Citrus trees Sooty Mould

[pigletwillie]

The lemon tree that I have has a good case of sooty mould. Now that the greenhouse is heated this should be prevented in future, can I just wash this off with soapy water

[Jenny Green]

I may be the bearer of bad news. I don't think the mould has been caused by damp conditions. I think it's come from scale insects. These secret a honeydew that the mould grows on.
Check the stems for limpet like creatures. Citrus are incredibly prone to these.
In answer to your other query, I think Meyer's is the recommended variety for reliable cropping in this climate. I had one of these and it withstood the climate well, but with scale insect infestations and general fussiness I binned it and now get my lemons from the supermarket!

[sally wright]

Dear Pigletwillie,
don't use soapy water as the soap will ruin the waxy cuticle on the leaves. Use a solution of vinegar and water and spray it onto the plant and wait to let the mould soften and then wipe off with a soft cotton rag (or similar). It will also get rid of any limescale deposits.
Regards Sally Wright.

[pigletwillie]

Thanks both,

yes it does have a scale insect infestaion. I will pick them off and then spray with vinegar and water and gently wipe the mould off. The mould only appeared whilst in the greenhouse, obviously I need to keep more of an eye on it.