Lawn Care/Basics
for Homeowners-Lawn Care/Pest Control/Fungus
Moss, algae, and fungi (like mushrooms) can all can be harmful parasitic plants
within your turf. They may appear when conditions needed to grow a thick, healthy
lawn are not met. Although these plants are not harmful, some may wish to eliminate
them. The real challenge is to eliminate the conditions that encourage them.
Fungi feed on decaying material in the thatch or soil, but never do any damage
to the turf itself.
Mushrooms are caused by a large number of different fungi. They
are sensitive to moisture and so they normally appear during periods of heavy rainfall or
on very heavily irrigated turf. In almost all cases, mushrooms will disappear when
moisture levels return to normal, and regular mowing is about all the control required to
manage the appearance problem they can cause. Some of the fungi that cause mushrooms are
sensitive to fungicides, but control is difficult, expensive, and the results are usually
less than desirable.
Algae are unicellular or multicellular threadlike green plants
that form a thin dense green scum over the soil surface. This scum forms a tough
black crust when dry which acts as a barrier impending the entrance of water
and nutrients into the soil. Algae tend to grow the best in compacted, waterlogged
soils and during warm, sunny, humid conditions.
Algae in turfgrass
Mosses are green plants with leaves arising from all sides
of a central axis. Mosses may grow erect or along the ground. They typically
form a thick green mat at the soil surface. Conditions favoring the growth of
mosses include low fertility, poorly drained soils, high soil acidity, excessively
wet soils, soil compaction, excessive
thatch or a combination of these factors
that add up to thin or weak turf. Mosses thrive in cool, moist, shaded locations;
such as the north side of buildings and wooded areas.
Physical or chemical removal of these pests will only be temporary unless
growing conditions are improved. In some areas you may choose to use a mulch
cover (pine straw, bark, etc.) or plant a shade-tolerant ground cover instead
of turfgrass. The only permanent control of fungus is to correct the conditions
unfavorable to turfgrass growth. Here are some tips:
- Maintain good soil fertility. Lawns should be fertilized
at least once per year. September is the preferred month.
- Improve drainage. Soils that are constantly wet because of poor drainage should
be contoured so that water will drain away from the wet areas of the lawn. In some lawns,
tile drainage may be necessary to correct wet conditions. However, tile may be ineffective
in heavy soils unless special precautions are taken to facilitate water movement to the
tile system.
- Improve air circulation. Low-branched trees may be the cause of poor air
circulation as well as dense shade. Lawns surrounded by buildings and tall vegetation with
limbs close to the ground will require considerable effort to provide adequate air
circulation necessary for the growth of a good lawn.
- Provide more light. In some cases a choice between trees
and a good lawn must be made. If the lawn is completely shaded, removal of
some of the least desirable trees may be the only answer in order to grow
a good turf. Other times, removal of low branches and thinning the crowns
of trees will allow enough light to reach the ground surface so that a good
turf can be produced. If you are not willing to remove enough vegetation so
that direct sunlight reaches the ground during part of the day, consider substituting
a ground cover for grass. In addition, plant grasses which are shade tolerant.
- Irrigate lawn in the morning. Fungus grows the best in dark, damp, cool places.
By irrigating in the early part of the day you give
the sun a chance to kill most fungus that would grow if you watered in the evening.
- Loosen compacted soil. The blackened algae layer found in some lawns inhibits gas
flow from the air to the soil and vice versa and also reduces water infiltration.
Compacted soil may be loosened by cultivation and addition of large amounts of organic
matter if the lawn is to be renovated. Aerification
with a machine that removes plugs of soil will help a lawn where it is undesirable to
disturb the soil surface.
If this is too much work to complete at once, there are some chemical control options
available. However, these chemicals only offer a temporary solution. Permanent fungus
control can only be achieved by the tips mentioned above.
- Algae may be controlled with copper sulfate at the rate of 2 to 3 ounces per 1,000
square feet or one teaspoon in 8 gallons of water. An application of 5 to 10 pounds of
ground limestone per 1,000 square feet prior to reseeding will help to inactivate the
copper sulfate that may be toxic to grass seedlings. Punch holes in the algae crust or
remove the crust entirely to allow turf recovery in these areas. Prepare a new seedbed and
replant if large bare areas exist.
- Moss may be controlled with copper or ferrous sulfate sprayed at 5 ounces per 1,000
square feet in 4 gallons of water. Applying concentrated amounts (10 ounces per 1,000
square feet) of ferrous ammonium sulfate to the moss spots when the moss is damp offers
another means of control. Ferrous ammonium sulfate should not be watered in. An
application of 5 to 10 pounds of ground limestone per 1,000 square feet prior to reseeding
will help to inactivate the copper sulfate that may be toxic to grass seedlings. Physical
removal of the moss by raking may be needed to allow recovery in these areas. Prepare a
new seedbed and replant if large bare areas exist.
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Lawn Care/Basics
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