Be on the lookout!
The mild winter has the staff of the Leffel Center at University Park, PA on high alert. The summer of 2016 saw infestations across the state of the ambrosia beetle (Xylosandrus germanus). In the research orchards at the Arboretum at Penn State over 40 infested trees were removed and burned in an attempt to decrease the population size of this potentially devastating pest. This year is likely to bring similar infestations. Ambrosia beetles favor small trees <3″ diameter as well as stressed larger trees. They are generalists and will attack hundreds of species of trees, including conifers. You should be monitoring now! Expect initial infestations when temperatures reach 70°F on 5 or more consecutive days.
Step One — Control starts with monitoring — determine if Ambrosia Beetle is present before you spray.
Deploy traps on or just before the first 60°F days. You can build your own trap with these easy instructions:
Monitor traps a minimum of twice per week or any day temperature reach 60°F.
Monitor trees for small “pin holes” or frass tubes. They can be difficult to see and the tubes are easily blown off by wind/rain. If a tree leafs out then suddenly dies back inspect the stem carefully.
Step Two — Control
Burn and remove any infested trees as quickly as practical/possible.
Spray: If traps confirm ambrosia beetles are present an application of a bifenthrin based insecticide can be effective in preventing infestation but must be applied just before temperatures reach 70 F, and reapplied based on product label recommendations. Some insecticides last up to 2 months. One hundred percent saturation of the main stem is critical for tree protection. Spray should cover the first 5-10 feet of the main stem, first scaffold branches and any exposed roots.