Fungus and fungus gnats are two problems that can occur on any plant in a very moist and wet environment. Fungus gnats eat the fungus in or on the plant, and fungus will grow because of the bacteria in the soil along with moisture. So because fungus is the food source of these gnats, the gnats will lay their eggs on the plant as well. Indoor plants suffering from fungus and fungus gnats need to be treated a bit differently than a problem outdoors. You will know you have fungus on your plants when the fungus gnats show up. Fungus gnats are small, long-winged, long-legged creatures.
Till the soil with the spade and apply a fungicide to the soil to combat the fungus.
Allow the soil to dry out a bit, then water.
Apply an insecticide to the plant.
Repeat as directed by the insecticide and fungicide sprays.
Cut down on moisture in the room if it is a very humid environment. Remove all containers of stagnant liquid as well.
Till the soil with the shovel in areas where you have noticed a lot of gnat activity.
Spray the ground with a fungicide that will not harm surrounding vegetation.
Spray all of the plants with an organic insecticide so your plants are not harmed.
Repeat the insecticide as directed on the label.