Chemical controls

Title: Take-all root rot (referred to as Bermudagrass decline on bermudagrass)
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00066895/00001
 Material Information
Title: Take-all root rot (referred to as Bermudagrass decline on bermudagrass)
Physical Description: Book
Creator: Elliot, Monica L.
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 2001
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00066895
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.

Table of Contents
        Page 1
    Chemical controls
        Page 2
Full Text

Plant Pathology Fact Sheet

Take-all Root Rot (referred to as

Bermudagrass Decline on bermudagrass)
Monica L Elliott, Associate Professor, Ft. Lauderdale Research and Education
Center, University of Florida, 3205 College Ave, Ft. Lauderdale, Fl 33314 and
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

Gaeumannomyces graminis var. graminis

Turfgrasses Affected
All warm-season turfgrasses.


The pathogen is naturally present on
turfgrass roots. This disease is primarily ob-
served during the summer and early fall
months when Florida receives the majority of
its rainfall. Prolonged periods of rainfall are
most conducive to this disease. Any stress
placed on the turfgrass will encourage or
worsen the disease.


This is a root rot disease (Figure 1). Be-
cause the roots are affected, they will not be able
to efficiently obtain water or nutrients from the
soil, nor will they be able to store the products
from photosynthesis. Symptoms observed on
the leaves are the result of pathogen activity on
the root system. The fungus does not attack

Initial activity of the fungus on the roots
will only be observed by looking at the roots.
If the turfgrass is not stressed or under low lev-

els of stress, leaf symptoms may never be ob-
served. However, under high stress conditions,
symptoms will begin to appear on the leaves.
By the time the leaf symptoms appear, the
pathogen has been active on the roots for at least
2-3 weeks, probably longer.

Initial symptoms above-ground are ir-
regular, yellow (chlorotic) or light green patches
ranging in diameter from a few inches to a few
feet. Roots will initially be thin and off-white
in color with isolated black lesions. Eventu-
ally, roots will become very short, black and
rotted. Stolons and rhizomes may have black
lesions and, under severe disease conditions,
begin to rot. Entire plants may die resulting in
irregular patches of thinning grass, and if not
controlled, bare patches may develop (Figures
2 and 3). Using a microscope, black strands of
fungi (runner hyphae) will be present on out-
side of roots, stolons and rhizomes, as will spe-
cial structures called hyphopodia.

Cultural Controls

This disease is very difficult to control
once the aboveground symptoms are observed.
Therefore, measures that prevent or alleviate
stress are the best methods for completely con-
trolling the disease or at least decreasing the
potential damage. Stress on turfgrass can re-
sult from many factors and are addressed be-


The turfgrass must be mowed at the cor-
rect height during the summer (Figure 4). It
may even be necessary to raise the mowing
height during periods of conducive weather.
The turfgrass must be mowed as frequently as
necessary so that only one third (1/3) of the leaf
tissue is removed during any one mowing
event. Scalping the grass damages the grow-
ing point, especially of St. Augustinegrass.

Balance nitrogen applications with equal
amounts of potassium. For every pound of ni-
trogen applied, an equal amount of elemental
potassium (K) should be applied. Slow-release
nitrogen and slow-release potassium sources
should be used. Avoid nitrate-nitrogen prod-
ucts and quick-release urea products (e.g., un-
coated urea). If slow-release potassium is not
readily available, then apply quick-release po-
tassium to the turfgrass between nitrogen ap-
plications. Extra potassium may be useful in
late summer and early fall. Apply micronutri-
ents, especially manganese. Micronutrients
should be applied in the sulfate form as foliar

When the disease is active, frequent fo-
liar (leaf) feeding of all nutrients (N, P, K and
micronutrients) in small amounts will be nec-
essary if the root system is severely damaged.
The roots are not functioning properly, and so
will not be able to efficiently obtain nutrients
from the soil.

Do not apply lime to the turfgrass. If you
are growing centipedegrass, it is acceptable to
apply elemental sulfur or iron sulfate to lower
the soil pH below 5.5. Do not do this with other

Apply herbicides only as needed and
according to the label. St. Augustinegrass is
especially sensitive to herbicides. Even when
herbicides are applied correctly, there will be
some stress placed on St. Augustinegrass.

Avoid herbicides by learning how to manage
the turfgrass to limit weeds!

Chemical Controls

azoxystrobin, myclobutanil,
propiconazole, thiophanate methyl,

These systemic fungicides are not as
effective as the use of cultural controls once
the disease symptoms are observed. These
fungicides may be useful when used preven-
tively. This means they must be applied prior
to symptom development. Start applying the
fungicides at least one month prior to when
you normally observe aboveground symp-
toms. Continue applying once a month until
the weather is no longer conducive for dis-
ease development. It is beneficial to lightly
water-in these fungicides, but it must be done
immediately after application.
Refer to Turfgrass Disease Manage-
ment" PPP-64 for explanations of chemical and
cultural controls.


Figure 1. St. Augustin
to Take-all Root Rot..

rigure L.canry avove-grounu symptoms oi
Take-all Root Rot.

rlgure 3. severe symptoms euet
all Root Rot.

Figure 4. Healthy bermudagrass (green strip
at top) cut at the correct height compared to
severely diseased bermudagrass (bottom) cut
too low.

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