• TABLE OF CONTENTS
HIDE
 Introduction
 Avoidance
 Cultural control
 Host resistance
 Thresholds
 Chemical control
 Pesticide performance
 Attention
 Tables






Title: Professional disease management guide for ornamental plants
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
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Permanent Link: http://ufdc.ufl.edu/UF00066809/00001
 Material Information
Title: Professional disease management guide for ornamental plants
Series Title: Plant Pathology Fact Sheet PP202
Physical Description: Book
Language: English
Creator: Bledsoe, S. D.
Harmon, P. F.
McGovern, R. J.
Affiliation: University of Florida -- Florida Cooperative Extension Service -- Department of Plant Pathology -- Institute of Food and Agricultural Sciences
Publisher: University of Florida Cooperative Extension Service, Plant Pathology Department, Institute of Food and Agricultural Sciences
Publication Date: 2004
 Subjects
Spatial Coverage: North America -- United States of America -- Florida
 Record Information
Bibliographic ID: UF00066809
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
    Introduction
        Page 1
    Avoidance
        Page 2
    Cultural control
        Page 3
    Host resistance
        Page 4
    Thresholds
        Page 5
    Chemical control
        Page 6
    Pesticide performance
        Page 7
    Attention
        Page 8
    Tables
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
Full Text





UNIVERSITY OF

FLORIDA


IFAS EXTENSION


Professional Disease Management Guide for Ornamental

Plants1


S. D. Bledsoe, P. F. Harmon, and R. J. McGovern2

The ornamental plant industry thrives in Florida
because of the warm, humid environment that makes
Florida a gardeners paradise and a compatible
location to mass produce numerous species of plants.
These ideal conditions are also suitable for the
development of a wide variety of plant pests
including pathogenic bacteria, fungi, and viruses.
Mild winters in Florida also facilitate survival of
some insects that can spread plant pathogens,
especially viruses. Growers are challenged to
develop the most efficient production plan possible
incorporating as many tactics as possible to maximize
plant health and minimize opportunities for pest and
disease outbreaks a concept known as integrated
pest management (IPM). This publication is intended
to be used by growers, landscape professionals, and
other pest control operators as a reference for
managing diseases of ornamental plants.
Management tactics are outlined under the following
key components of an IPM program: prevention,
cultural control, scouting, physical control, biological
control, and chemical control. Tables 1 4 contain
important information on commercial products
currently available for the management of diseases in
ornamental plants. In addition, a list of useful


websites and references is provided at the end of this
document to supplement the information provided
herein.

Disease Prevention

Once symptoms of a disease or pest problem are
evident, management can be difficult, costly, or
maybe impossible. Some basic management practices
can help prevent pest problems from occurring in the
first place. The following precautions can reduce the
likelihood of plant disease development and spread:

Exclusion

Exclusion implies that healthy plants or
pathogen-free planting media are kept in an isolated
area that excludes plant pathogens. Plants are often
grown in a nursery or greenhouse where care is taken
to ensure that planting stock and media are disease
and pathogen free. When ordering seeds, bulbs, or
tubers, find out if they are certified to be
pathogen-free. If possible purchase planting media
that has been pasteurized to kill plant pathogens and
pests. All media should be stored in original bags
until use, or in covered containers to prevent
contamination by plant pathogens. Some procedures


1. This document is PP202, one of a series of the Plant Pathology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida. Original publication date April 2004. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.
2. S.D. Bledsoe Doctor of Plant Medicine graduate, P.F. Harmon, assistant professor, R.J. McGovern, professor, Plant Pathology Department, Cooperative
Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.


PP202


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity Affirmative Action Employer authorized to provide
research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion,
age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For information on obtaining other extension
publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service / Institute of Food and Agricultural
Sciences / University of Florida / Larry R. Arrington, Interim Dean







Professional Disease Management Guide for Ornamental Plants 2


for reducing pathogen populations in native soil and
planting stock are listed below (see "physical
control"). If new plants are brought into a
production system from an outside source, it is wise
to isolate them from other plantings for a period of
time to make sure they are free of pathogens and
other pests.

Avoidance

Precautions taken that enable plants to escape
pathogens that are present in the growing
environment are known as avoidance measures.

Avoidplant damage Take care not to damage
plants during installation and maintenance of the
landscape. Damaged roots and other plant parts
provide sites of entry for disease-causing organisms.
Rough handling of root balls can cause broken roots
and interfere with the plants ability to take up water
and nutrients. Make sure the plants are secured
during transport and placed gently (not dropped) into
planting holes. Once established, avoid damage to
trees and shrubs from line trimmers. Such damage
interferes with the vascular system of the plant in
addition to creating an infection court.

Over-pruning weakens trees and shrubs, making
them more susceptible to attack by pathogens and
pests. No more than 30% of the foliage should be
removed at one time. Unless absolutely necessary, do
not remove branches that are more than about half the
diameter of the trunk. Large wounds take longer to
heal and are more likely to decay than small wounds.
Using tree wound paint on tree pruning wounds may
provide protection against insect pests. The
microenvironment beneath bubbling or deteriorating
paint can provide an ideal niche for damaging
microorganisms.

Using "immature" planting mixes that contain
incompletely composted bark or fresh manure may
result in damage to plants from the release of heat
and toxic compounds. Manure should be completely
dry and loose before adding to planting mix. Be sure
to thoroughly combine all constituents into a uniform
blend. If in doubt, pre-mixed potting soils purchased
wholesale, at nurseries, or in garden centers provide
an alternative to mixing your own.


