Dear Orchid Doc:

How are you? First, I must say continue to do the wonderful job you’re doing.

My problem is that some sort of insect keeps eating the new root tip of my orchids.

When it first happened I repotted the orchids, thinking it was maybe snails or slugs in the medium. I am now certain that it’s not slugs or snails because I have not seen any slime marks. I did find a few small roaches, which I killed. I am at a loss!

Last night I was in my greenhouse until about 11 o’ clock repotting some of my Dendrobiums.

Upon waking this morning and examining my plants, to my horror the three new tips on my Dendrobiums were all gone!

I use Phyton 27 once per month, Engeo insecticide once per month and I fertilise twice per month. And then one clear watering at the end of each month. I also use only rainwater on my orchids. Could you please help me by suggesting something I could use to stop my plants being dinner for this horrible insect? I have tried going into the greenhouse and checking to see if I can catch whatever it is, sometimes even at two in the morning, but no luck. I know that losing the new roots will kill the plants that have just been repotted.

My other problem is that, even though I use Phyton 27 once per month, one of my Dendrobiums seems to have a fungus or bacterial infection; it keeps losing the newest leaves on the newest canes. The leaves turn brownish yellow with black spots, then fall off. Apologies for my long e-mail, but I really love my orchids and I am so depressed because of these two problems. I really do hope you can help. Thanks again, and please continue to be a source of strength to us simple orchid fans. Oh, I live in Westmoreland where we are now in the rainy season. Thanks again.

— Angel

Dear Angel:

I know you are insisting that it could not be slugs or snails, but from experience, it could be any of these: slug, snail, caterpillar or lizard.

With the lizard, I find that they love the blooms more; the caterpillar, I am not sure they would be out in the rainy season. The slug leaves a lot more trails than the snail. That said, I am suggesting you set some slug pellets around the base where they would be crawling up to the roots.

Regarding the fungicide – once per month, especially in the rainy season, is not enough. You have to remember that too much water will cause fungus. During the rainy season I would suggest you use fungicide at least once per week.

The loss of the leaves on the newest canes also suggests too much water.

Best of luck!