Cymbidium pest help - Orchid Board

greenguru · #1 08-10-2011, 12:23 PM

I posted in the Pest and Disease forum, but have yet to get a reply. I need to erradicate these critters before they have a chance to ruin my entire Cymbidium collection. I'm hoping some of you experienced Cymbidium growers can identify and give me some advice on how to get rid of them and also preventative steps to keep my other plants safe. The post is in the Pest and Disease Forum and the thread is titled "Insect Larva Identification".

orchids3 · #2 08-10-2011, 04:57 PM

Have never observed tiny white worms in a backbulb,
wish you had taken a picture. Could it be a some kind of fly maggot or fungus gnat larvae? Are they isolated to rotten backbulbs or do they seem to be getting into fresh growth? Are they in old broken down potting media also? Sorry I have more questions than answers.

WhiteRabbit · #3 08-10-2011, 06:50 PM

Quote:

Originally Posted by orchids3

Have never observed tiny white worms in a backbulb,
wish you had taken a picture. Could it be a some kind of fly maggot or fungus gnat larvae? Are they isolated to rotten backbulbs or do they seem to be getting into fresh growth? Are they in old broken down potting media also? Sorry I have more questions than answers.

pix posted in this thread http://www.orchidboard.com/community...ification.html

greenguru · #4 08-10-2011, 11:47 PM

Thanks Orchids3 for the link! Wasn't sure how to do that. To be honest, I'm not sure if the rot started first followed by the larva or if the larva hatched, bored it's way in and started eating away causing the bulb to rot. I do know that the old bulb was completely rotted on the inside while the new growth's leaves were still green and healthy looking until I tugged on them and they popped right off and you see in the pic what the bottom of the new growth looked like. When the leaves popped off there were several of those white worms present inside the rot. Since the first discovery, I've found two other bulbs affected. One didn't have any new growth present, the other did but the rot hadn't made it's way into the new growth so I quickly removed it and have repotted it. Hopefully I can keep it alive. If these are fungus gnat larva, what can I do to keep them from spreading to the rest of my collection? Is there a systemic pesticide I can use that will kill larva that has already bored its way into a bulb? Will submerging the plant potting soil and all in a bucket of pesticide laced water work?

orchids3 · #5 08-13-2011, 11:33 AM

No sure answer here but it may be that the plant has bacterial rot and the maggots are growing in the rot. Rot may be in the bulbs before you can even see it . I would cut off all affected areas treat the wound with pruning paste. ( the kind you use when you prune woody plants) and repot in a clean mix. Wash the plant and clean off all old roots and media then dip the plant in Hydrogen peroxidebefore you pot.You may get a better identification and need to do something else but cleaning up the rotten parts and repotting would be a good start. Rotten and broken down potting mixes also
harbor this type of pest. Fungus gnats - white flies etc..
Have you seen small insects flying around in you growing area?

rodrigo · #6 08-13-2011, 06:36 PM

Quote:

Originally Posted by orchids3

dip the plant in Hydrogen peroxide before you pot.

Hi Orchid3,
Can you explain what this does?
Thanks,
Rodrigo

orchids3 · #7 08-13-2011, 08:37 PM

Hydrogen peroxide is a disinfectant. If I found a plant I thought had bacterial rot I would probably throw it away - unless it were very special then at least I would do my best to remove rotten parts and disinfect what I keep. If there is a better disinfectant maybe someone would suggest one. Some people heat an Iron very hot and press it against the cut area instead of using a pruning paste on the wound. One of our speakers at the orchid society described some new rots that are now know - that are very infectous and can spread.(USDA person.) Good sanitation in the growing area, keeping up with repotting, all help. Isolate suspect plants ----
It is better to treat bacteria with a disinfectant and fungus with a fungucide (sp).

rodrigo · #8 08-13-2011, 08:44 PM

Quote:

Originally Posted by orchids3

Hydrogen peroxide is a disinfectant.

Good point.... I would have never thought of it, but you're right!
Thanks for the tip!
Rodrigo

Bobfharris · #9 08-14-2011, 04:37 AM

There is a concentrated form of Hydrogen peroxide for plants called Zerotol. Works great. But for a general fungicide, bacteriacide and antiviral Physan is the best there is. Great to use on table tops etc and in dilute form on plants.