Insects and nematodes cause feeding damage
that provides ideal sites of entry for many pathogenic
fungi and bacteria. Some may also spread viruses, for
example western flower thrips and five other thrips
species can transmit tomato spotted wilt virus to
many plants including chrysanthemum, gloxinia, and
impatiens. The stubby root nematode can transmit
tobacco rattle virus to several ornamental plants
including gladiolus, iris, tulip, and orchid.
Maintaining these organisms below damaging levels
will reduce feeding damage, help maintain plant
health, and may also reduce the incidence of certain
insect- and nematode-vectored plant pathogens.

Manipulate time of planting Manipulating the
growing period to a time when climatic conditions do
not favor disease development can help avoid losses.
This may be a good option for plants with seasonal
versatility and no resistant varieties. Pentas are very
susceptible to Phytophthora root rot and blight during
warm and wet weather. Planting pentas either before
or after the rainy season is a good way to avoid losses.

Sanitation

Sanitation practices are "cleanliness"
measures that can reduce unintentional spread of
plant pathogens from diseased to healthy plants
directly through mechanical transmission or
indirectly from pathogen reservoirs.

Avoid mechanical transmission ofpathogens -
Hands and pruning tools can be readily contaminated
when working with diseased plants, especially if the
causal agent is bacterial, viral, or present in the
vascular system (i.e. vascular wilts). Fusarium wilt
of queen palms is a devastating disease which can be
transmitted through pruning, thus readily spread to
other queen palms in a nursery or landscape.
Routinely sanitize all items which come into contact
with plants, soil, or debris. A 10- to 20-percent
solution of household bleach in water makes a good
disinfectant for tools and soles of shoes but is quite
corrosive. Examples of commercial disinfectants
marketed toward plant production personnel include
Consan Triple Action 20, Green Shield, and Physan
20. Dispensers for hands, tools, and foot baths should
be set up at production house entrances. Hand
sanitizers typically contain alcohol and should also be
provided in hand dispensers. Washing followed by


Professional Disease Management Guide for Ornamental Plants


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Professional Disease Management Guide for Ornamental Plants 3


steam sterilization is an excellent method of reducing
pathogen populations on trays, pots, and other
production tools. Read and follow the temperature
recommendations in manufacturers guidelines to
avoid heat damage. The use of plastic transplant tray
liners may also reduce the spread of disease.
Concrete walkways in production houses are helpful
because they can be regularly cleaned and disinfested
with ease.

Eliminate pathogen reservoirs Always move
diseased plants away from healthy plants and either
destroy them or treat them in an isolated area. Plant
debris and cull piles are excellent reservoirs for plant
pathogens and should be kept away from and
downwind of healthy plants and production areas.
Personnel should disinfest hands, shoes, and tools
after handling rogued, diseased, or decaying plant
material before resuming regular duties.

Weeds often harbor pathogens and insects that
spread them. Keep weeds suppressed in landscapes,
plant production systems, and, as feasible, in
surrounding areas. Weed control also reduces
competition for water and nutrients, and increases air
circulation. The use of mulch can help control weeds,
improve soil structure, and increase water retention in
the soil.

Occasionally plant pathogens are inoculated onto
healthy plants through irrigation systems. This
commonly occurs when irrigating with surface water
from ditches or holding ponds or when irrigating with
an ebb-and-flow system. Treatment with ultraviolet
light or a chemical sanitizer can reduce pathogens in
contaminated irrigation water.

Cultural Control

Cultural control means employing good
horticultural practices to optimize plant health and
decrease plant stress which in turn decreases the
likelihood of disease development.

Proper Cultivation

The first line of defense in the management of
plant pest problems is to provide the required
conditions for optimal plant growth and development.
Plants are often transplanted in certain locations


within landscapes solely for aesthetic purposes. The
soil type, soil porosity, sunlight exposure, soil pH,
and microclimate of the location should all be
considered before a plant species is chosen to avoid
conditions that are not conducive for healthy growth.
Planting in improper locations can increase plant
stress and the likelihood of pest problems. This may
lead to more frequent pesticide applications, which
may be ineffective and increase labor costs.
Transplants are particularly vulnerable to plant
pathogens during the first few weeks after planting
and may require special care to prevent disease
outbreaks.

Fertilization and Irrigation

Adequate fertilization is needed to avoid nutrient
deficiencies and keep plants healthy enough to resist
and recuperate from diseases. Too much nitrogen,
however, can encourage excessive growth of new
shoots, which may be more susceptible to plant
pathogens than "hardened" more mature growth.
One method in the control of Fireblight, a bacterial
disease of some ornamental fruit trees, is to decrease
nitrogen fertilization and irrigation to inhibit the
formation of new shoots where the pathogen may
attack. In extreme cases, over-fertilization can also
cause an excess of soluble salts in the soil. When this
happens, scorching of the leaves or "salt bur" may
occur because damaged plant roots cannot take up
enough water. Do not assume that more is better
regarding the application of fertilizers and chemicals
to plants; always follow label rates!

