Dear Orchid Doc:

Help! My orchids are sick. The dendrobium leaves are dark brown and it doesn’t rub off. What can I do?

— JP

Dear JP

You seem to have what is known as orchid rust.

Mix 2 teaspoons of Topsin with a teaspon of Caprid in a gallon of water, spray once per week, preferably when it is cool, (as the sun will cause the chemical to burn) for 3-4 weeks, then once every two weeks for a couple of months, then back to your regular routine. When using the Topsin as a preventative, use one teaspoon instead.

Your plants should be better within four weeks; however, the old rust will not come off the leaves unless you pick the leaves off.

Dear Orchid Doc:

I have been bitten by the orchid bug, but I am frustrated by Dendrobiums because they grow so slowly and I am discouraged by this. Any suggestions?

— Bridget

Dear Bridget:

It seems like you might need to add humidity. There’s a greenhouse plastic that will be able to help. As a matter of fact, you should see improvement within a month. It is a clear plastic specially made for greenhouses which can be found at most garden stores.