White Patch
[Melanotus
phillipsii]
SYMPTOMS
White
patch, also known as white blight, is primarily a disease of tall fescue in
transition zone areas. The disease develops during periods of hot, humid
weather and is most damaging to new plantings in the first year or two after
establishment. Symptoms appear in white circles or patches up to 1 foot in
diameter, and small white or tan mushrooms (about 1/4 inch in diameter) are
produced directly on the blighted leaves. White patch is most damaging in tall
fescue that is under-irrigated or deficient in nitrogen or other essential
nutrients.
|
white patch mushrooms in tall fescue
|
Characteristic
|
Description
|
|
Host
Grass Species
|
tall
fescue
|
|
Month(s)
with symptoms
|
May to
September
|
|
Stand
Symptoms
|
patches
(4 inches to 3 feet)
|
|
Foliar
Symptoms - Location/Shape
|
blighting
of entire leaves
|
|
Foliar
Symptoms - Color
|
white
|
|
Root/Crown
Symptoms
|
none
|
|
Fungal
Signs
|
mushrooms
|
Note: Still not
sure if this is the right disease? The Turfgrass Disease
Identification program may be helpful. Or consult the experts at the Turf
Diagnostics Lab. Check the TurfFiles glossary for definitions
of unfamiliar terms.
FACTORS
AFFECTING DISEASE DEVELOPMENT
The white
patch pathogen is most active during the summer when humidity is high and night
temperatures are above 70°F. Stands of tall fescue that are under-fertilized,
under-irrigated, heavily trafficked, or under other forms of stress are most
prone to this disease.
CULTURAL
CONTROL
Apply 3 to 4
lbs N per 1000 ft2 to tall fescue landscapes annually to maintain
optimal growth and density. Approximately 2/3 of this nitrogen should be
applied in the fall, with the remainder applied in the spring prior to May 1.
Perform an annual soil test to ensure that soil pH and nutrient levels are
optimal. Mow tall fescue regularly to a height of 3” to 3.5”. Use deep and
infrequent irrigation to prevent drought stress and minimize leaf wetness
periods. Irrigate to wet the entire root zone, and then re-apply as needed when
the root zone has become dry.
CHEMICAL
CONTROL
Infestations of white patch are
rarely severe enough to warrant fungicide applications. No fungicides are
labeled for control of white patch, but azoxystrobin (Heritage) and flutolanil
(ProStar) have shown some activity against the disease.
Note:
Recommendations of specific chemicals are based upon information on the
manufacturer's label and performance in a limited number of trials. Because
environmental conditions and methods of application may vary widely,
performance of the chemical will not always conform to the safety and pest
control standards indicated by experimental data. The order in which brand
names are given is not an indication of a recommendation or criticism.
Recommendations for the use of
agricultural chemicals are included in this publication as a convenience to the
reader. The use of brand names and any mention or listing of commercial
products or services does not imply endorsement by North Carolina State
University or discrimination against similar products or services not
mentioned. Other brand names may be labeled for use on turfgrasses. Individuals
who use agricultural chemicals are responsible for ensuring that the intended
use complies with current regulations and conforms to the product label. Be
sure to obtain current information about usage regulations and examine a
current product label before applying any chemical. For assistance, contact
your county's Cooperative Extension agent.
© North Carolina State University. This information sheet was prepared
by Lane P. Tredway, Gail G. Wilkerson, Bridget R. Lassiter, Jenifer J.
Reynolds, and Gregory S. Buol. Departments of Plant Pathology and Crop Science,
College of Agriculture & Life Sciences, North Carolina State University.
Prepared April 29, 2008. Available on-line at
www.turffiles.ncsu.edu. This publication was made possible through a grant
provided by the Center for Turfgrass Environmental Research & Education
(CENTERE) whose purpose is to support worthwhile projects that will benefit
both the private sector and the public, and protect the environment.