As I’m sure you already know, holes in plant leaves are a bit unusual and certainly not the norm for most varieties of plants in existence.
This goes the same for Rhododendron’s as holes in the leaves indicate that something out of the ordinary is going on here.
Without a shadow of doubt, pests are the number one cause for holes in the leaves of a Rhododendron, but there are a few other reasons as well.
Below you will find everything you need to know about this issue and what can be done.
Pests
Most people would probably assume pests are the reason for holes appearing on the leaves of their plant, and they would be correct as this is the case most of the time.
Rhododendrons can be affected by several different kinds of pests including but not limited to the following.
Aphids
Aphids are one of the most common pests found on plants in general and can cause some serious damage to your Rhododendron, especially when they gather in swarms.
These sap feeding pests are pretty small and can range in color from black, brown or white.
These pests can not only cause holes in the leaves of your Rhododendron, but they can also cause stunted growth, yellowing, curling and a host of other issues as well.
They can be found on either side of the leaves or branches as well.
Thrips
Thrips are very tiny pests with wings that can and will feed on the sap of your Rhododendron, causing punctured holes in the leaves.
If you notice streaks, silvery coating or small white patches then odds are you have a thrips infestation going on.
Thrips are also a type of pest that can cause Rhododendron leaves to turn black due to leaving behind honeydew, which eventually turns to sooty mold.
Overall, just like every other pest, they are annoying to have around.
Spider Mites
Spider mites are another type of pest that you can encounter when growing Rhododendron’s.
These small pests are also another type that will puncture the plants cells to get the sap for itself, causing small holes in the leaves.
Some signs you have spider mites include bronzing, yellowing, and the most telltale sign, webbing.
These bugs are usually found on the underside of the leaves so don’t neglect checking there when you suspect you have a pest issue at hand.
Slugs
Slugs in general are seen as pretty harmless, but they certainly can feed on the leaves of your plants, causing holes and bite marks on the leaves.
Most of the time they really only show up after dark, so you may have to use a flashlight to see if they are the culprit if all else fails when checking for other pests.
How To Get Rid Of These pests
There are several ways you can treat a pest infestation for Rhododendrons ranging from easy to annoying.
For some pests you can get away with just spraying some pressured water, in hopes of the pests getting pushed off the leaves.
Easy? Very easy, but effective, results may vary.
Another way you can remove most pests is by using a cotton swab, dipped in rubbing alcohol to remove them by hand, one by one.
Easy? Not so much as this can be super tedious and you would have to actually be able to see each pest up close, but this can be highly effective.
Lastly you can use insecticides or pesticides as a means to remove them and help them stay away.
My go to is neem oil as it can be used for not only pests, but fungal issues as well.
I prefer premade sprays as it’s ready to go without having to add or mix things.
Easy? Super easy and highly effective against pests.
I recommend this neem oil if you’re looking to finally try some out.
Just be sure to spray thoroughly on both sides of the leaves and keep your Rhododendron in shade until it dries out.
Overall, you want to choose the method that works best for you and get’s the job done.
For the most comprehensive guide on dealing with Rhododendron pests, you can check out the article I wrote how to get rid of bugs on Rhododendrons.
Leaf Spot
Another cause for holes in Rhododendron leaves can be attributed to Rhododendron leaf spot disease also known as Cercospora leaf spot.
This is a fungal issue that can be spready through water, wind and tools used in gardening.
If your Rhododendron has acquired this issue, you can expect to see small circular brown spots before holes appear and then cause the leaves to fall off.
How To Treat
If you suspect your plant has leaf spot, you should first isolate your Rhododendron from other plants to reduce the chance of it spreading.
Next you will want to prune away affected parts of the plant and dispose of the parts somewhere where it won’t spread again.
Now you should apply some form of fungicide such as neem oil or other fungicides to the remaining areas of the plant.
Keep in mind that if leaf spot has occurred, there is no guarantee the plant can be saved, but the sooner you act, the better chance your plant has to survive this.
Should I Prune The Leaves?
In the case of leaf spot, you should absolutely prune back or cut away the affected leaves to prevent the spread of the fungal disease.
If the holes have been caused by pests or just accidental holes from mishandling the plant, then you don’t have to prune them back.
With that said, for the sake of aesthetics, pruning back damaged leaves with allow your Rhododendron to use maximum energy towards new growth.
Pour Conclure
So there you have it, a few reasons why you have noticed holes in the leaves and what you can do about it right away.
As always I hope you find which one of these causes is the root of the issue and are able to correct it so you can have a happy and healthy Rhododendron!