Favourable fungi on lawns

Fungi are well known for their negative impact, but there are also favourable fungi on lawns.

Fungi are responsible for the most serious and economically impactful lawn diseases, but the reality is that most fungi are neutral or even favourable to the lawn.

The genera Penicillium, Aspergillus, Trichoderma, Gliocladium, Fusarium, Mucor and Mortierella have positive effects on turf.

Fungi may take their food from organic matter in the soil or they may take it from the plant. Their food source does not define whether their relationship with plants is parasitic or symbiotic.

The use of fungicides normally affects many genera and therefore can lead to imbalances, and it is in the face of these imbalances that we see obvious disease problems in the turf.

A disease is an imbalance in the rhizosphere.

Apart from the interactions between fungi that maintain equilibrium, there are very specialised fungi with impressive symbiotic associations such as mycorrhizae. Mycorrhizal fungi benefit from the sugars in plants, and these increase the nutrient availability such as phosphorus or a better water supply.

Research has seen possible significant symbiotic benefits of various fungi, particularly on Poa pratensis and Agrostis stolonifera. - By DR. WILLIAM A. TORELLO - .

Actinomycetes are more closely related to bacteria, but grow more like a fungus. Their growth rates are much slower than other micro-organisms and they are generally more abundant in drier soils with high organic matter content or in high temperature soils. They do not tolerate low soil pH (less than 5.0).

The main genera of soil actinomycetes include Streptomyces, Nocardia, Micromonospora and Actinoplanes.

In particular, they are well adapted to the decomposition of the most resistant plant polymers such as cellulose, hemicellulose and lignin, as well as chitin from fungal and insect polymers. Because of this, actinomycetes play an important role in the formation of humus in soils.

Actinomycetes help to suppress soil-borne diseases of turf. Many of the antibiotic compounds in actinomycetes affect the growth and development of pathogenic fungi. Composts are particularly rich in pathogen-suppressing actinomycetes. The beneficial effect of amending soils with compost is partly due to the disease suppressive properties of actinomycetes.