Although spores from soil fungi are microscopic, they grow into what’s known as hyphae, which are thin tubular threads. When these threads accumulate into a mass, it's called a mycelium. Under the right conditions, hyphae can grow so quickly that it’s been estimated the amount of hyphae produced in only one day by just one soil fungus would be almost a mile long, according to the Wayne’s World website. While many soil fungi are beneficial, others are harmful, so it’s important to recognize the symptoms of a bad fungus to treat a problem.
Soil fungi perform important functions linked to water dynamics, disease suppression and nutrient cycling. They serve a fundamental role as decomposers in a soil’s food web. These fungi convert organic materials that are hard to digest into forms that are usable for organisms. Hyphae, the main form of vegetative growth, bind soil particles to create stable aggregates that help to increase water infiltration and the holding capacity of soil water.
Soil fungi fall into three functional groups, depending on the way they get their energy. Decomposers convert dead organic matter into small molecules such as carbon dioxide. Mutualists develop beneficial relationships with plants by colonizing plant roots and helping plants get nutrients such as nitrogen and phosphorus from the soil. Pathogens or parasites are mostly considered detrimental and reduce plant production or can even cause the death of a plant. These soil fungi include Phyium, Verticillium and Rhizoctonia.
Symptoms of Common Soil Fungi
Fusarium wilt and Verticillium wilt are two of the most common soil fungi that infect grass, plants and trees. A main symptom of Fusarium wilt is a brown discoloration on a plant’s vascular system. When the bark of a main stem (slightly above the soil line) is cut and then peeled back, this brown discoloration of the plant’s vascular tissue can be clearly seen. Verticillium wilt, which afflicts many types of vegetable plants, can be detected by leaves that are discolored and limp. These signs can be seen on either individual branches or on an entire plant.
There are several ways of controlling soil fungus and masking its symptoms. First, it’s important to aerate soil in an affected area and then add sterile topsoil or compost. Next, soil should be well-watered. In severe infections it may be necessary to dig out about 4 to 6 inches of soil and to replace it, according to Lawn Care.net. Masking symptoms can be done with frequent mowing and feeding a lawn, which makes a lawn appear greener.
Although most people link all parasitic fungi with disease, several types of parasitic fungi help to control diseases. Some fungi eat insects that kill plants. An example is the type of fungi that traps nematodes, which are wormlike organisms living as parasites on plants and animals.