I have read several reports about the effectiveness of Neem oil as a drench against fungas gnats. I am concerned about putting an oil based product in the soil in case it coats the roots and causes problems resulting from that. If the Neem oil is emulsified in a soap solution does that make it safe to use? I am also wondering if using it as a soil drench would make the plants less susceptible to infection with Aphids and mealy bug. Any thoughts on this.
Neem oil is not registered for use as a pesticide in Canada. If you are having problems with fungus gnats, let the soil dry out more between waterings. Or, wash off all the old soil and replant in a better draining medium & water less often.
Hello to quote Jimmyq "Neem oil is not registered for use as a pesticide in Canada." it is also not a systemic. it is atopical systemic means it acts like benomyl, cygon or latox from within the system of the plant or animal there is a product from wilsons called fugus gnat killer it is a permethryn product (Synthetic pyrethrin) that will work if the good advice jimmyq has give you does not work
A natural product called Pyroclay works incredibly well at repelling fungus gnats and it also feeds any mycorrhizal fungi in the soil. It is a powder and when applied as a light dusting on the soil surface fungus gnats leave. I use a restaurant style parmesan cheese shaker as a applicator. Letting your plants soil dry out will also help alleviate your problem. Registered or not Neem Oil is the most effective long term natural mealy and mite killer. I would not however drench your soil in it. Light soil surface sprays have never caused noticeable damage on any of my plants. Canadian legislature needs to wake up and promote more eco friendly alternatives and start banning more dangerous chemical pesticides and herbicides that destroy eco systems like round up.
I have experience with Pyroclay and have never heard claim that it can 'feed mycorrhical fungi" nor am I aware of any product that can. Mycorrhizal fungi interact with root hairs in a symbiotic relationship to garner their nutrition and such. I would be very interested to see the info regarding this. In regards to a product being registered or not, the plain fact is that if it isnt registered, you arent supposed to use or advise to use it for that purpose. If you dont like the rules thats all good and well, fight to change them :) Pyroclay is also not registered as a pesticide in Canada. I am also betting the manufacturer would not like to get any calls from PMRA asking about such claims and would be smart enough to not promote their product in such a fashion. FWIW I sold pyroclay and other Nutrilife products wholesale (along with a number of other brands) for about 6 years in the lower mainland to many stores (garden centers, hydroponic stores, health food stores) and other clients. Not trying to start flamewars or anything here, just trying to let the general public know what the rules are and what we can do with the products within them. I agree that the rules need revising.
I'd like to point out that the Dean of the Faculty of Land and Food Systems here at UBC (in which the garden is a department) has done a lot of research on Neem oil - if you ever get a chance to go to one of his presentation on natural insecticides, I suggest going.
I live in rural B.C. and wouldn't be able to attend Dr. Isman's talks even though I would like to. Is there anywhere on the internet I could read some of his papers?
Hmm... Well, here's a popular account: Bugging Bugs the Natural Way As for scientific papers, here's the listing from Google Scholar: Murray Isman - unfortunately, I can't tell while on-campus which are available to the public for free and which not (because I'm on the university network and most are freely available that way)