Soils with poor drainage will become
water-logged due to over-irrigation. The lack of
oxygen in these conditions causes many root cells to
collapse, diminishing plant uptake of water and
nutrients. Other cells may become non-selective,
allowing toxic metals and substances to be taken up
by the plant. Many of these plant poisons such as
nitrites are produced by microorganisms that thrive in
wet (anaerobic) conditions. Further damage occurs
from organisms known as facultative parasites that
are attracted to decaying tissue. Most ornamental
plants, especially succulent annuals, lack vigor, will
wilt, and have leaves that are pale green or yellowish
in water-logged conditions. Some plants have
mechanisms or specialized structures adapted to


Professional Disease Management Guide for Ornamental Plants


3







Professional Disease Management Guide for Ornamental Plants 4


survival in wet soils. See "Landscape Plants for
Wet Sites" under useful websites and references to
choose appropriate plants for wet conditions.

Prolonged leaf wetness should be avoided to
minimize foliar diseases. Adequate plant spacing
promotes better air circulation, thereby decreasing
periods of leaf wetness. Early morning irrigation,
sub-irrigation, or the use of a drip system is also
recommended. Water quality varies depending on the
source and should be tested to be sure pH and soluble
salts are at acceptable levels for healthy plant growth.

Host Resistance

Cultivars of ornamental plants generally are not
selected based on their resistance to plant pathogens.
However, differences in relative susceptibilities of
cultivars to some pathogens exist and should be
considered when and where appropriate. Antique
roses, for example, are generally more tolerant of
black spot and other diseases that infect roses than
most of the more recently-developed rose hybrids.
"Natchez" is a cultivar of crape myrtle that is
commonly used in Florida because of its resistance to
powdery mildew.

Systemically acquired resistance (SAR) has
shown promise in reducing disease in a number of
crops. This phenomenon is a reaction in a plant that
is triggered by various substances including salicylic
acid, chitosan, and monopotassium phosphate.
Applications of certain microorganisms including the
plant-growth promoting rhizobacteria Pseudomonas
and non-pathogenic isolates ofFusarium oxysporum
have also induced SAR. The bacterial protein, harpin
is commercially produced and sold under the trade
name Messenger and may offer some protection
against plant pathogens in food commodities, trees,
ornamentals, and turfgrasses. For more information
on harpin, see useful references and websites.

Crop Rotation

Many plant pathogens only cause disease on a
narrow range of closely related hosts. Continuous
cultivation of the same types of plants in an area for
long periods of time can result in elevated
populations of pathogens and other pests in the soil.
Periodic rotation of plants that are susceptible to


different pathogens may decrease populations of
harmful organisms and reduce the incidence of these
problems. Pest outbreaks tend to spread quickly
within monoculture systems. When appropriate, use
plants of many different families, species, or at least
cultivars within an area. Plant diversity will decrease
damage from pathogens and pests that attack specific
kinds of plants.

Scouting

Monitoring for plant problems on a routine basis
is the cornerstone of any IPM program and is
essential in detecting early pest infestations to prevent
economic loss. It is important to correctly ascertain
the causes) of plant problems so that appropriate
measures can be taken to correct them. This can be
tricky because sometimes plants respond in similar
ways to different types of stresses. Before disease
management steps are taken, other possibilities such
as insect or mite damage, nutrient or water
imbalances, pesticide damage, etc. should be ruled
out. If you don't know the recent history of the plant,
ask questions and observe the surroundings to obtain
clues that could lead you to a correct diagnosis.

Signs and Symptoms

Symptoms of plant diseases are often similar to
damage caused by abiotic stresses. The ability to
distinguish between the two is important. One should
also be able to recognize characteristics of healthy
plants such as normal speckling, spotting or
variegation that may be confused with disease
symptoms.

Signs refer to some part of a pathogen and are
visible during certain environmental conditions.
Signs are typically more difficult to find, but include
felty or moldy fungal sporulation, cob-web-like
fungal growth (mycelia), fruiting bodies [i.e.
mushrooms (large), pycnidia (tiny)], sclerotia, and
bacterial ooze. There are several references with
color pictures illustrating common diseases of
ornamental plants (see useful references and
websites) that may be helpful. If in doubt, contact
your local extension agent, university specialist, or a
professional consultant for advice. A digital image of
a plant disease sample can be submitted to university
specialists free of charge by using the Distance


Professional Disease Management Guide for Ornamental Plants


4







Professional Disease Management Guide for Ornamental Plants 5


Diagnostic and Identification System (DDIS)
through UF IFAS extension (http://ddis.ifas.ufl.edu/).
Some disease problems can be identified from a
picture, but most will need to be sent to a UF IFAS or
commercial diagnostic clinic for correct diagnosis.
This fee-based service will ensure an accurate
diagnosis and provide valuable documentation of the
problem. Ask if digital diagnosis is available from
your county extension office.

Thresholds

The presence of a pest or disease may not always
require treatment. Over time a level of damage
considered economically or aesthetically
unacceptable (i.e. economic threshold) should be set,
as well as a damage level at which action must be
taken to prevent reaching this point (i.e. action
threshold). In most cases, there are no set
recommendations for thresholds because various
systems differ widely in conditions that affect disease
pressure and in tolerances of plant damage. In
general, the threshold for damage to ornamental
plants is very low or zero because of inherent
aesthetic considerations.

Record-keeping

It is wise to document all management practices
as well as pest and disease outbreaks including
conditions under which they occur, control measures
taken (rates, number of applications, effectiveness,
etc.), and any other information that may be useful in
predicting and managing problems in the future.
Keep log sheets in chemical/fertilizer sheds and
require employees to document pertinent information
such as his/her name, date, chemical name, rate,
amount, sprayer used, and site each time an
application is made. Besides being required by laws
regulating pesticide usage, good records can aid in
problem-solving and may provide legal support in
cases of false allegations.

