Yellow azaleas

(Question)

Good morning. I live in North Toronto in climate zone 6a. I bought a yellow azalea two years ago from Sheridan nurseries. Last spring all the leaves were eaten, so it didn’t bloom. This spring the same thing happened, including the blooms! I didn’t see any bugs and now a second crop of leaves has appeared that have not been eaten. What is eating them and how do I prevent this? (Their soil is mostly grow-max). Thanks very much :)

(Answer)

Considering that you live in North Toronto, it’s unlikely that it’s deer eating the leaves of your azalea. But it could be rabbits. There are apparently lots of rabbits that have been abandoned in the ravine by disillusioned pet owners. Rabbits don’t just eat leaves but they will cut through branches at a 45-degree angle. The best prevention is a galvanized steel fence around your plant. For more information on how to identify rabbit damage and prevent it, see https://articles.extension.org/pages/34725/how-does-one-identify-rabbit-damage-and-what-do-they-eat

There are a couple of other pests that are potential culprits. The Azalea Society of America says that leaf damage in late spring can be from the Rhododendron Looper, “a caterpillar that looks exactly like a branch, stem, or even a stamen. It can align itself along the stem to hide.” The caterpillars won’t kill the plant unless there’s a huge population of them. The best way to get rid of them is to pick them off and squish them.

If the leaf damage looks like notching around the outside of the leaf, it could be weevils. Again it is possible to pick them off, but it has to be done at night. You said your azalea leaves were eaten entirely, so this is probably not  the problem. But just in case, the American Rhododendron Society says: “Weevils can be picked from the leaves and plant at night if one has the patience and is willing to spend time well after dark with a flashlight. Close examination will reveal the weevils, and they can be picked or scraped into a container for disposal.”

The first line of defence for Rhododendron Looper or weevils is prevention: keeping your plant healthy and free of stress. That means regular watering, a mulch to retain moisture, regular feeding with compost, and pruning of the lower leaves that touch the soil or other plants so that pests will have less access to it.

For more information on rabbits in the garden, see:

https://www.torontomastergardeners.ca/index.php/askagardener/rabbits-in-the-garden/