Rhododendron Leaf Problems And Diseases
There are many reasons why your rhododendron leaves turn brown. You may have one or several of them.
They could be due to various diseases, insects, weather conditions, soil conditions, pests, fungi and other factors.
So what do you need to do? What should you look out for? What are some things that will cause your plants to die?
These are all questions that you may ask yourself.
What Causes Your Leaves To Turn Brown?
Insects: Rhododendron leaf problems and diseases can be caused by many different types of insects. Some of these include aphids, scale insects, whiteflies, psyllid flies (also known as leafhoppers), mealybugs, thrips and others. Aphids are small insects that feed on the leaves of most flowering plants. They’re usually found under the bark of trees, but they can also be found inside the trunks. They’re very tiny and difficult to see with the naked eye. When they bite into a plant’s leaves, it causes damage which results in yellowing and wilting of the leaves.
Aphids are usually green, but they can also be black, brown, red or even pink. They move very slowly, but this doesn’t mean that you won’t notice them on your rhododendrons.
You’ll notice a little streak of yellow on your plant’s leaves when they’re finished feeding on them. They also excrete a sweet liquid called honeydew, which is often lapped up by ants. This is a big problem, because the ants end up protecting the aphids in exchange for the honeydew.
There are many species of aphids, and most species reproduce very rapidly. The mealybugs are also small insects that cause damage by feeding on the leaves of your rhododendron.
They’re white in colour and tend to make a mealy paste under the leaves. They also excrete a lot of honeydew, which can create a lot of problems.
Other insects that can cause damage include psyllids, whiteflies, leafhoppers and thrips. You may also have problems with caterpillars.
These are typically the harlequin butterfly, which can completely defoliate your plant if not kept in check. If you notice any of these insects on your rhododendron, you need to take immediate action to eliminate them. There are many different methods you can use to kill the insects infesting your rhododendron.
Insecticides: You can use an insecticide to kill aphids, mealybugs, psyllids and other soft-bodied insects that you can find on your flowers. There are several different types of insecticides you can use to get rid of these pests.
Many gardeners prefer organic insecticides. These insecticides break down over time and are less harmful to the environment.
If you’re using an organic insecticide, you also need to decide whether you want to use a contact killer, systemics or a micro-encapsulated formula. A contact killer destroys the insect’s ability to grow and reproduce, but doesn’t travel through the plant’s vascular system.
Systemic insecticides are absorbed through the leaves and transported through the plant’s vascular system to every part of it. Systemics can be harvested and the plant will not die. A micro-encapsulated insecticide changes the pH balance of the insect and kills it instantly.
If you’d rather use a chemical insecticide, there are several different ones to choose from. You can use an organophosphate to kill the aphids and other insects that you find on your rhododendron.
You should only apply it to the part of the plant that’s infested and can cause damage if it gets into the soil. If you have a systemic insecticide, you can mix it with oil and pour it over the soil to get rid of the pests that way.
You can also use a carbamate, which is effective at killing most insects. It’s popular among gardeners because it doesn’t harm animals or humans as long as it isn’t ingested.
You can also use a pyrethrin to kill the insects on your rhododendron. These work quickly, which is why they’re so effective.
Insect Controls: If you don’t want to use insecticides, there are several other ways you can go about controlling the insects on your plant. One of the most popular is to introduce natural predators to your garden.
This will eliminate most of the aphids, caterpillars and other pests that are feasting on your plant.
You can also pick off the insects yourself. This is obviously a time-consuming process, so you’ll have to decide whether it’s worth it or not.
You can also try using barriers to protect your rhododendron from the insects. You can plant marigolds around your rhododendron to help keep the insects away.
If you have the time and want to protect your rhododendron without using chemicals, this is a good option. You should also investigate beneficial insects, such as ladybugs and lacewings, which will eat the bad insects in your garden and help eliminate them naturally.
Whichever way you go about it, your rhododendron is sure to flourish if you take the time to care for it. By using any of these methods or a combination of all of them, you should be able to eliminate the insects that are currently infesting your beautiful plant and keep them from coming back in the future.
Sources & references used in this article:
The cultivation of rhododendrons. by PA Cox – 1993 – cabdirect.org
The red list of Rhododendrons. by D Gibbs, D Chamberlain, G Argent – 2011 – cabdirect.org
Rhododendrons of the World. by DG Leach – Rhododendrons of the World., 1962 – cabdirect.org
Some relevant problems of Rhododendron introduction in Lithuania. by A Malciūtė, JR Naujalis – Botanica Lithuanica, 2010 – cabdirect.org