My Dieffenbachia's became infected with fungus gnats, but I think that they may be on the road to recovery. I had left a bowl of water with dish soap and caught most of the gnats and I withheld watering as long as possible and just sprayed the leaves with water and Bug Be Gone. I haven't seen any flying around the plants recently. They all lost many leaves, but there is new growth and I think the gnats may be gone. I was considering replanting the lot in new soil, just in case.

The gnats got to my kitchen plants too, a young lipstick plant and a new Wandering Jew plant I was starting. They are still infected and I don't think they can be saved, as they were too young to survive. I think I may have to toss them and the soil.

My bathroom ficus was also infected and I have lost many leaves and branches. I've cut it back to the one surviving branch, but the gnats are still in this plant. My problem with this one is that I went a little crazy with spraying the gnats on sight with my water/bug be gone mixture and in doing so, the soil became wet and breeding grounds for further eggs. Duh. Anyway, I'm thinking of replanting in new soil.

Lastly, I have many other plants that are healthy, but I have treated all of my plants with Bug Be Gone when they were last watered. It is important to note that I waited a really long time to water any of my plants when I first discovered the gnats. I was so afraid of the gnats spreading. Anyway, all the houseplants were very dry and I had to break down and water them, shortly afterwards the top soil is looking like it is covered in a white fungus. The plants all seem fine and I'm going to scrape off the top soil, but if anyone knows what may have caused this, I'd like to know.

Living in Canada, I don't have access to many pesticides.

Questions:

What do you think about repotting infected plants, good idea or bad?

Any suggestions?

Should I cut back everything?

Any ideas for prevention?