Black Twig Borer

[nn2222]

I have recently discovered that many of my orchids are infested with what must be Black Twig Borer. Can someone give me suggestions for controlling this problem. All of the pseudobulbs on some of my Dens. are affected as well and scattered pseudobulbs of Catts.

[Orchid Whisperer]

I had not heard of this before this post, but it is a pest of both trees and orchids.

Obviously I've never had this problem. Most likely you will need to do a good bit of Google searching to find a method of control. With trees, destruction of infested stems is recommended. With orchids, maybe a systemic insecticide? You might want to see if anyone has successfully used Bacillus thuringiensis.

Good luck!

[Leafmite]

I just read about them. It doesn't seem like there is too much you can do because by the time the plant shows ill effects, the damage is already done. Being inside the plant protects them from most anything you could treat them with except a systemic. You could look for the little holes and remove the infected parts (seems like they recommend freezing or burning to prevent the spread) and then keep treating with a systemic or Malathion (every two weeks) and hope that kills any of the bugs trying to bore into your orchids.

It seems that the mother bug bores the hole and carves out a chamber, then plants fungus in the plant before laying her eggs. By the time the eggs hatch, there is a fungus garden. Prevention is the only 'cure'.

[estación seca]

Welcome to the Orchid Board! Sorry you have to join with this awful problem; we look forward to hearing from you on happier topics.

I would echo the 'prevention is the cure' idea. We have a similar bug here, the Agave weevil. This is the "worm" in cheap Mezcal liquor. Mom smells an Agave about to bloom, full of starch and sugar, during the dry spring. She flies in and lands on the ground next to the stem. She burrows into the stem and lays her eggs. The larvae hatch and begin eating their way through the stem. The rainy season comes, and fungus enters the hole in the stem. The Agave collapses and rots just as the larvae metamorphose into adult weevils, who fly away to spread the love.

The weevil is native here, and our native Agave species are somewhat resistant. Some species are not attacked at all. It is not possible to grow Agave species related to A. americana in metro Phoenix without regular pesticide treatment; they only last a few years before the weevil finds them.

We do two things: When planting agaves, we mix imidacloprid granules into the disturbed soil. This is a systemic insecticide. It lasts 5-10 years. And, we drench plants monthly, from spring to fall, with a pesticide solution. For this permethrins suffice - so far.

As to your plants already infested - I would unpot them, manually extract all the larvaenyou can, and then soak the plants in a dish soap solution for 8-10 hours. Use 1 Tablespoon (15ml) per quart (approx 1 liter) of water. Shake the plant in the solution so it gets into the holes they bored. This will drown many of the larvae.

I would also put a net around affected plants, so emerging adults cannot escape and infest other plants.

[bil]

Imacloporid aka Confidor, tho there are cheaper generic versions that are just as good.

Give it a good soaking with that. If it is an ongoing problem a spay or two during the year should do it..