Question:

Why has my well manicured lawn has been invaded by disease?

Irrigate Properly

When you water your lawn, water it only in the morning. The best time to water is between 6:00 and 9:00 am. Winds are usually low, temperatures are usually cool and the sun has not risen high enough to speed evaporation. Thus, the water percolates into the soil rather than evaporating (afternoon watering) or lying on the grass' surface (evening watering). Evening watering on a regular basis is asking for trouble. Fungi thrive on cool temps and moisture.

Good Drainage ...

Turf diseases can usually be traced to one of four causes--improper watering, poor drainage, improper mowing and over-fertilization. Poorly drained soils allow water to stand. Standing water then invites algal and some fungal pathogens to attack the lawn. Encouraging good drainage means building up the organic material in the soil and aerating regularly.

Lawn Fungi

Most lawn diseases are caused by fungi, a non-flowering plant that cannot produce its own food through photosynthesis. Thus, you will never see a green fungus. Green, slimy material is most likely an algal agent caused by overly moist, nutrient rich soils.

Turf Disease

Turf diseases can display symptoms that might be mistaken for other problems. Some diseases, such as take all patch, display the same symptoms as grub damage. If the grass does not have any roots and you do not see grubs in the soil, chances are good that take all patch is the cause. Certain diseases of St. Augustine and Fescue also resemble insect damage. Careful inspection of the soil, the roots, the stems and the leaves at the margin--the area bordering healthy grass--is the key to diagnosing the disease. Telltale signs of disease include yellowing leaves that detach easily from the sheath, blotchy or spotty leaves, greasy, slimy or moldy appearance, white or grey substance covering the stems or leaves, unusual rubbery or fleshy substance growing across the soil surface and a bad smell.

Incurable Problems

We've stressed good management, and you've followed that advice. You've properly followed a regimen of good mowing, watering and fertilization practice and the turf is performing. Then disaster strikes and a disease devastates the turf.

By definition, a high maintenance, high performance turf is a high cost and high risk turf. The more time and money you spend on the lawn, the more likely you are to face lawn disease. Lawns are monospecific cultures. A single variety or a single species of organism is living in a large area exposed to natural forces. Nature detests monospecificity as much as she detests a vacuum. While nature can be delayed and sometimes even thwarted with vigilance and good decision-making, sooner or later nature will have her way. Be prepared--if you spend a lot of time and money on the lawn, you'll have to spend a lot of effort repairing the damage.

Healthy Root Growth

Fertilizers that are high in nitrogen promote shoot growth. A lush, green canopy then invites disease. To promote healthy turf, promote root growth. Use complete fertilizers in recommended amounts. Promote soil tilth by amending the soil with organic matter, and water the lawn so that soil is moistened to the desired root depth.

Mushrooms

Science has since shown that the mushrooms are the manifestation of a massive fungus development, located near the soil surface. The fungus feeds on buried and decaying organic material. The fungus forms a hydrophobic (water proof) layer that prevents water and nutrients from reaching grass roots. The grass wilts and dies in an outwardly expanding circle, but often returns in the center. The center of the circle is usually greener than the rest of the grass, because the fungus completely breaks down that organic material, dies itself and makes all of the nutrients available for the grass. Some limited success has been gotten by performing a deep core aeration, followed by a drench of fungicide containing flutolanil or quartenary ammonium compounds. The deep plugging punches holes in the waterproof layer and this allows the fungicide to come into contact with enough of the fungus to control it. This doesn't always work, and it can be expensive and time consuming. Eventually, the fungus will break down all of the material in the soil and go away by itself. This can take anywhere from 1 to 8 years, depending on the amount of material it has to work with. The only other alternative is a massive excavation to remove all of the woody material in the soil.