Physical Control

Physical control of disease-causing organisms is
obtained through mechanical procedures applied
directly to plants or substrates that reduce or eradicate
pathogen populations.


Steam Sterilization

Steam has been used to disinfest soil for over 100
years, and is practical for the sterilization of soil to be
used for potting and transplanting and for intensive
in-soil production of high value crops. An
application of aerated steam to maintain a uniform
soil temperature of 60-70C (140-1580F) for 30
minutes is sufficient to eliminate most
disease-causing organisms present in the soil. Be
sure the soil is free of clods, large pieces of plant
debris, and excessive moisture which if present will
hamper the penetration of the steam.

Soil Solarization

Soil solarization is an option for managing
soilbore pests in production systems and sunny
landscape settings during periods with little cloud
cover and rain. This technique utilizes clear plastic to
trap the radiant energy of the sun, which heats the soil
to temperatures sufficient to destroy many plant
pathogens and other pests without completely
eliminating beneficial organisms. Soil solarization is
often used when producing high-quality bedding
plants such as cut flowers.

Hot Water Treatment

Seeds, bulbs, tubers, and cuttings can be
immersed in hot water to kill potential pests including
pathogens. Daffodil and Easter lily bulbs are
commonly treated with hot water to kill any
nematodes that may be present. It is essential to
realize that accurate time and temperature controls
must be in place for the hot water treatment to be
successful. The temperature for pathogen inactivation
must not exceed the critical damage threshold for the
propagative material being disinfested.

Biological Control

The use of beneficial microorganisms to
suppress soil-borne and foliar plant pathogens is
known as biological control. Products containing
bacteria such as Bacillus, Pseudomonas, and
Streptomyces and fungi such as Gliocladium and
Trichoderma have reduced a variety of fungal plant
pathogens in various experiments, especially when
incorporated into transplant media or used as seed


Professional Disease Management Guide for Ornamental Plants


5







Professional Disease Management Guide for Ornamental Plants 6


treatments. Products containing biological control
agents that are currently available for disease
management of ornamentals are listed in Table 3,
along with the active organism(s) and disease
applications. Ongoing research at universities and
federal facilities continues to evaluate and develop
new biocontrols as well as expand the labeling of
existing products. The use of organic soil
amendments (e.g. compost, sewage sludge, etc.) may
enhance populations of beneficial microorganisms
already present in the soil. Biological control
technologies are environmentally friendly IPM tools
with great potential, but currently biological controls
do not adequately control ornamental plant diseases
on their own in most cases.

Chemical Control

Regardless of which other IPM strategies are
used, it is sometimes necessary to apply chemical
pesticides (i.e. fungicides, bactericides, etc.) to
manage plant diseases. Pesticide application should
be based on scouting reports and the presence of
environmental conditions conducive to disease
development in established planting systems. Avoid
using routine "calendar sprays" which can be
wasteful and destroy populations of beneficial
organisms.

Pesticides may be applied to ornamental plants in
a granular form, a liquid foliar spray, or a drench.
Most chemicals used in disease management are
applied as sprays or dusts aimed at fungal pathogens
on leaves and other aboveground plant parts.
Pesticides may be applied before planting to soil and
planting stock in a drench or dip, respectively.
Gaseous soil fumigants are sometimes applied as a
preplant treatment in mass plant production systems
and kill most organisms in the soil including fungi,
bacteria, nematodes, and weed seed. Fumigants are
highly toxic, therefore extreme safety precautions
must be taken to protect workers.

Choosing a Pesticide

Correct identification of a target disease and
pathogen is essential to choosing an appropriate
pesticide for its control (see "scouting"). Some
products kill only certain pathogens, while others are
effective against a broad range of organisms. A


chemical can be chosen from Table 1 based on the
disease group, which describes one or more of the
following: the type of symptom exhibited by the
plant (e.g. blight, scab, rot), part of plant affected
(e.g. flower, leaf, root, etc.), type of pathogen
causing the disease (e.g. downy mildew, powdery
mildew, etc.), or the specific pathogen causing the
disease (e.g. Phytophthora, Stromatinia, etc.).
Disease groups describing general symptoms (i.e. leaf
spots, blights, scabs) may be caused by many
different pathogens. It is not likely that every
chemical listed for such disease groups will control
every possible pathogen for that disease group.
Chemicals labeled for each disease group are listed by
common name. The common name is the active
ingredient contained within a product, which is sold
under a trade name. For example, azoxystrobin
(common name) is the active ingredient in the
fungicide Heritage (trade name). The chemical class
represents either the chemical structure or mode of
action of the active ingredient to which each chemical
belongs. Rotation of chemicals in different classes is
important in slowing the development of resistant
pest populations.

