Around the beginning of August each year, invasive European or "common" buckthorn (rhamnus cathartica) berries begin to ripen. As seen in these photos, the females produce dense clusters of fruit, which change from green to purplish black. Once the drupes are ripe, they are viable and ready to spread. Buckthorn colonizes by dropping its seeds straight down to form a thicket, and creates new infestations using birds. Unfortunately for the birds, there is no nutritional value in the berries, and it causes diarrhea, further ensuring its viability after digestion.
Once ripe, some berries can remain on the twig until the following spring, making it available to birds for more than half the year.
This is a good time to remove female buckthorn, because they are easy to identify, the unripe berries hang on better than ripe ones, and unripe berries do not cause purple staining on hard surfaces and equipment like the ripe ones.
If you would like help identifying, removing, or replacing buckthorn, or if you could use some guidance for your DIY project, please call 612-564-5771, email email@example.com, or submit a request on our website.