Slime Mold
[Myxomycetes
spp.]
SYMPTOMS
Many
small, round pustules are observed on the turfgrass leaves in small patches.
The patches develop very quickly, usually overnight. The pustules may be
purple, white, gray, yellow, or orange in color. The slime mold organisms do
not infect the turf or cause direct harm, but they can cause mild yellowing of
the leaves due to their shading effect. Slime molds are unsightly but are not
considered harmful.
|
slime mold pustules
|
Characteristic
|
Description
|
|
Host
Grass Species
|
all
|
|
Month(s)
with symptoms
|
April
to September
|
|
Stand
Symptoms
|
spots,
patches (4 to 12 inches)
|
|
Foliar
Symptoms - Location/Shape
|
no
distinct leaf symptoms
|
|
Foliar
Symptoms - Color
|
all
|
|
Root/Crown
Symptoms
|
none
|
|
Fungal
Signs
|
pustules
|
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
Slime mold spores survive in the
soil and thatch. During warm, wet weather the spores germinate and develop into
a colorless, slimy mass that grows over the soil and nearby plant parts during
wet weather. The pustules observed on turfgrass leaves are reproductive
structures that contain numerous spores.
Flushes of slime mold growth are
often observed after heavy rain storms that were preceded by long periods of
dry weather.
CULTURAL
CONTROL
Slime mold pustules typically
disappear after 2 to 3 days, therefore, no control practices are needed. If the
growth is particularly unsightly, the pustules may be removed by brushing,
mowing, or washing the turf.
CHEMICAL
CONTROL
Fungicides are available for
slime mold control but should only be used in severe cases.
|
Fungicide
|
Efficacy (1)
|
Resistance Risk (2)
|
Class (3)
|
Products (4)
|
|
mancozeb**
|
++
|
1
|
dithiocarbamate
|
Fore, Dithane, Protect
|
|
** Not for application to
residential lawns.
|
|
Footnotes:
|
|
(1)
|
Efficacy Codes:
|
|
++++
|
excellent control when
conditions are highly favorable for disease development
|
|
+++
|
good control when disease
pressure is high, or excellent control when disease pressure is moderate
|
|
++
|
good control when disease
pressure is moderate, excellent control when disease pressure is low
|
|
+
|
good control when disease pressure
is low
|
|
0
|
does
not provide adequate control under any conditions
|
|
?
|
cannot be rated due to
insufficient data
|
|
(2)
|
Resistance Risk:
|
|
1
|
Rotating and tank-mixing not necessary,
but recommended to avoid potential side effects from continuous use of same
chemical class.
|
|
2
|
Rotate to different chemical
class after 3-4 applications; tank-mixing not necessary.
|
|
3
|
Rotate to different chemical class
after 2-3 applications; tank-mixing not necessary.
|
|
4
|
Rotate to different chemical
class after 1-2 applications; tank-mixing not necessary.
|
|
6
|
Rotate to different chemical
class after 1-2 applications; tank-mixing with low or moderate risk product
recommended.
|
|
9
|
Rotate to different chemical
class after EVERY application; tank-mix with low or moderate risk product for
EVERY application.
|
|
(3)
|
Continual use of fungicides with
similar control mechanisms (modes of action) can result in fungi that are
resistant to some chemicals. Poor or ineffective disease control can be
expected when this occurs. Managers can reduce the chances of this happening
by mixing or alternating fungicides belonging to different chemical classes.
|
|
(4)
|
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. When more than one brand name exists for an agricultural
chemical, the name of brand that first came onto the market is listed first.
Otherwise, brand names are listed in alphabetical order. 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 Fred Yelverton, Gail
G. Wilkerson, Leon Warren, Travis Gannon, and Gregory S. Buol. Department of
Crop Science, College of Agriculture & Life Sciences, North Carolina State
University. Prepared November, 3, 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.