Sooty bay tree

[Ranter]

My potted bay tree has developed a soot-like marking on the leaves.

Anyone know what this is? & will it help to wash the leaves with pure soft soap?

[Millymollymandy]

It is sooty mould. What happens is that you get aphids (or more likely on a bay tree it is scale insect) which secrete honeydew, that sticky stuff, which in turn turns into sooty mould.

Yes you can wash the leaves off. I once had to do that with my bay tree and I think I just used soapy water. It took forever because my plant was so big.

It's worth looking at the undersides of the leaves and on the stems to see if you have scale insect.

[Ranter]

Aaahh, thanks MMM,
The tree does have scale, I already knew that, but didn't know about the mould.

I've done enough for today now, but tomorrow I will wash the leaves.

Cheers

[Millymollymandy]

No probs! Hope the plant isn't too big. Try to squash the scale insects whilst you are cleaning it too.

[Ranter]

The plant isn't very big, it's in a pot & I'm training it into a standard. I washed all the leaves in pure soft soapy water & it seems to be doing fine. I got rid of every scale insect I could see at the same time.

I didn't realise that scale insect could cause this kind of problem & will act quicker next time I get an infestation.

There's quite a lot of new growth on the tree & luckily that was unaffected by both scale & mould.