Unit V Golf Course management Lesson 9
Lesson 9. Turf Diseases and Controls on Golf
Courses
Some Turf Diseases Are Devastating!
Terms
disease: an abnormal, unhealthy disorder of a plant
caused either by a pathogen or an unfavorable condition
National Science
fungicide: a pesticide used to control a disease caused by Education
Standards, Grades
fungi 9-12
fungus: a type of microorganism producing mycelium and Unifying Concepts
and Processes:
spores without chlorophyll: Most turfgrass diseases are
caused by fungi, which feed on turfgrasses. Systems, order, and
organization
hyphae: the threadlike filaments of the fungus body. Evidence, models
and explanation
infection: the invasion and establishment of a disease-
causing microorganism (pathogen) within a plant. Science as Inquiry:
Understanding about
mycelium: a mass of hyphae. scientific inquiry
nematodes: small and un-segmented roundworms with Abilities to do
scientific inquiry
threadlike bodies. Nematodes attack turfgrass roots.
Life Science:
pathogen: a disease-causing organism.
Interdependence of
symptoms: the external reaction of the plant to the organisms
disease: Different diseases cause different symptoms. Matter, energy, and
organization in living
Performance Objectives systems
The student will Behavior of
organisms
• identify five major turfgrass diseases: dollar spot, brown History and Nature of
patch, pythium blight, snow molds, and spring dead spot. Science:
Science as human
• describe the main disease control methods. endeavor
• explain how to prevent turfgrass disease by cultural Nature of scientific
knowledge
management.
Mathematical Skills
• describe the concept of pathological nematodes and their
control.
• list the most serious diseases on golf courses.
Materials Needed
For the class
• disease photos included in this lesson
• camera
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Unit V Golf Course management Lesson 9
For each small group of students
A disease identification form
For each student
Student sheet
Figure 1. The Disease Triangle
Turfgrass Host
Pathogen Environment
Favorable conditions for the development of most turf
diseases
• Wet and warm conditions
• Excessive water and nitrogen
• Weak turfgrasses
The main cause for turf disease is fungus
pathogens
Background Information
There are about two dozen common turfgrass diseases and most of them are
fungus diseases. Some diseases such as brown patch, pythium blight, and gray
leaf spot require preventive programs. The disease triangle is used to describe
the disease development and includes the host (turfgrasses), the causal agent
(pathogens), and the environment (favorable to the pathogen)
Some turfgrass diseases are specific to the hosts. For example, gray leaf spot
seriously attacks perennial grass and St. Augustinegrass; strip smuts attack
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Unit V Golf Course management Lesson 9
Kentucky bluegrass; spring dead spot attacks bermudagrass. Poorly maintained
turfgrasses are more susceptible to pathogens.
High nitrogen fertilization will enhance diseases such as brown patch, pythium
blight, leaf spots, and spring dead spots. However, low nitrogen fertilization also
contributes to the disease susceptibility of dollar spot, red thread, and rusts.
High humidity and warm temperatures will help the development of most of the
fungal pathogens. Reducing the turf surface moisture such as dew removal is a
common practice used to reduce disease potential.
Fungi reproduce themselves by producing either asexual or sexual spores. The
vegetative body of a fungus is called mycelium and the parts of the mycelium
are called hyphae. A fungus infection can develop within hours and the
symptoms developed help with disease identification. Disease identification is
the first step to control a turf disease.
Fungicides are used to control turf diseases. Systemic and contact fungicides
are the two common types of fungicides used for lawn disease control.
Systemic fungicides provide a longer period of control and are effective to
control pathogens in soils. Contact fungicides provide a foliar protection.
Table 1. Comparison of Diseases on Bermudagrass and Creeping
Bentgrass Greens
Seasonal Creeping Bermudagrass Control
Diseases Bentgrass Green Green methods
Spring Dollar spots, Snow Spring dead spot, Culture
molds, yellow brown patch enhancement
patch of turf,
fungicide
application
Summer Brown patch, Preventive
pythium blight, management
dollar spot,
Anthracnose, take
all patch,
Fall Dollar spot Spring dead spot Reduce
(not visible yet), nitrogen
damp off (winter application.
over-seeding turf) Preventive
fungicide
application
for spring
dead spot
Winter Snow molds, Preventive
yellow patch fungicide
application
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Unit V Golf Course management Lesson 9
Nematodes are small animals found in soils. They are non-segmented worms
ranging in length from 1/100 to 1/25 of an inch. They attack the root systems
of lawns by feeding on root cells and they also secrete substances that often
cause abnormal enlargement of root cells. Nematodes usually do not kill the
turf but can seriously weaken the lawn. Nematodes more often cause problems
in the southern states than in the North. A soil sample should be taken and
sent to a diagnostic laboratory when a nematode problem is suspected. A
chemical treatment should be applied only after a diagnostic laboratory's
recommendation.
