I recently noticed my Bay Leaf tree had ‘black stuff’ on the tops of the leaves, and the leaves themselves were being eaten by something. Given that it had cost me at least a good £15 to buy and that I do use the leaves in cooking, I figured something needed to be done quick.
It turns out that the problem is called ‘sooty mould’. During the warmer months, I had placed the tree in a position more exposed to the weather. Worried that it wouldn’t cope in the colder seasons, I had put it in my porch. This seems to have caused the problem of sooty mould to take hold. Normally, rain and sunshine stops this from happening.
Some sort of sap-sucking pest is enjoying the Bay Leaf and excreting honeydew. As the honeydew is not able to be washed away in the rain, the mould has developed and taken hold.
Thankfully the solution is quite simple: lukewarm water and appropriate insecticide. The sooner you do it the better. I was surprised at how firm I had to wipe the mould off with the sponge!
As soon as the danger of frosty weather is gone, the plant will be moved back out again.