 |
| GRAY
SNOW MOLD ON TURFGRASS |
|
 |
|
Introduction
Winter diseases of turfgrasses are often associated with
melting snow or cold, wet periods. Bluegrasses (Poa
sp.), fescues (Festuca sp.), and ryegrasses (Lolium
sp.) may be attacked, but bentgrasses (Agrostis
sp.) are most susceptible. Two diseases, Typhula blight (gray
snow mold) and Pink snow mold, are common in New York,
and may occur singly or side-by-side. Since different
fungicides may be used to control each of these diseases,
it is necessary to distinguish between them.
Symptoms
Figure 1: |
|
Figure 2:
|
|
Gray snow mold (Typhula
blight) is caused by Typhula incarnata and
related species. It is a true snow mold and appears as
roughly circular bleached patches up to 60 cm in diameter.
Soon after the snow melts, the infected grass may be
matted and surrounded by a white to gray halo of fluffy
fungal growth. Examination of the diseased plants reveals
tiny tan or brown pea-like structures (sclerotia) on or
imbedded in infected leaves. The severity of the disease
will vary. It is particularly severe when turf has been
subjected to a prolonged, deep, compacted snow cover.
Although the disease is unsightly, it rarely kills the
grass.
Disease Cycle
Disease cycle of gray snow
mold.
(Provided by Compendium of
Turfgrass Diseases, 2nd edition, APS Press) |
Control Strategies
Development of gray snow molds can be reduced via
cultural methods. Avoid late fall applications of
fertilizer that would stimulate succulent growth. Such
growth is very susceptible to infection. Also continue to
mow turf as long as it continues to grow in the fall and
avoid compacting snow over the lawn. Where snow molds
have caused damage, rake the matted grass in order to
encourage new spring growth. If reseeding areas where
these diseases have been a problem, use disease resistant
turfgrass varieties.
If snow molds have been severe or wide-spread in past
years, or if susceptible varieties or species are being
grown, a preventative fungicide program may be used.
Fungicide applications should be made in late autumn just
before permanent snow cover is expected and, if possible,
during a mid-winter thaw. Fungicides containing the
active ingredients iprodione, fenarimol, propiconazole,
quintozene, and triadimefon can be used to manage either
disease. Typhula blight can also be managed via
fungicides containing chlorothalonil, chloroneb, and
thiram. Where multiple applications are required,
alternate the use of 2 or 3 recommended fungicides. In
all cases, read and follow pesticide label directions.
Last updated, KLS, 8/99
This publication contains pesticide recommendations.
Changes in pesticide regulations occur constantly, some
materials mentioned may no longer be available, and some
uses may no longer be legal. All pesticides distributed,
sold, and/or applied in New York State must be registered
with the New York State Department of Environmental
Conservation (DEC). Questions concerning the legality and/or
registration status for pesticide use in New York State
should be directed to the appropriate Cornell Cooperative
Extension Specialist or your regional DEC office. READ
THE LABEL BEFORE APPLYING ANY PESTICIDE.
__________________________________________________________________________________
The Plant Disease Diagnostic
Clinic at Cornell University is located at 334
Plant Science Building, Ithaca, NY, 14853. Phone:
607-255-7850, Fax: 607-255-4471, Email: kls13@cornell.edu
|