Trade names available for each chemical in
Table 1 are listed in Table 2, along with the activity
of each. There is usually more than one product
available for each active ingredient and some
products contain more than one chemical. The
activity of a chemical refers to its mobility in the
plant, and should be considered when choosing a
product. Systemic fungicides (S) usually move
upward within a plant, though there are a few that
also move downward. They may be applied as foliar
sprays, seed treatments, root dips, soil drenches, or
tree injections. Locally systemic fungicides (LS)
have limited mobility in the direct vicinity of
application. Almost all systemic fungicides disrupt
only one or a few steps in fungal metabolism.
Therefore, resistance to these chemicals usually
occurs within a few years if used frequently. It is best
to use these products in combination or rotation with
broad-spectrum contact fungicides to delay
development of resistance. Advantages of using
systemic fungicides, however include longer residual
activity and survival of possible beneficial organisms
on the plant surface. Contact fungicides may have
protective or curative activity. Most fungicides and


Professional Disease Management Guide for Ornamental Plants


6







Professional Disease Management Guide for Ornamental Plants 7


bactericides are protectants (P) and must be present
on the surface of the plant in advance of the pathogen
in order to prevent infection. These chemicals may be
applied when environmental conditions are conducive
to a disease outbreak. Products with curative activity
(C) may be applied after the onset of disease. Some
chemicals have both protective and curative activity
that may depend on the rate of application.
Resistance to many contact pesticides is slow to
develop or non-existent because many different
metabolic pathl\ a% s of target organisms are
disrupted. Keep in mind that the overuse of these
products may also reduce populations of beneficial
organisms (i.e. biological controls).

Not all ornamental pesticides may be applied to
all ornamental plants depending on phytotoxicity and
location of the plant. Most pesticide labels have a list
of plants on which the product has been tested and
determined safe to treat, as well as plants not tolerant
of the product. It is a good idea to test unfamiliar
products on a few plants before applying it on a large
scale to prevent loss. Products in table 2 with bold
font are legal to use on plants not listed on the label if
tested and found to be safe in small scale trials.

Pesticide Performance

Insufficient coverage is one of the most common
reasons for pesticide failure. Calibrate sprayers on a
regular basis and maintain them in good working
order to get the best performance and coverage.
Many pesticides are broken-down hydrolyzedd) when
mixed with water above pH 7. Be aware of the water
pH and when above 7 use an appropriate buffering
solution in the tank to maintain pH in the 6.5 to 7
range. For safety and efficacy, pesticides should be
applied the same day they are mixed with water.



Phytotoxic effects characterized by marginal leaf
scorch, leaf spotting, or distortion of new growth may
occur if pesticides are applied too heavily, under
extremely hot or dry conditions ( water-stressed
plants), inappropriately mixed with a
spreader-sticker, or in an incompatible mixture (see
"tank mixtures"). Damage can be highly variable
depending on plant species and chemical applied.


Pesticide performance is sometimes altered by
the development of pathogen resistance, which may
develop if the same chemical, chemicals within the
same class, or with similar modes of action are
applied repeatedly over a long period of time. Once
resistance to a particular pesticide builds up within a
pest population, other products may also be rendered
ineffective (i.e. cross resistance). Modes of action for
each chemical class, along with resistance risk are
listed in Table 4. Chemical classes with multiple-site
modes of action generally pose the least risk for the
development of pathogen resistance. It is wise to use
rotations of chemicals within these classes, especially
when using ones of high resistance risk. Fungicide
labels often have specific recommendations on
resistance management which should be rigorously
followed.

Tank Mixtures

Spray tank mixtures of different pesticides (i.e.
fungicides, insecticides, miticides, etc.) and even
fertilizers may be chemically incompatible, resulting
in plant injury that does not occur if any one of the
products is used alone. When applying a new mix,
test on a few plants and wait 24-48 hours for signs of
phytotoxicity prior to large-scale use. Physical
incompatibility is also possible if combining products
does not result in a uniform mixture (i.e. clumping).
Products with similar formulations, classes, or made
by the same company may be more compatible,
however always refer to the labels and/or a
compatibility chart before tank mixing.

A spreader-sticker may be added to the spray
mixture to obtain better coverage and residual
persistence of a pesticide. Note that some ornamental
plants may be sensitive to spreader-stickers and other
additives. Check the label for restrictions. If in
doubt, test for safety on a few plants before
widespread use. Mixing by mechanical agitation in
the spray tank is often necessary to attain best
results.

Useful References

Chase, A. R., M. L. Daughtrey, and G. W.
Simone (eds.). 1995. Diseases ofAnnuals and
Perennials. G. J. Ball Pub. Co., Batavia, IL.


Professional Disease Management Guide for Ornamental Plants


7







Professional Disease Management Guide for Ornamental Plants 8


Chase, A. R. 1987. Compendium of Ornamental
Foliage Plant Diseases. A. R. Chase, APS Press,
St Paul MN.

Daughtrey, M. L., R. L. Wick, and J. L. Peterson
(eds.). 1995. Compendium ofFlowering Potted
Plant Diseases. APS Press, St. Paul, MN.

Daughtrey, M. and A. R. Chase. 1992. Ball Field
Guide to Diseases of Greenhouse Ornamentals.
G. J. Ball Pub. Co., Batavia, IL.

Elliott, M. L., T. K. Broschat, J. Y. Uchida, and
G. W. Simone (eds.). 2004. Compendium of
Ornamental Palm Diseases and Disorders. APS
Press, St. Paul, Minnesota.

Hansen, E. M., and K. J. Lewis. 1997.
Compendium of Conifer Diseases. APS Press, St.
Paul, MN.

Jones, R. K., and D. M. Benson. 2001. Diseases
of Woody Ornamentals and Trees in Nurseries.
APS Press, St. Paul, MN.

Short, D. E., G. W. Simone, and R. A. Dunn,
2001. Commercial Ornamental Nursery Scouting
Manual. University of Florida-IFAS Extension
Publication SP 235, Gainesville, FL.

