Rust
[Puccinia
spp.]
SYMPTOMS
Early
symptoms include small, yellow flecks that develop on the leaves and stems. The
flecks expand over time into raised pustules, orange or red in color, that
rupture to release powdery masses of yellow, orange, or red spores. Infected
plants become yellow and are more susceptible to environmental stress. Heavily
infected areas become thin and exhibit clouds of orange dust (rust spores) when
the foliage is disturbed. The rust pustules on infected leaves turn black
during the fall in preparation for overwintering.
|
rust blisters
|
Characteristic
|
Description
|
|
Host
Grass Species
|
Kentucky
bluegrass, tall fescue, St. Augustinegrass, zoysiagrass
|
|
Month(s)
with symptoms
|
March
to June, September to November
|
|
Stand
Symptoms
|
irregular
distribution across turf stand
|
|
Foliar
Symptoms - Location/Shape
|
dieback
from leaf tip, blighting of entire leaves, or no distinct leaf symptoms
|
|
Foliar
Symptoms - Color
|
yellow
or orange
|
|
Root/Crown
Symptoms
|
none
|
|
Fungal
Signs
|
blisters
on leaves
|
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
Rust fungi
survive the winter in living plant tissue from which new spores are produced in
the spring. Spores produced in the spring, summer, and fall are spread by the
wind, germinate on the leaves, and infect new tissue. Extended periods of leaf
wetness are required for the spores to germinate and for the disease to develop
rapidly.
Rust diseases are most severe in
turf that is growing slowly due to adverse weather conditions or inadequate
management. Low light intensity, inadequate fertilization, drought stress, and
infrequent mowing encourage rust development.
CULTURAL
CONTROL
Plant
rust-resistant turfgrass varieties whenever possible to reduce injury from this
disease. Select cultivars based on regional trials and University
recommendations. When planting cool-season turfs, use blends and mixtures of
multiple species and/or varieties whenever possible. Plant shade tolerant
grasses and raise mowing heights in heavily shaded areas.
Prune trees and remove unwanted
undergrowth to improve air movement and reduce prolonged leaf wetness. Mow the
turf on a regular basis, removing no more than 30 to 40 percent of the foliage
in one mowing. Collect and dispose of clippings taken from infected areas to
slow the spread of rust.
Fertilize to meet the nutritional
needs of the turf. Submit a soil sample for analysis on a regular basis and apply
recommended amounts of phosphorus, potassium, and lime. Apply nitrogen based on
University recommendations.
Water deeply but infrequently to
encourage deep rooting and reduce drought stress and extended periods of leaf
wetness. Avoid watering the turf before sunset or after sunrise.
CHEMICAL
CONTROL
Fungicides can be used on a
preventative or curative basis for rust control. Susceptible turfs should be
monitored regularly for rust development during periods of cool and cloudy
weather.
|
Fungicide
|
Efficacy (1)
|
Resistance Risk (2)
|
Class (3)
|
Products (4)
|
|
propiconazole
|
++++
|
6
|
DMI
|
Banner MAXX, Propiconazole G-Pro, Propiconazole Pro,
Quali-Pro Propiconazole, Savvi, Spectator
|
|
triadimefon
|
++++
|
6
|
DMI
|
Bayleton
|
|
azoxystrobin
|
++++
|
9
|
QoI
|
Heritage
|
|
mancozeb**
|
+++
|
3
|
dithiocarbamate
|
Fore, Dithane, Protect
|
|
chlorothalonil**
|
+++
|
3
|
nitrile
|
Daconil, Chlorostar, Echo, Manicure
|
|
thiophanate-methyl
|
?
|
9
|
benzimidazole
|
3336, Fungo, Systec, T-Storm
|
|
maneb**
|
?
|
3
|
dithiocarbamate
|
Pentathlon
|
|
thiram**
|
?
|
3
|
dithiocarbamate
|
Spotrete
|
|
myclobutanil
|
?
|
6
|
DMI
|
Eagle
|
|
triticonazole
|
?
|
6
|
DMI
|
Trinity
|
|
fluoxastrobin
|
?
|
9
|
QoI
|
Disarm
|
|
pyraclostrobin
|
?
|
9
|
QoI
|
Insignia
|
|
trifloxystrobin
|
?
|
9
|
QoI
|
Compass
|
|
** 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 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.