Snowball bush

(Question)

We live on the waterfront in BC in a zone 8 and have a snowball bush approximately 50+ years old. It has always been very healthy until this year. About half the plant (a very large one) appears to be almost dead, the rest seems attacked by something. All the leaves are being eaten and have taken on a laced look. The plant is being watered adequately. This is beautiful plant that is stunning when in bloom. Help!!!!

(Answer)

Thank you for your inquiry regarding your snowball bush.

Without examining the plant, a definitive answer is difficult, but from your description, I suspect an infestation of the viburnum leaf beetle Pyrrhalta viburni (Paykull).  Both the adult and larvae feed on the fleshy portion of the leaf between the midrib and larger veins. This gives the leaves a lace-like or skeleton appearance. Defoliation for 2 or three years may kill the tree. Closely examine small twigs for egg laying holes and scars to aid in diagnosing the problem.

The following websites provide a wealth of information about the VLB:

https://oregonstate.edu/dept/nurspest/viburnum_leaf_beetle.htm

https://www.hort.cornell.edu/vlb/manfaq.html

Control

The following websites contain information about both cultural control and the use of pesticides. Provincial regulations regarding pesticide use take precedence.

https://cru.cahe.wsu.edu/CEPublications/FS202E/FS202E.pdf

https://www.hort.cornell.edu/vlb/manage.html

Viburnums are beautiful throughout the year. Hopefully this information will help restore health to your bush.