The Plate Cleaner’s Club
Written by: By: ISA Certified Arborist, Jake Kubisiak
Ever since I was young my father instilled a strong value in our family; finish the food on your plate. Since both my parents are great cooks it was usually easy for me to accomplish. A friend of mine calls this “The Plate Cleaner’s Club”. Finish all the food on your plate and you are awarded membership. The parents of Viburnum Leaf Beetle larvae must be proud of their children’s membership in this club. The thoroughness of the little larvae’s ability to chew off seemingly every last green part of leaf from Viburnum shrubs is astounding.
In Wisconsin, this insect was first discovered in north Milwaukee County during 2014. Over the past several years Arborists at Wachtel Tree Science and our clients have witnessed the spread across most of southeastern Wisconsin. While shocking to discover a nearly leafless tree or shrub from insect damage, most plants can survive a one-time defoliation. However, since the timing of defoliation is so early in the growing season, individual Viburnum shrubs can be severely damaged from one defoliation.
Viburnum are a very common shrub in the landscape and native areas of Wisconsin. Generally speaking they are hardy and low maintenance. In the landscape Viburnum varieties offer a wide variety of amenities important to homeowners. Attractive spring season flowers turn into clusters of fruit which are a food source for various types of wildlife. Fall leaf color adds landscape interest and usually thick branching offers wildlife habitat and visual screening. One of the most common varieties, Arrowwood Viburnum, is certainly a favorite of this insect with Cranberrybush Viburnum a close second. However, it is our experience that most varieties of Viburnum can be targets of this insects feeding.
Viburnum Leaf Beetle overwinters on these plants in the egg stage. During early spring the eggs hatch and begin feeding. Since spring weather can variable, each year gives a bit of a different window for optimal treatment. The larvae are very small at about 1/3 of an inch long and usually yellow to gray with black dots and striping. Unfortunately, with up to 500 eggs laid per female they can quickly overwhelm an entire shrub, usually before most garden lovers may notice any problems.
– Both the larvae and adults feed on Viburnum leaves.
– All types of Viburnum are susceptible to damage.
– Early season treatments are most effective to control damage as this controls the larval stage.
– A possible alternative to treatments is considering replacement with alternative shrub species.
If your property contains Viburnum shrubs that you would like to retain long term, now is a good time for an evaluation by your Wachtel Tree Science Arborist. Treatments should be set up prior to the Spring season to allow proper timing of treatments by our team.