Horst, R. K. 1983. Compendium of Rose
Diseases. APS Press, St. Paul, MN.

Horst, R. K, and P. E. Nelson (eds.). 1997.
Compendium ofC( l, y,,,iiin ,,, Diseases. APS
Press, St. Paul, MN.

Care of Ornamental Plants in the Landscape
(fertilization):
http://pubs.caes.uga.edu/caespubs/pubcd/
B 1065.htm

Distance Diagnostic Identification System -
http://edis.ifas.ufl.edu/TOPICDDIS

EDIS homepage http://edis.ifas.ufl.edu/

Florida Crop/Pest Management Profiles:
Ornamentals: http://edis.ifas.ufl.edu/PI038

Harpin fact sheet, EPA:
http://www.epa.gov/pesticides/biopesticides/
ingredients/factsheets/factsheet_006477.htm.


IPM Florida http://ipm.ifas.ufl.edu/

Key for Identifying Landscape Turfgrass Disease
http://edis.ifas.ufl.edu/LH064

Landscape Plants -
http://edis.ifas.ufl.edu/TOPIC_LandscapePlants

Landscape Plants for Wet Sites:
http://www.ces.ncsu.edu/depts/hort/hil/hil-
646.html

Ornamental Pest Management at Ft. Lauderdale
REC
http://www.ftld.ufl.edu/entomo/
OrnamentalPests/orapest.htm

Plant Information Databases -
http://hort.ifas.ufl.edu/database/databases.htm

(nutrient deficiencies, propagation, tree & shrub
fact sheets)

Planting trees in landscapes by Ed Gilman -
http://hort.ifas.ufl.edu/woody/planting/ (tree &
shrub planting, production, pruning, and more)

Selecting and Planting Trees and Shrubs:
http://edis.ifas.ufl.edu/MG077

Weed Management Guide:
http://edis.ifas.ufl.edu/
TOPICGUIDE_WeedManagementGuide

Woody Ornamentals -
http://hort.ifas.ufl.edu/woody/index.htm

Attention

Always read, understand, and follow all label
instructions including safety precautions, required
personal protective equipment (PPE), range of
target organisms, rates of application, risks of
phytotoxicity, and compatibility with other
chemicals before application.


Professional Disease Management Guide for Ornamental Plants


8








Professional Disease Management Guide for Ornamental Plants 9


Table 1. Chemicals used to manage diseases of ornamental plants. a


Disease ground Chemical common name Chemical class


Fungal foliar blights and
leaf spots


azoxystrobin


Qol (strobilurin)


captain phthalimide
chlorothalonil benzonitrile
chlorothalonil + fenarimol benzonitrile + DMI pyrimidinee)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile + inorganic
copper hydroxide inorganic
copper hydroxide + mancozeb inorganic + EBDC0
copper oxychloride inorganic
copper sulfate inorganic
copper sulphate pentahydrate inorganic
dicloran nitroaniline
dimethomorph + mancozeb cinnamic acid+ EBDC
fenhexamide hydroxyanilide
ferbam dithiocarbamate
fludioxonil phenylpyrrole
flutolanil carboxamide
iprodione dicarboximide
kresoxim-methyl Qol (strobilurin)
mancozeb EBDC
maneb EBDC
myclobutanil DMI (triazole)
neem oil extract lipid
PCNB substituted aromatic
potassium bicarbonate bicarbonate
propiconazole DMI (triazole)
sulfur inorganic
thiophanate methyl benzimidazole
triadimefon DMI (triazole)
trifloxystrobin Qol (strobilurin)
triflumizole DMI (imidazole)


vinclozolin


dicarboximide


Phytophthora blight azoxystrobin Qol (strobilurin)
chlorothalonil benzonitrile
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile
dimethomorph + mancozeb cinnamic acid+ dithiocarbamate
fosetyl-aluminum phosphonates
mancozeb EBDC
phosphorous acid phosphonates
Bacterial leaf spots, copper hydroxide inorganic
blights copper sulphate pentahydrate inorganic
copper hydroxide + mancozeb inorganic + EBDC
copper sulfate inorganic
fosetyl-aluminum phosphonates
_phosphorous acid phosphonates


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Professional Disease Management Guide for Ornamental Plants 10


Table 1. Chemicals used to manage diseases of ornamental plants.


Bacterial soft rot copper hydroxide inorganic
copper sulphate pentahydrate inorganic
streptomycin sulfate antibiotic
Downy mildew azoxystrobin Qol (strobilurin)
copper hydroxide inorganic
copper sulphate pentahydrate inorganic
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
dimethomorph + mancozeb cinnamic acid+ dithiocarbamate
fosetyl-aluminum phosphonates
kresoxim-methyl Qol (strobilurin)
mancozeb EBDC
maneb EBDC
neem oil extract lipid
phosphorous acid phosphonates
trifloxystrobin Qol (strobilurin)
Powdery mildew azoxystrobin Qol (strobilurin)
chlorothalonil benzonitrile
chlorothalonil + fenarimol benzonitrile + DMI pyrimidinee)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile
copper hydroxide inorganic
copper oxychloride inorganic
copper sulfate inorganic + sulfur
fenarimol DMI pyrimidinee)
kresoxim-methyl Qol (strobilurin)
myclobutanil DMI (triazole)
neem oil extract lipid
piperalin piperidines
potassium bicarbonate bicarbonate
potassium salts of fatty acids insecticidal soap
propiconazole DMI (triazole)
sulfur inorganic
thiophanate methyl benzimidazole
triadimefon DMI (triazole)
trifloxystrobin Qol (strobilurin)
triflumizole DMI (imidazole)


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Professional Disease Management Guide for Ornamental Plants 11


Table 1. Chemicals used to manage diseases of ornamental plants.


