Fungus gnat on seedling media
 

Hi,

A week ago i purchased 10 Cattleya seedlings, "newly" deflasked, from a nursery. I separated 5 of the seedlings and attached them to a big piece of lava rock (midst 5 times a day) and they are growing faster (bigger leaves and root) than the ones remained in the original pot.

A few days later, I noticed small flies around the pot. Thinking it might be fruit flies, i took the pot (and the lava rock) into another room. I can see these same "flies" are flying/crawling everywhere around the pot. Google pictures indicated it to be fungus gnats. The seedlings are growing new roots, leaves and several have new growth at their side. I have also found tiny baby plants underneath the bark between the roots.

So, should i disturb the seedlings (im guessing several weeks old) by :
1) repoting them on fresh media?
2) dose the pot with hydrogen peroxide and rinse thoroughly with distilled water?


Thank you so much for your time.

J

Better not use hydrogen peroxide. Maybe put one of those automatic puff sprayers (pyrethrum spray) that puffs some pyrethrum into the air every hour or so ----- to ward them off.

Or use some 'mosquito dunks' solution.

Thank you. Unfortunately, due to my sensitive skin and breathing issues, i have to avoid "toxic" chemicals. The plants are now placed in my bedroom with proper lighting.

If chemicals are the only way to treat this situition, i guess i have to give them up to some other orchid lover :(:(

Most welcome Jeremy. Could double-check ----- 'mosquito dunks' are mentioned by people to be non-toxic. But certainly double-check on it ------ just in case.

You don't need to use any chemicals at all. Here is something a lot of cactus and succulent growers use for seedling pots. Set a small fan blowing across the plants. A computer CPU fan is strong enough. The gnats are very weak flyers. The fan will blow the adults away from the pot as they emerge from the pupae. They will never be able to get back to lay their eggs and your infestation will be gone.

CPU fans run on DC current. You can take any old AC to DC transformer from an appliance, like an electric shaver or radio, and connect it to a CPU fan. You can probably find corded transformers at a second-hand store. Cut the transformer cable from the connector near the device, and strip the two wires. Twist one wire to each wire coming from the CPU fan, and cover with a piece of electrician's tape, or a plastic wire nut. When you plug in the transformer the fan will operate.

Thank you estación seca. That's a neat idea. will increasing the airflow at these baby seedlings cause the media to dry out faster and the need to increase the daily misting?

Look up 'mosquito dunks' too Jeremy.

Honestly, those gnats pose no threat to the plants and are really more of a nuisance to humans. I would just let them be.

If you really want to get rid of the gnats there are sticky traps you could use that wouldn't require chemicals in the air. Alternatively, Pingicula (carnivorous plants) are very effective at attracting and removing fungus gnats from a localized area.

---------- Post added at 10:13 AM ---------- Previous post was at 10:11 AM ----------

Oh, definitely DO NOT disturb the seedlings. That would be another stressor at delicate time for the plants.

Thank you SouthPark

---------- Post added at 06:01 PM ---------- Previous post was at 05:51 PM ----------

Thank you so much ISURUS.

---------- Post added at 06:04 PM ---------- Previous post was at 06:01 PM ----------

It just crossed my mind of creating a CO2 chamber by putting the whole pot and a small mug( with a mixture of yeast,sugar and water) next to each other inside a container. Then put the container in a ziplock bag and try to remove as much air as possible before seal it tight for an hour. I am wondering if the lack of oxygen together with the increased CO2 from the mixture will kill the fungus gnat. Would it also damage the seedling being exposed to high CO2? Hmmm...

You'll just get more once those are gone, so you'll need a better long term solution.