You may have noticed the fairly sudden decline of ornamental cherry trees in our area over the last few years. This is due, in large part, to a quiet unseen moth and its larvae, the Cherry Bark Tortrix (aka CBT).
These moths begin laying their eggs in the cracks and crevices in the bark of susceptible trees in April through September. The Larvae mine around in there, doing considerable damage all the way to the cambium layer, causing a disruption to water and nutrient flow to the canopy of the tree. This can result in the complete dieback of entire branches and eventually the whole tree will succumb.
If you have observed this dieback on any cherry, hawthorne, crabapple, plum or any plant in the rosaceous family, take a look at the bark for telltale “frass” tubes. The larvae clear out their “mines” and push the debris out a small hole in the bark, forming a small tube (More like a small nubbin made of sawdust). This is the only observable sign that CBT is at work in a tree, other than the resultant branch dieback.
Research has discovered that there is a weak link in the overlapping life cycles of this destructive insect and that a well timed insecticide application in late September/ early October to the frass tubes will control CBT since the larvae make contact with these tubes repeatedly.
You can do your part in reducing the damage that Cherry Bark Tortrix is doing in our area by inspecting your trees for these telltale signs or we would be happy to have a look for you and make recommendations accordingly.
Thanks for reading!
Evan Ogden Senior Technician