Title: Pythium root rot
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00066889/00001
 Material Information
Title: Pythium root rot
Series Title: Plant Pathology Fact Sheet PP-25
Physical Description: Book
Language: English
Creator: Elliot, Monica L.
Simone, Gary W.
Affiliation: University of Florida -- Florida Cooperative Extension Service -- Department of Plant Pathology -- Institute of Food and Agricultural Sciences
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 2001
Spatial Coverage: North America -- United States of America -- Florida
 Record Information
Bibliographic ID: UF00066889
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text

Plant Pathology Fact Sheet

Pythium Root Rot
Monica L Elliott, Associate Professor, Ft. Lauderdale Research and Education
Center, University of Florida, 3205 College Ave, Ft. Lauderdale, Fl 33314and
Gary W. Simone, Professor Emeritus, Plant Pathology Department, University of
Florida, Gainesville, Florida, 32611. Revised April 2001
Florida Cooperative Extension Service/ Institute of Food and Agricultural Sciences/ University of Florida/ Christine Waddill, Dean


Cultural Controls

Turfgrasses Affected
All warm-season turfgrasses.


Symptoms may appear at any time of the
year, but they will always be associated with
wet soil conditions either from excessive rain-
fall or irrigation. Poor drainage conditions will
compound this problem.


This is a root rot disease. The symptoms
observed on the leaves are the result of fungal
activity on the root system. Aboveground
symptoms are typically a nonspecific decline
in turf quality. Small or large turf areas will
become a general yellow, light green or brown
color and gradually decrease in density (thin-
ning). However, the turf seldom dies from
Pythium root rot, and no distinct patches are

Roots appear thin with few root hairs
and have a general discoloration but are not
black and rotted as they are with take-all root
rot. Microscopic examination of affected roots
will determine if Pythium spp. are associated
with the symptoms.

Pythium spp. are naturally present on
warm-season turfgrass roots. The triggers for
disease are wet soil conditions and stressed
turfgrass. To prevent the disease, especially
during low rainfall periods, improve drainage
and reduce irrigation. Avoid irrigation man-
agement that maintains constantly wet soil.

During periods of high rainfall, incorpo-
rate the following techniques into your man-
agement program. Mow the turfgrass at the
correct height and as often as necessary so that
only one third (1/3) of the leaf tissue is removed
during any one mowing event. It may be nec-
essary to raise the mowing height during peri-
ods of conducive weather. Improper mowing
is a major stress on turfgrass.

Balance nitrogen applications with equal
amounts of potassium. Extra potassium may
be useful in late summer and early fall for those
areas that are routinely affected by Pythium
root rot. Either use a slow-release potassium
source, or apply a quick-release source more
frequently. If the disease does occur, it may be
beneficial to apply nutrients foliarly since the
roots are not functioning efficiently.

Chemical Controls

azoxystrobin, chloroneb, ethazol,
fosetyl-Al, mefenoxam, propamocarb.

Pythium spp.


To increase effectiveness, these fungi-
cides, except for fosetyl-Al, should be either
lightly watered into the root zone or applied
in 5-10 gallons water per 1000 square feet. At
least two applications will probably be re-
quired. Alternate between compounds to
avoid development of fungicide-resistant
strains of Pythium. Please note that, except for
azoxystrobin, these fungicides are specific for
Pythium spp. only. They are not useful

against any other pathogens that attack
turfgrass. Additionally, due to the variation
in Pythium spp. involved with this root rot,
the mefenoxam manufacturer does not recom-
mend its use for root rot control. However,
the product has been reported to be success-
fully used in Florida.

Refer to "Turfgrass Disease Manage-
ment" PPP-64 for explanations of chemical and
cultural controls.

University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs