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It is late spring and my bay tree has started to grow new leaves. The majority of these look perfectly healthy but I have noticed abnormal growth on the edges of several leaves where they have started to curl up on one side and turn yellow.
On the affected leaves, the curled up areas are also significantly thicker than the rest of the leaf. I had not come across this before so was anxious to find the root cause, and stop it.
Curled up bay tree leaves can indicate the presence of the bay sucker insect (Lauritrioza alacris). Bay suckers feed on the sap of the leaves which causes the edge to curl. The bay sucker will then lay eggs inside the curled leaf section and, once the eggs hatch, the subsequent larvae will also feed on the leaf. This process causes the curled leaf edges to thicken and turn yellow and eventually brown.
Bay suckers hibernate over the winter period so you are most likely to notice this type of damage to your bay tree leaves between May and October in the UK, as this is when bay suckers are at their most active.
What are bay suckers?
Bay suckers are sap sucking insects. They have 2 wings, are brown in colour and are around 2mm long. The only thing they feed on are bay tree leaves – nothing else.
I uncurled one of the affected leaves. This is what I found.
Below is one of the thickened, curled up leaves that I have removed from my bay tree. The curled up section is starting to discolour:
I uncurled the leaf and you can see a wet, white waxy type deposit within the curled up section. The bay suckers have laid their eggs within the curled section of this leaf:
When the eggs hatch, they produce larvae which will eventually develop into fully grown bay suckers.
The larvae feed on the leaf which progressively causes even more damage.
The leaf damage pictured below is at a much more advanced stage, the leaf has started to uncurl and turn brown. As they develop, the larvae will secrete a fluffy, white substance – you can see plenty of larvae on the underside of this leaf.
From the eggs initially being laid to this stage of damage typically takes around 2 – 3 weeks.
Will bay suckers kill my bay tree?
The good news is that bay sucker damage does not usually pose a significant long term threat to the wellbeing of your bay tree. The damage to the leaves themselves is primarily cosmetic and will not usually affect the future growth of the bay tree.
The suckers do excrete honeydew so you may also notice that there is a sticky substance covering some of your bay tree leaves, this in turn can lead to the growth of sooty mould on these affected leaves.
How should bay trees affected by bay sucker be treated?
There are four main options that I considered once I had identified the presence of bay tree sucker on my bay tree.
1 – Pesticide treatment
The first option I considered was to use a pesticide treatment to rid my tree of the bay suckers. But I generally try to avoid the use of pesticides wherever I can in the garden, especially as I want to use some of the bay leaves for cooking. That said, there are certain sprays available that are designed for use on edible crops. But I am going to be concentrating on more natural methods to try and resolve my bay sucker problem.
2 – Remove affected leaves by hand
The next option, which I decided to take, is to remove all off the affected leaves by hand to try and limit the bay sucker population that way. The sooner the affected leaves are removed the better. Luckily I noticed the problem quite early on in the year and there were only around 20 affected leaves on my whole tree. The leaves that I removed are shown below – interestingly each leaf was only affected on one side, and all leaves affected were new growth.
I safely disposed of the affected leaves far away from the tree. This was to prevent any further damage to my tree being caused by bay suckers emerging from the removed leaves. Going forward, I will continue to keep a close eye on the tree for any further instances of curling leaves and will continue to remove any that I see.
It is also a good idea to clear away any dead bay tree leaves from around the base of the tree, if there are any, as bay suckers can use these for hibernation over the winter.
3 – Encourage natural predators of the bay sucker
In conjunction with leaf removal, I am also taking steps to try and encourage natural predators of the bay sucker to the vicinity of my tree. The presence of predators such as birds and ladybirds can help keep bay sucker numbers down.
You can attract ladybirds to your garden by introducing pollen rich plants such as Fennel and Dill. Providing extra shelter for ladybirds from predators, and space for hibernation, will be a further boost – check out this ladybird bug hotel on Amazon.
4 – Do nothing
It is a personal choice but a fourth option is just to do nothing, as the long term health of your tree is unlikely to be unaffected.
That said, if you have a severe infestation of bay sucker with a high number of infected leaves it can make your bay tree look somewhat unsightly so you may not want to take this approach!
And there is always the risk that, even if the problem is currently a small one, it can escalate into something much bigger if it is not addressed at the early stages……
If you have identified your bay tree problem as being down to bay suckers, you should now be armed with more information to help you decide on the best course of action!
Be sure to check out our other bay tree related posts below!
If you are looking for more (or new) bay trees, why not check out some bay trees available on Amazon below!