Fungi are plants that lack chlorophyll and therefore are unable to produce their own food. To feed and survive, the fungi needs to obtain food from either dead organic matter (dead leaves and excessive thatch) or find and take over a host plant.
Fungi spread through spores, which are easily transferred through wind, rain, mowing and simply walking through a fungi outbreak. Once transferred, the spore penetrates into the host plant, feeding and growing until it has taken over the host.
During peak fungus season a fungus can produce and discharge up to 100,000 spores an hour.
For Fungus to spread and be present there needs to be three main factors:
a) Host, living or dead organic matter (thatch and leaves)
b) the Right Environment, such as a shaded, moist environment
c) the Pathogen.
These three factors are also known as the disease triangle. All three must be present for the fungus to grow and spread.
If fungus is present in your lawn, it will present itself in circular, irregular patterns of damage. It will have a clear dead zone where the fungus has fed and a lighter yellow/brown ring around the outskirts where the fungus is spreading.
Be proactive; be on the lookout for damp shaded areas that hold more moisture than other parts of your lawn. These areas may or may not have excessive thatch or other dead organic material. If you have areas that match this description, it is time to treat your lawn. As these pose the greatest threat of an outbreak.
A good rule of thumb is that by the time your azaleas are showing color, you should be able to see very clearly if your lawn has a fungus.
The best way to treat Fungus is to be proactive and treat at the first sign of damp lawn areas and not after the fungus has taken hold. This can be done with a simple application of a systemic fungicide..
A few recommended options are listed below, one liquid hose end, one tank mix, and one granular. With fungicide, you get what you pay for, but some action is always better than none!
Bayer Advanced (Good, Hose End Spray)
Honor Guard (Better, Tank Mix)
Bayer Heritage G (Best, Granular)
If you already have fungus, stop what you are doing and go purchase a topical fungicide and treat the area immediately; be sure not to mow over that area or walk on it. Each area may take several treatments.
Some fungicides function as both preventative and curative, with large application rates for curative treatments. Once the outbreak is controlled, place a fungicide that attacks the roots (systemic) on a schedule to help further outbreaks.
Be sure to check your lawn and treat for fungus prior to any fertilizing/feeding this spring. Most fertilizers contain Nitrogen, which fungus love. If you feed your lawn prior to putting a fungicide down and you have a fungus, that fungus will expand exponentially, which will be disastrous for your lawn.
Armed with this new knowledge, go check your lawn, treat the problem areas or potential at-risk areas, and get to spending more time enjoying your lawn instead of working on it.