and decking. Once there, black, sooty mold grows on the Honeydew. The combination of Honeydew and black, sooty mold creates an unpleasantly sour stench. Even worse, the odor attracts stinging wasps (pictured).
SLF is not easy to control.Penn State warns that SLF is very mobile and management actions must be continuous to keep them off your property. As a property owner, you have the power to help stop this pest. Here are the actions you can take and the best timing:
Mechanical Control by Property Owner:
October-April: Check trees, understory plants and even under and sides of walls, cars, grills and lawn furniture for mud-like egg masses. To destroy, scrape off into a bag that contains rubbing alcohol or hand sanitizer. (Photo Credit: PA Dept. of Agriculture)
May-July: Band high risk trees with an adhesive trap to capture SLF Nymphs. Replace bands every two weeks. Caution: Bands may also trap other wildlife!
Host Reduction (Year-round): Kill Tree of Heaven with herbicides and then remove the dead trees if desired.
Chemical Control by PA Certified Applicator (July-Mid-November): Research has shown that Dinotefuran and Bifenthrin yield excellent results. Both options kill SLF. The choice depends on the time of year.
Giroud Program to Control Spotted Lanternfly (SLF)
With a single focus to control SLF at the most vulnerable time in its lifecycle, Giroud’s SLF Program is based on the latest research and guidance from Penn State, the PA Department of Agriculture and the USDA.
Target Trees: Since SLF feeds on so many species of trees, Giroud recommends protecting only the high-risk trees that are most valuable to your landscape
Timing and Treatments
July-Mid-September: Dinotefuran is applied as a Basal Trunk Spray. It kills SLF both on-contact and systemically. For a few weeks after treatment, SLF are killed on contact or when they crawl on treated surfaces. After the insecticide is absorbed through the tree’s vascular system, SLF are killed when they feed on the tree. Treatment remains in the tree for up to 60 days.
September-Mid-November: Bifenthrin is sprayed on trees with SLF (pictured). This treatment kills SLF on contact and when SLF walk over surfaces with the residue on it.
Number of Treatments Required: For the best protection, a systemic treatment, early in the adult stage, is recommended, followed by a systemic or contact treatment in Fall. This approach targets adult SLF when pressure is most intense and hard to control. The exact number of treatments will depend on the timing for the Adult stage each season and the point in the season when your first application is completed.
Fertilization: Fertilizing trees is also important to promote healing and build strength.
Destroy Tree of Heaven (Ailanthus)
While SLF attacks many of trees found in your yard, Tree of Heaven (Photo Credit: E. Smyers) is the favorite host tree. It’s like a magnet. Any Tree of Heaven on or near your property will attract SLF. That’s why, this tree must be destroyed.
Our Tree Care team is trained to handle the Tree of Heaven. It’s not simple. Tree of Heaven is invasive and has no natural predators. It spreads fast. The tree must be treated with an herbicide to kill it. Then, if desired, the tree and stump can be removed after 30 days.
The first step is to have your Giroud ISA Certified Arborist inspect your property for Spotted Lanternfly and determine the best steps for control.