|
back
| home
University
of Rhode Island GreenShare Factsheets
Cultural
Practices to Reduce Lawn Diseases
• Prepare
the site well. • Remove stumps,
construction materials and other debris. • A minimum
depth of good topsoil is 6 inches. • Adjust
levels for good surface drainage. •
Test soil pH and adjust to 6.0-7.0 with
ground limestone. • Cultivate to
provide a uniform, fine, firm (but not compacted) seed bed
for seed or sod. • Apply starter
fertilizer before planting. See GreenShare Factsheet on Developing a Fertility Program for
Lawns for more information • Choose seed
or sod carefully. Inspect sod for diseases, weeds, insects,
overheating, etc. Choose good quality, pathogen-free seed.
Disease
and insect-resistant (endophytic) cultivars are now available and
should be included in blends and mixtures. Increasing the genetic
variability in the lawn will reduce the chance for epidemics
that
kill large areas. See GreenShare Factsheet on Selection
of Turfgrass for more information. Other
landscaping decisions will affect lawn health. Pruning of tree branches
will increase light penetration, allowing better turfgrass growth.
Trees, shrubs, and other plantings should be placed to allow good
air circulation, ensuring that the turfgrass will dry quickly after
rain or dew. In very shady areas, shade-tolerant grass species or
cultivars may survive, but it is preferable to plant other ground
covers. See GreenShare Factsheet on Growing
Turf under Shaded Conditions for more information. Seed
should be planted only in well-prepared soil with good drainage
when temperatures stay in the 60-85 degrees F range to allow rapid
germination and establishment. Keep soil and seed moist, but do
not overwater. Overwatering may result in fungal damping-off diseases.
Fertilizers:
Apply according to recommendations based on a soil test. Excess
nitrogen will cause succulent growth that is more susceptible to
disease. Examples where excessive nitrogen causes enhanced disease
severity include: a)
leaf spot season in early spring, b) brown
patch and Pythium blight during hot,
humid summer weather, c) snow
molds and winter injury if N applications occur just before
dormancy in fall. A deficiency
of nitrogen often encourages some turfgrass diseases; examples are
dollar spot, red
thread, pink patch and rust. Herbicides:
Apply the appropriate herbicides according to the label instructions.
Herbicides can stress lawn grasses and may make them more susceptible
to diseases such as leaf spot. Liming:
Adjust pH with ground limestone according to recommendations
based on soil test results. Some diseases increase at pH extremes
(too high or too low). For example, lime applied late in autumn
can increase pink snow mold. High soil pH may encourage summer
patch. See GreenShare Factsheet on Liming
for more information. Mowing:
• Mowing
wounds the leaf blades (allowing fungal entry) and spreads disease-causing
organisms (pathogens) in turfgrasses. Minimize wounding and
shredding
of turfgrass leaves by keeping mower blades sharp and adjusted
properly. • Mow
when grass is dry. • Mow
lawns at a height of 2.5-3.0 inches, using the maximum height in
hot weather. • Mow
only 1/3 of the total height at each cutting to avoid stressing
the turfgrass. • Don't
"scalp." • Mow
in autumn until the grass stops growing. • Collect
clippings only if they are excessive and during disease outbreaks. • See
GreenShare Factsheet on Mowing for more
information. Watering:
Water is necessary for good plant growth, but too much water floods
the air pores in the soil, depriving roots of oxygen. Roots will
subsequently die. Many disease-causing fungi reproduce by spores
that, like seeds, need water to germinate. Dry leaf blades reduce
disease by not favoring spore germination and infection by fungi.
• Water
infrequently but deeply, to a depth of 6 inches. • Water
early in the day, so the turfgrass will dry quickly. • Night watering after
dew appears may help with water conservation but is not recommended
on hot, humid nights because it can increase
some diseases, especially brown patch and Pythium blight. • Avoid light, frequent
sprinklings and do not water in the late afternoon or early
evening. • In
very hot, dry weather, daily watering may be necessary to prevent
wilt and dormancy. Areas along walls, sidewalks and driveways
may
also need to be watered more frequently. • See
GreenShare Factsheet on Efficient Watering
of Turf for more information. Thatch:
Thatch is an accumulation of decaying organic residues between
the green portion of the grass plant and the soil. When thatch is
more than 1/2 inch thick, it reduces nutrient and water absorption
and harbors insect pests and disease-causing pathogens. Prevent excess
thatch formation by avoiding excessive fertilizer, insecticide,
herbicide and fungicide use. Excessive thatch can only be mechanically
removed. Coring frequently on 2 inch centers is the most effective
means. See GreenShare
Factsheet on Thatch for more information. Compaction:
In areas of poor turfgrass growth due to compaction, coring
will help aerify the soil and improve turf quality. Compaction is
associated with many turfgrass diseases including necrotic
ring spot, red thread, rust
and summer patch. Adapted
from the University of Massachusetts Extension, 1999
Pesticides
are poisonous! Read and follow all safety precautions on labels.
Handle carefully and store in original containers out of reach
of children, pets or livestock. Dispose of empty containers
immediately, in a safe manner and place. Pesticides should never
be stored with foods or in areas where people eat.
When trade names are used for identification, no product endorsement
is implied, nor is discrimination intended against similar materials.
Be sure that the pesticide you intend to use is registered for
the state of use.
The user of this information assumes all risk for personal injury
or property damage.
For more
information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
University
of Rhode Island Cooperative Extension provides equal program
opportunities.
|