After a bad outbrake of fungus gnats I have learned many things about them, to help you identafy these pest and the symptoms that accompany them, I want to list what I noticed, and please anyone with insight on these pest, please enlighten the rest of us, I want to create culmination of benificial information on these pest and how we can most efectivly fight them.
1. visually seeing small blackish gnats flying and landing on your plants, or crawling on the soil.
2. you notice leaves dieing and leaf damage that appears like something is eating away at the leaves but actually the leaves are dieing due to the roots supplying these leaves are being eatin by the varva soil dwelling babys of the fungus gnats .
3. your leaves appear dry, not wilted but dry, crumbly feeling, some may yellow on you with brown spots noticable before they fall off compleatly.
4. 1 fungus gnat has the ability to reproduce and destroy your whole garden, even if your plants are 5 feet tall, and they do it from the soil, the gnat itself doesn't really cause the damage, but they lay eggs in your soil and with a little moisture they hatch becoming larva that eat on fungus and the tender roots of your plants, roots die below, plant dies above.
I have here 1 very good idea suggested by sickboy to compleatly illiminate these past, after reading, again if you have something to add, methods, insectasides, whatever might help people reading this control these pest.
also need to cover your pots so no adult fungus nats can get in or out of the soil. if they cant get out or back in they cant lay eggs and reproduce. i have found that this is the only way to kill them 100% heres the steps i take.i drench the soil with azamax and then right after i cover each pot with panda plastic,white side up and i make sure that theres no way for adult gnats to enter drain holes. i use tape around the stalks so there is no little holes for any to escape. then i will spraythe leaves w azamax. when i need to water i will take each plant out one by one, out of my grow room, and water individually, so if any adults come flying out they are not stuck in my room, i do it outdoors, then i will put the panda back on making sure no little holes. my water and nutes have had an airstone in it for at least 12 hours so roots get good oxygenated water. i left panda plastic on for three weeks. the life cycle is said to be about two weeks from hatch to death,thats why i do 3.to make sure that all eggs have hatched and gnats have died. my experience just doing the drench and sprays just controls them and doesnt fully eliminate. you will end up thinking they are gone and a month later you will get a bad break out again. hope this is helpful, letme know your outcome