Unwanted mushrooms in a yard or garden can be very difficult to kill because the visible cap of the mushroom is only the fruit, and each fruit has thousands of tiny spore seeds. Even when mushrooms are removed, their underground mycelia sources can remain, according to a study by the University of California Statewide Integrated Pest Management Program. You must get to the root of the source to be able to kill the mushroom spores, and there are natural and chemical methods available.
Natural Method No. 1
Find the underlying cause of the mushroom growth, including areas of rotting wood or rotting leaves. Remove any dead tree roots or branches that are creating a supportive growing environment for the fungi.
Change the soil's environment. Use your shovel to dig up the dirt around the mushrooms to locate their roots. Dig a foot deep, and then add gravel about 3 inches deep. This will hinder the growth of new roots.
Clean your shovel with bleach and water to prevent spreading any spores that may be on it.
Natural Method No. 2
Add 2 tbsp. of baking soda to 1 gallon of water in a bucket.
Stir the mixture and allow it to dissolve.
Transfer the mixture to a spray bottle, and douse mushrooms, caps and stems. Spray the earth around the mushrooms as well.
Read the label on your purchased fungicide. Pay attention to the mixing ratio, spraying directions, safety equipment required and warnings.
Wear and long-sleeved shirt and pants, protective gloves, closed-toe protective shoes and safety glasses.
Mix the powered fungicide with water at the specified ratio in a wind-protected area, and then transfer the mixture to a spray bottle.
Spray the mushroom caps and stems as well as the earth around them.
Follow the directions on the label on how to dispose of any leftover fungicide. Clean the spray bottle and mixing bucket with bleach and water. Wash any clothes that may have come in contact with the spray.