Fall seems to be mushroom season on the Central Coast. Adequate soil moisture, warm soils, and slightly cooler air temperatures appear to set off mushroom growth. Mushrooms are the reproductive structures of certain fungi that live in the soil of your lawn. There are a number of species that may be found in lawns on the Central Coast. The species of mushroom(s) present may depend on the species of trees and shrubs you have growing in your yard. Some mushrooms form an intimate relationship with the roots of trees and other plants. This relationship is called mycorrhizal (mike-core-rise-al) association. This relationship occurs when the fungus invades the roots of a tree or other plant and – through the absorptive capability of the fungus – extracts minerals from the soil and brings them into the host plant. The fungus obtains vitamins and other organic materials from the tree in exchange. Some mycorrhizal relationships are specific between a plant and a fungus.
Some lawn mushrooms are edible and some are toxic. Unless you are a mushroom expert and can specifically identify the mushroom, the best rule to follow is: “Never eat anything that grows in your lawn.” Children should be given this message very clearly.
There are no fungicides registered for mushroom control in lawns. The reason for this is that none have been found to be both effective and safe to use by the home gardener. Mushrooms usually tend to be located in certain areas of the lawn. Your best management options are: (1) rake the affected lawn area daily to break up any new mushrooms, and (2) gather the mushrooms daily before the children go out to play. The mushrooms can be discarded with your green waste recycle. Remember, however, that getting rid of the mushrooms does not destroy the fungus. The mushrooms represent ten percent or less of the total fungus biomass in the soil.