Petal, flower blights


Rusts


captain


dicarboximide


chlorothalonil benzonitrile
chlorothalonil + fenarimol benzonitrile + DMI pyrimidinee)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile
dimethomorph + mancozeb cinnamic acid+ EBDC
ferbam dithiocarbamate
iprodione dicarboximide
mancozeb EBDC
maneb EBDC
myclobutanil DMI (triazole)
neem oil extract lipid
PCNB substituted aromatic
propiconazole DMI (triazole)


triadimefon


II *


azoxvstrobin


DMI (triazole)


Qol (strobilurin)


chlorothalonil benzonitrile
chlorothalonil + fenarimol benzonitrile + DMI pyrimidinee)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile
copper hydroxide + mancozeb inorganic + EBDC
dimethomorph + mancozeb cinnamic acid+ EBDC
fenarimol DMI pyrimidinee)
ferbam dithiocarbamate
flutolanil carboxamide
kresoxim-methyl Qol (strobilurin)
mancozeb EBDC
maneb EBDC
mvclobutanil DMI (triazole)
neem oil extract lipid
oxycarboxin carboxamide
propiconazole DMI (triazole)
sulfur inorganic
thiophanate methyl benzimidazole
triadimefon DMI (triazole)
trifloxystrobin Qol (strobilurin)


trfuioeD1(raoe





Professional Disease Management Guide for Ornamental Plants


11


triflumizole


DMI (triazole)








Professional Disease Management Guide for Ornamental Plants 12


Table 1. Chemicals used to manage diseases of ornamental plants.


azoxystrobin


Qol (strobilurin)


chlorothalonil benzonitrile
chlorothalonil + fenarimol benzonitrile + DMI pyrimidinee)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
chlorothalonil + zinc benzonitrile
dimethomorph + mancozeb cinnamic acid+ EBDC
fenarimol DMI pyrimidinee)
kresoxim-methyl Qol (strobilurin)
mancozeb EBDC
myclobutanil DMI (triazole)
potassium bicarbonate bicarbonate
thiophanate methyl benzimidazole


triflumizole


DMI (triazole)


Cylindrocladium root rot chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
dimethomorph + mancozeb cinnamic acid+ dithiocarbamate
fludioxonil phenylpyrrole
iprodione dicarboximide
thiophanate methyl benzimidazole
triflumizole DMI (triazole)
Fusarium rot (root, bulb, azoxystrobin Qol (strobilurin)
etc.) & wilt chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
fludioxonil phenylpyrrole
iprodione dicarboximide
thiabendazole benzimidazole
thiophanate methyl benzimidazole
triflumizole DMI (triazole)
Gliocladium rot chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
thiophanate methyl benzimidazole
Myrothecium stem, chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
crown, root rot thiophanate methyl benzimidazole
trifloxystrobin Qol (strobilurin)
Pythium, Phytophthora captain dicarboximide
rot etridiazole thiadiazole
fosetyl-aluminum phosphonates
mefenoxam phenylamide
phosphorous acid phosphonates
propamocarb hydrochloride carbamate
Rhizoctonia rot azoxystrobin Qol (strobilurin)
chlorothalonil + thiophanate methyl benzonitrile + benzimidazole
fludioxonil phenylpyrrole
flutolanil carboxamide
iprodione dicarboximide
PCNB substituted aromatic
thiophanate methyl benzimidazole
triflumizole DMI (triazole)


Scabs





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Professional Disease Management Guide for Ornamental Plants 13


Table 1. Chemicals used to manage diseases of ornamental plants.


Table 2. Commercial products that contain one or more chemicals listed in Table 1.a


Chemical or combination Trade names Activity b
azoxystrobin Heritage S, P, C
captain Captan 50W P
chlorothalonil Chlorostar VI F, Concorde DF, Daconil, Manicure, P
Chlorothalonil DF, Echo 720
chlorothalonil + fenarimol Twosome Flowable Fungicide LS, P
chlorothalonil + thiophanate Spectro 90WG, Consyst WDG S, P, C
methyl
chlorothalonil + zinc Daconil Zn P
copper hydroxide Champion WP, Kocide 2000 TNO, etc. P
copper hydroxide + mancozeb Junction P
copper oxychloride COC DF, COC WP P
copper sulfate Basicop P
Copper sulphate pentahydrate Phyton 27 P
dicloran Botran 75W P
dimethomorph + mancozeb Stature WP LS, P, C
etridiazole Terrazole P
fenarimol Rubigan AS S, P, C
ferbam Ferbam Granuflo P
fludioxonil Medallion P
flutolanil Prostar 70 WP, Contrast 70 WSP S, P, C


Sclerotinia blight, stem PCNB substituted aromatic
rot
thiophanate methyl benzimidazole

vinclozolin dicarboximide
Sclerotium blight, stem azoxystrobin Qol (strobilurin)
rot fludioxonil phenylpyrrole
flutolanil carboxamide
-PCNB substituted aromatic
Stromatinia rot PCNB substituted aromatic
vinclozolin dicarboximide

Thielaviopsis root rot fludioxonil phenylpyrrole

thiophanate methyl benzimidazole

triflumizole DMI (triazole)

Algae b copper hydroxide + mancozeb inorganic + EBDC

a There may be several commercial products available for each chemical. Always check the label to be sure
the product is appropriate for particular plants and/or locations.
b Algae growth is typically an aesthetic problem and not a disease.
C Dithiocarbamates and relatives including ethylene bis-dithiocarbamate (EBDC).
d Check label for specific range of activity of each chemical listed within a disease group.