The main difference between the diseases found on lawns and golf courses is
due to lower mowing height. The diseases happening on greens, tees or
fairways will spread much faster and become more serious than a turf with a
higher cut. The heavy traffic and frequent mowing on golf courses will further
speed the spread of diseases. The most common diseases on golf courses is
dollar spot. The most serious diseases on golf courses are pythium blight,
brown patch, and gray leaf spot, which can kill a whole turf area within a
couple of days. However, any disease, without proper protection and treatment
can be devastating.
A combination of cultural management and an effective fungicide program is
needed for most golf courses. Cultural control methods include selecting
disease resistant turfgrasses, reducing nitrogen and water use during humid
and moist conditions, and growing a healthy turf in general. A healthy turf will
have greater resistant to pests than a weak turf. When a fungicide is necessary,
proper identification of the disease is essential. Integrated Pest Management
(IPM) is a part of the pest management strategies for golf courses and other turf
areas. IPM is a strategy using sound combination of all possible pest
management programs with minimum input to prevent and cure the pest
problem (Refer the IPM lesson page).
Teacher Preparation
• Collect a fungicide label
• Prepare disease posters of dollar spot, brown patch, pythium blight, gray leaf
spot, and spring dead spot based on the background information. The poster
should include the followings:
Ø Disease photo
Ø Host species
Ø Favorable conditions
Ø Typical symptoms
Ø Main control methods
• Duplicate student sheet
Procedure
1. Introduce the students to the major turf diseases found on golf courses.
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Unit V Golf Course management Lesson 9
2. Divide students into small groups to study a particular disease and ask each
group to report on that disease. The report of the disease should include:
Ø Host of the disease
Ø Most favorable conditions for the disease
Ø Most unique symptoms of the disease
Ø General control methods of the disease
3. Exchange the posters and study different diseases.
4. Explain nematodes and how they damage turfgrasses.
5. Discuss cultural controls including the use of resistant turfgrass, avoiding
evening irrigation, and keeping turfgrass healthy.
6. Present the fungicide label.
7. Ask student to complete the student sheet.
Reflection
Why are diseases very serious on very short turf?
Name the most serious diseases found on golf courses. What are the most
favorable conditions for these diseases?
Who is responsible for identifying diseases? How are diseases identified?
Enhancement
• Visit more turf related web sites with turf disease information (see the reference
list and the CD ROM).
• Visit more lawns and collect photos of diseased turf.
• Interview a lawn technician about disease control.
Assessment
Determine the students' performance based on
• the degree of accomplishment on the student sheet.
• the performance during the class or the experiment.
• the participation in the discussion and the reflection questions.
• the degree of accomplishment on the "Scoring Rubric".
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Unit V Golf Course management Lesson 9
STUDENT FACT SHEET Student ________________ Date____________
TURF DISEASES AND CONTROLS ON GOLF COURSES
1. Most turf diseases are caused by fungi.
2. Fungal pathogens reproduce by producing spores.
3. The body of a fungus is composed of numerous threadlike filaments
called mycelium.
4. Turf disease problems are most common during periods of high humidity
and warm temperatures.
5. Cultural management is an effective way to prevent turf diseases.
6. The first step in disease prevention is to select resistant species or
cultivars.
7. Fungicides are often used to control turf diseases.
8. The IPM program is used on golf courses for effective pest control.
9. The most common disease found on the golf course is dollar spot
10. The most devastating diseases are pythium blight, brown patch, and gray
leaf spot.
11. A pest license is required to apply ant pesticide on golf courses
12. A fungicide has three names: common name, trade name, and chemical
name.
13. A fungicide must be registered by EPA before it can be used.
14. The label of a fungicide is a legal document.
15. Fungicides are pesticides and are toxic.
16. Proper handling and storage of fungicides are required by law.
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Unit V Golf Course management Lesson 9
STUDENT SHEET Student ________________ Date____________
TURF DISEASES AND CONTROLS ON GOLF COURSES
1. Write the definition:
disease:
fungicides:
fungus:
hyphae:
infection:
mycelium:
nematodes:
pathogen:
symptoms:
