After a cool spring I was beginning to think the ambrosia beetles would never come out. Although we have found a few early non-pest species we have not seen the main -granulate ambrosia beetle- until now. We found a couple in traps at cooperating nurseries in Johnston Co, NC. Of course it is freezing this week which could delay them again. The same thing happened last year when we got a few at a time as the weather alternated
between warm and cold.
In experimental trees at lake wheeler and sentinel trees at nurseries we have not had any attacks but it is probably time to start management if you haven’t already.
Management of ambrosia beetle damage requires pyrethroid applications every 3 weeks to the trunks of trees. Ambrosia beetles usually attack below the first scaffold branches so you do not need to spray the canopy. Most folks apply permethrin with an airblast sprayer. We have tested a manual sprayer and fold more complete, even coverage.
You can read about it in a recent paper. The manual sprayer has two opposing nozzles to
quickly cover tree trunk with insecticide. It takes a little longer but uses less insecticide and reduces drift and secondary mite outbreaks. Ambrosia beetle attacks also increase when trees are overwatered so resist irrigation until it is warm and trees start leafing out. Summaries of ambrosia beetle biology and management can be found in industry articles, an open source publication in the Journal of IPM, and in a free iBook about nursery pest management