Dear Orchid Doc:

I see my orchid leaves are getting a black thing that, when I touch it, kind of comes off on my fingers.

Can you tell me the best way to get rid of it?

Ali Mac

Dear Ali Mac

The black you referred to is called sooty mould. Sooty moulds fungi are caused by sucking insects. In order to get rid of it. you must get rid of both the insect and the fungus at the same time.

The best chemical for the fungus would be Champion, mixed with an insecticide, like Caprid, that is for sucking insects. However, Champion has copper as one of the active ingredients, so if the sun catches the orchid it will scorch it. If you can remove the orchid from the sun then I would suggest you get the chemicals at any farm store.

For those of you who would prefer not to use insecticides and fungicide,

Dishwashing liquid mixed with a little cooking oil and applied with a sponge works fine.

Dear Orchid Doc:

How do I know when to repot my orchids?

SS

Dear SS

Firstly, always remember if you oversize your pots when planting – and this goes for most plants. Your plants will concentrate on growing roots to full pot before it start to grow upwards. Having said that, you need to repot when any of the followings occurs:

1. The medium has turned into mush; otherwise it will cause fungus.

2. The roots have walked out of the pot.

3. Plant keep toppling over being top heavy.