To avoid disease, provide the best lawn care you can by giving the grass just the right amount of
water and fertilizer and keeping the soil open and loose.
If grass blades are wet for long periods or you water daily so your soil never dries out, you lawn
more likely to be infected. Water properly (at least ½ inch twice a week) in the early morning so
that the grass blades can dry during the day.
Thatch is a breeding ground for pathogens. Aerate to reduce thatch, relieve compaction, and improve
Necrotic ring spot (NRS) is a perennial disease of Kentucky bluegrass. NRS results in circular or
doughnut-shaped patches of dead grass. Symptoms often develop in late summer. NRS can be controlled
by the use of resistant varieties, which includes ScienTurfic Sod, good turf management
practices, and fungicide applications.
Ascochyta leaf blight has become a common problem on Kentucky bluegrass lawns in Colorado. Large
uniform areas of affected turf will turn straw-colored. Leaves usually start dying back from the
tips. Ascochyta can occur throughout the growing season but is more prevalent in the spring when
there are extended wet periods. The first line of defense against Ascochyta leaf blight is to manage
the turf properly.
Dollar spot, a major turfgrass disease in Colorado, often is confused with Ascochyta leaf blight.
Turfgrass under stress is more susceptible to infection. Proper lawn management, such as aeration,
and proper watering and fertilization will reduce dollar spot problems. Use fungicides only in
situations with recurrent dollar spot problems. Ensure nitrogen levels are sufficient to sustain a
moderate rate of shoot growth.
Heavy rains, prolonged rainy periods, or excess watering often encourage the growth of mushrooms
(toadstools) in home lawns and other turf areas. Most often, the mushrooms will appear randomly
across a new lawn because of the extra water required to get the sod to root in. Once the moisture
in the soil reduces, the mushrooms should stop appearing. Since young children and pets may be
tempted to eat mushrooms, remove the obvious fungal structures by raking, mowing, or hand picking
to avoid the possibility of poisoning or illness.
Mushrooms may grow in a circle around grass forming “fairy rings.” Construction debris, old tree
roots, and stumps encourage their growth. Spring and fall aeration along with several applications
a few ounces of dish washing soap dissolved in a gallon of water on the ring may make the ring less
noticeable. No Fungicides control fairy rings.
Gray and Pink Snow Mold appear as fluffy white to salmon pink mixture of fungal strands & spores
visible at the edge of the patch. Usually 6-24” in diameter throughout the lawn or side-by-side.
Turfgrasses are very prone to diseases when snow or ice cover persists for long periods of time in
the winter, thus trapping moisture and preventing sunlight in the turf. Lightly rake the matted
turf. This will increase air circulation around the grass plants and allow the grass to grow and
fill in. As soon as the soil begins to thaw out, it is a good idea to aerate the turf to
encourage root and rhizome growth.
Small to large areas of the lawn, especially in shady to partial shade locations, show symptoms of
grass being dusted with flour or talc. As the disease progresses, turfgrass blades wither and die.
Powdery mildew is caused by a fungus. It is not considered to be a serious disease on turf, but is
more of an
esthetic problem. Sever outbreaks tend to occur in shaded areas in late spring through fall. High
humidity and temperatures above 60 degrees favor this disease.
Increase sunlight penetration by
pruning trees and shrubs to allow more light to infected areas. Adjust water so that areas prone to
the disease will stay drier. Fungicides can be applied as a preventative before the disease becomes
established. Blades already infected will not benefit from chemical treatments.
Brown patch commonly starts as a small spot and can quickly spread outwards in a circular or
horseshoe pattern up to a couple of feet wide. Often times, while expanding outwards, the inside of
the circle will recover, leaving the brown areas resembling a smoke-ring. The best prevention for
brown patch is to aerate often, reduce shade to effected areas, and follow a fertilization schedule
to help prevent fertilization with excess amounts of nitrogen.
Rust gets its name from the orange, "rusty" appearance it gives leaf blades. Rust tends to flourish
in conditions of morning dew, shade, high soil compaction, and low-fertility. The best way to check
for rust problems is by taking a white tissue or paper towel and rubbing a few grass blades through
it. If an orange color remains, then it's usually rust. The best prevention for rust is to aerate
your lawn, water well in the morning hours, reduce shade to grass, mow more frequently while bagging
the grass, and by following a fertilization schedule to help increase the amount of nitrogen levels
in your lawn.
Red thread is most common to Fescues, Ryegrasses, and Kentucky Bluegrasses during times of moist
and cool weather. Red Thread gets its name from the pinkish-red threads that form around the leaf
blades and bind them together. Eventually, the affected grass will turn brown and the red treads
will be most visible when wet. The best prevention for red thread is to aerate often and remove
thatch. Mowing to proper levels, reducing shade on lawn, and following a fertilization schedule can