2. Compare the turf disease potential of lawns and golf courses.
3. What are the main things listed on the fungicide label
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Unit V Golf Course management Lesson 9
4. List the disease conditions by filling in the table
Disease Hosts Favorable Fungicide Cultural
conditions to control control
the disease method methods
Dollar spot
Brown Patch
Pythium
blight
Snow molds
Spring dead
spot
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Unit V Golf Course management Lesson 9
A SCORING RUBRIC Name ________________Date _____________
TURF DISEASES AND CONTROLS ON GOLF COURSES
The purpose of this
lesson was
The main method(s)
or procedure(s) we
learned was (were)
The best example(s)
that I can use to
describe the content
of this lesson
Subjects or courses
that I can relate this
lesson to
The information of
this lesson can be
applied to
In summary, what I
learned
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Unit V Golf Course management Lesson 9
Fungicides
Fungicides are types of pesticides, which are used to stop or prevent fungal
diseases. Fungicides normally do not kill the pathogenic fungus, but rather
stop it from further spreading. For some fast spreading diseases such as
pythium blight, brown patch, and gray leaf spot, a preventive fungicide
program is necessary.
A fungicide as well as any other pesticide, must be registered through the
Environmental Protection Agency (EPA), and have a registration number
before it can be purchased. A fungicide should have three names: common
name, trade name, and chemical name and a label, which provides legal
information for the content of the fungicide, the instructions for use, and a
warning sign of the level of toxicity. Any violation on a pesticide label is illegal
since a pesticide label is a lawful document.
The fungicides applied to turf areas can be divided into two groups based on
the means by which they control diseases. A contact fungicide protects foliar
turf areas by providing an external protection from the pathogen. A systemic
fungicide is absorbed by the turfgrass and translocated throughout the plant
body to internally protect the plant in addition to the external protection. Since
mowing will not remove the internally absorbed fungicide, a systemic
fungicide will last longer to protect the turf area than a contact fungicide.
Certain types of fungicides can be mixed together to enhance the protection
for a single disease or multiple diseases. An improper mix may reduce the
fungicide efficiency. Alternating different fungicides for a single diseases is
highly recommended since pathogens may develop fungicide resistance after
repeated use of the same fungicide.
Fungicide must be applied after mowing on a calm day. The most common
time of the day is early morning after mowing. The operator must have a
pesticide license and proper protection. Fungicides are toxic and great
caution must be taken when applying.
Proper handling and storage of fungicide is also required by law. Avoiding
any unnecessary application of pesticides and protecting the environment is
the basic work ethic a green industry worker should have.
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Unit V Golf Course management Lesson 9
COMMON TURF DISEASES
Dollar Spot
Fungus disease
Small foliar patch disease. All
turfgrasses are susceptible to
dollar spot.
Control by using adequate
nitrogen fertilization and
fungicides.
Brown Patch
Fungus disease
A patch disease affecting
turfgrasses when it is hot and
humid
Control by using adequate
fungicides and reducing
fertilization in spring season.
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Unit V Golf Course management Lesson 9
Fairy Rings
Fungus disease
Circular abnormal
appearance. All turfgrasses
are susceptible to the disease
Control by cleaning the soil and
light nitrogen applications.
Gray Snow Mold
Fungus disease
A patch disease affecting
turfgrasses when it is cold
with snow cover
Control by using adequate
fungicides and reducing
fertilization in fall season.
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Unit V Golf Course management Lesson 9
Leaf Spots
Fungus diseases
Several different types of foliar
diseases affecting all
turfgrasses.
Control by using adequate
fungicides.
Pink Snow Mold
Fungus disease
A patch disease affecting
turfgrasses when it is cold
with or without snow cover
Control by using adequate
fungicides and reducing
fertilization in fall season.
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Unit V Golf Course management Lesson 9
Powdery Mildew
Fungus disease
White powdery cover on
turfgrass leaves and shoots.
Wet and shade conditions are
favorable for the disease.
Control by using adequate
turfgrass and fungicides
Pythium Blight
Fungus disease
Fast spreading patch disease
of cool-season turfgrasses
and bermudagrass. The
disease happens during a hot
and humid summer
Control by using adequate
preventive fungicides.
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Unit V Golf Course management Lesson 9
Red Thread
Fungus disease
Red thread appearance affects
slow-growing turfgrasses with
poor soil fertility conditions.
Control by using adequate
fertilization and fungicides.
Rusts
Fungus diseases
Affect slow-growing
turfgrasses with poor soil
fertility conditions.
Control by using adequate
fertilization and fungicides.
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Unit V Golf Course management Lesson 9
Smuts
Fungus diseases
Foliar cool-season turfgrass
diseases .
Control by using adequate
fungicides and reducing nitrogen
fertilization.
Summer Patch
Fungus disease
A summer patch disease
affecting Kentucky bluegrass.
Control by using adequate
fungicides and reducing
fertilization in spring season.
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Unit V Golf Course management Lesson 9
Take-all Patch
Fungus disease
A patch disease affecting
turfgrasses when soil pH is
high
Control by using adequate
fungicides and reducing
fertilization in spring season.
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