I'm looking to purchase Bacillus thuringiensis israelensis (BTI) or Gnatrol for the best price.

Please tell me where do you buy yours?

I have purchased it at gardensalive.com as a product labeled "Knock Out Gnats" using a coupon for a lower price. You can also buy it on Amazon. It doesn't have a long shelf life so only order what you can use within a year.

So glad Judy answered your post because I desperately wanted to post;
"At the Bacillus thuringiensis israelensis store."

I'm a worthless jackanapes but Ms. Davisson is an angel.

Charley

@DaviJK - Thanks Judy, it's actually a difficult product to locate. I could only find it on Amazon and Ebay. The lower shelf life is also really helpful information.

@Charlemagne - Ms. Davisson is truly a selfless angel, you're right. You don't fit in that jackanapes category Charley. Next time don't wait to post, I enjoy your humor.

There's a Shakespearean epithet! A Worthless Jackanapes! Lol!

Is this for indoor or greenhouse use? I definitely recommend Gnatrol. I've used it for years to control fungus gnats as they invariably appear each winter in my lily (and eventually day lily!) seedling flats I grow under lights in the basement. Use 1-3 teaspoons per gallon, drench three times, a week between drenches, and the fungus gnat life cycle should be broken. The company that makes Gnatrol only sells it in a 16 pound buck, rather pricey! I've been ordering it on eBay from a company in Florida that repackages it into smaller containers. A four-ounce container tends to be more than enough to get me through a winter treating all the flats I can squeeze onto two 2-feet x 8-feet light shelves. I have stored the remaining granular Gnatrol it in the basement over summer, and it seems to still work just fine the following year. But I do try to just buy one season's worth each time if I can. Never store in the aqueous solution, as I'm not sure how long it will remain effective.

Hi Jim, I have been using about 1/2 tsp of Captan fungicide for a gallon of potting soil for my indoor seedlings and haven't had an issue with indoor fungus gnats. I overwintered a bunch of potted-up Daylilies outdoors in the shade against my house. Fungus gnats loved the environment and I lost a bunch of them.

Live and learn I guess.

I've been trying to rescue what I thought I could and needed a soil drench to protect all of my outdoor potted seedlings (last years and this years). I found the amazon and ebay sellers to be awfully expensive for 1oz.

I had to Google "jackanapes"

Hi Robin

I can sympathize, fungus gnats have made a mess of my houseplants and lily seedlings multiple times. Plus the adults are attracted to the light of pc monitors and bathroom mirrors. My family does not appreciate that one bit, strangely enough.

I've also used Neem oil indoors as a soil drench to control fungus gnat larvae. Not sure how the cost would compare between Gnatrol and Neem per the three treatments needed to break their life cycle. In my greenhouse, imidacloprid products are very effective as a soil drench, but this is getting into a more serious insecticide that you need to wear the appropriate protective gear to use. It would work outside as well, but use only as a soil drench on non-edibles and plants not being visited by pollinators, as these products will also knock out friendly insects. Never use as an aerosol indiscriminately outdoors.

Running pots as dry as possible will lessen fungus gnat larvae. You can also put about 1/2" of sand on top of the soil of your pots. Fungus gnats won't lay their eggs through the sand.

Buy enough gnatrol to treat all your plants three times, then try sand on the soil to deter future outbreaks?

Good luck!

Jim

Thanks Jim, I sure like the sand idea! I also didn't know you could use Neem as a soil drench, I use it for foliage though.