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Professional Disease Management Guide for Ornamental Plants 14


Table 2. Commercial products that contain one or more chemicals listed in Table 1.a


Table 3. Selected biological control products and reported disease applications a


Product Organism Disease applications
Actinovate Streptomyces lydicus soilborne diseases
AQ-10 Ampelomyces quisqualis powdery mildew control
Binab TF WP Trichoderma polysporum and T. controls a variety of fungal pathogens
harzianum
BlightBan A506 Pseudomonas fluorescens A506 Erwinia amylovora; fireblight
Companion, Kodiak Bacillus subtilis soilborne diseases (Rhizoctonia,
Phythium, Fusarium, Phytophthora,
Sclerotinia, Anthracnose, Botrytis)
Contans Coniothyrium minitans soilborne Sclerotinia spp.
Galltrol-A Agrobacterium radiobacter 1026 prevents crown gall


fosetyl-aluminum Aliette WDG S0, P
iprodione Chipco 26GT LS, P
kresoxim-methyl Cygnus S, P, C
mancozeb Dithane T/O, Fore Rainshield, Pentathlon DF, Protect P
T/O
maneb Pentathlon P
mefenoxam Subdue MAXX, Mefenoxam 2 S, P, C
myclobutanil Eagle 40WP, Systhane WSP S, P, C
neem oil extract Triact 70 P, C
oxycarboxin Plantvax 75W S, P, C
PCNB Blocker 4F, Revere 10G, Terraclor, Turfcide P
phosphorous acid Alude, Fosphite, Magellan S P
piperalin Pipron S, P, C
potassium bicarbonate Armicarb 100, Kaligreen P
insecticidal soap M-Pede P
propamocarb hydrochloride Banol S, P
propiconazole Banner Maxx, Propiconazole Pro S, P, C
streptomycin sulfate Agrimycin 17 P
sulfur Sulfur 6L, Sulfur 90W, Microthiol Disperss, etc. P
thiabendazole Mertect 340-F LS, P, C
thiophanate methyl Cavalier Flowable, Cleary's 3336, Fungo 50, etc. LS, P, C

triadimefon Bayleton 50, Strike 50 WDG S, P, C
trifloxystrobin Compass LS, P, C
triflumizole Terraguard 50W S, P, C
vinclozolin Touche EG LS, P, C
a Trade names are listed only for example. No endorsement or criticism of any product is intended by
its presence or absence from this table. Labels of products listed in bold font allow use on ornamental
plants not listed if tested and found to be safe by the applicator. Always read and follow pesticide label
instructions.
b Movement into the plant and type of control: S = upward systemic, LS = local systemic, P =
protective, C = curative
c Fosetyl-aluminum is the only fungicide in the table with upward and downward systemic movement.


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Professional Disease Management Guide for Ornamental Plants 15


Table 3. Selected biological control products and reported disease applications a


Mycostop Streptomyces sp. wilt and root rot caused by Pythium,
Fusarium, Botrytis, Alternaria, Phomopsis,
and to a lesser extent, Phythophthora and
Rhizoctonia.
PlantShield Trichoderma harzianum preventative control of foliar and root
fungal diseases
Rhapsody AS Bacillus subtilis QST 713 Strain Anthracnose (Colletotrichum spp.),
bacteria (Erwinia, Pseudomonas,
Xanthomonas)., black spot (Diplocarpon
rosae), Botrytis cinerea, fungal leaf spots,
and powdery mildew
RootShield Trichoderma harzianum strain T-22 Prevention of root rot caused by Pythium,
Rhizoctonia, and Fusarium.
SoilGard 12G Gliocladium virens GL-21 control of damping off and root rot
organisms
a See text for additional information


Table 4. Mode of action and resistance risk for each chemical class


Chemical Class Target Resistance Risk
benzimidazole Cell mitosis High
benzonitrile Multi-site Low
bicarbonate Unknown Unknown
carbamate Cell membrane Low to medium
carboxamide Fungal respiration Moderate
cinnamic acid Cell wall synthesis (proposed) Low to medium
dicarboximide Lipid peroxidation Moderate to high
Dithiocarbamate, EBDC Multi-site Low
DMI (demethylation inhibitor) Sterol biosynthesis Medium

hydroxyanilide Sterol biosynthesis Low to medium
inorganic Multi-site Low
lipid Unknown Unknown
nitroaniline Lipid peroxidation Low to medium
phenylamide RNA polymerase High
phenylpyrrole MAP protein kinase Low to medium
phosphonates Unknown Assumed low
phthalimide Multi-site Low
piperidines Sterol biosynthesis Low to medium
Qol (quinone outside inhibitor) or strobilurin Fungal respiration High
substituted aromatic Lipid peroxidation Low to medium
thiadiazole Lipid peroxidation Low to medium

a Information compiled from Fungicide Resistance Action Committee website: http://www.frac.info


Professional Disease Management Guide for Ornamental Plants


15




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