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Publication #PP-233

Homeowner's Guide to Fungicides for Lawn and Landscape Disease Management1

Philip Harmon, Aaron Palmateer, and Rachel Ribbeck2

Homeowners are generally discouraged from using fungicide products to manage diseases of the lawn and landscape for the following reasons:

  • Fungicide products only help manage some plant disease, not all.

  • Selection of appropriate products is dependent on knowing what disease is being managed, which is difficult to do based on visual appearance alone.

  • Timing applications is tricky. In many cases, the window of time when best performance is likely is narrow, and recognizing that window requires close observation of the plant and environment. In addition, for some diseases, once symptoms have developed, there is no available curative treatment, and fungicide applications will help only with preventing spread to other areas.

  • Measuring, diluting, and applying products effectively and safely require attention to detail, some specialized skills, and equipment.

That being said, many fungicides are packaged for and marketed to homeowners; when used appropriately, these can help manage some lawn and landscape diseases.

What is a disease?

Plants die for many reasons, not all of which are diseases. Many environmental stresses cause disorders that mimic diseases. For example, drought stress can kill a plant. Disease occurs when a pathogen infects a plant and disrupts growth or kills that plant over time. The most common plant pathogens include fungi, bacteria, and viruses.

Disease Triangle

Environmental factors influence disease development in the landscape. When the environment favors the host plant, disease is unlikely to occur. When environmental factors favor growth of the pathogen and infection of the host, disease is more likely to occur. All three sides of the disease triangle (Fig. 1) must be present for disease to occur: a susceptible host, a pathogen that can cause disease, and an environment favorable for infection and disease development.

Figure 1. 

Without all three sides, a triangle collapses. Disease only occurs when all three of the following are present: a pathogen that can infect a susceptible host plant during a time period with environmental conditions that favor infection and disease development.


[Click thumbnail to enlarge.]

Environmental factors affecting disease development include (but are not limited to) the following:

  1. Temperature – Fungal diseases occur over a wide range of temperatures.

  2. Moisture – High relative humidity favors fungal pathogen growth.

  3. Wind – Wind increases the spread of plant pathogens and the number of wounds on host plants.

  4. Wounds – Pruning and hedge trimming can create wounds that allow pathogens to enter a plant.

  5. Host – All plants are not susceptible to all pathogens; each pathogen has a host range.

  6. Soil Type – Sandy soil can stress plants because of its low moisture-holding capacity, while a high clay level can cause stress because of its excessive water-holding capacity.

  7. Fertility – Low fertility causes stress, while excessive fertilizers can provide a flush of growth that is more susceptible to disease.

  8. Light – Insufficient light can favor certain diseases.

  9. Herbicides – Herbicides can increase the severity of certain diseases.

  10. Air Pollutants – Air pollutants can cause direct symptoms on the host and affect the pathogen.

Disease Diagnosis

Because of the wide range of problems that occurs on the many plants in a landscape, determining which disease is affecting the plant or turfgrass is often difficult. Correctly diagnosing disease problems is critical because treatment recommendations are vastly different for different disease problems. To diagnose a plant disease problem, homeowners can

  • consult a lawn and landscape professional,

  • consult a Master Gardener or other knowledgeable plant person,

  • contact their county Extension agent for help, or

  • submit a sample to the UF IFAS Extension Plant Disease Clinic (http://edis.ifas.ufl.edu/SR007).

Once the cause of the problem is known, homeowners can determine how to manage it and prevent the problem from occurring again.

Disease Prevention

A proper irrigation schedule, good fertilization regime, and planting the right plant for the right place reduce the chance of some diseases becoming a problem. Maintaining healthy and stress-free plants helps reduce the chance that a landscape will become diseased. Just like humans, plants are more capable of thriving and surviving an infection if they are healthy and not already plagued by stress. When introducing new plants into the landscape, homeowners should take care to choose a strong and healthy plant that is not already infected with a pathogen. To do this, homeowners should look for signs (like fungus spores and structures) and symptoms (like wilts, spots, stunting, and cankers) of plant disease on the plant and root system. It is a good idea to only purchase plants from reputable and licensed nurseries. Inspect "bargain" plants carefully.

Even with the best cultural management regime, not all disease problems can be prevented. Fungicides can be very effective tools for disease management when the right product for the job is applied correctly and early enough in the development of the disease. Plant diseases can spread to other susceptible plants in a landscape. Fungicides are most effective when used to prevent disease spread to healthy plants.

Fungicide Facts

Fungicides are chemicals that inhibit the growth of fungi. There are many different chemical active ingredients that work as fungicides. Some active ingredients are sold in several different products and formulations. After a homeowner has diagnosed the disease problem and has received a fungicide management recommendation, it is important to carefully consider pesticide safety and selection.

Fungicides can be classified by how they work on the fungus and how they work on the plant. Products that work in a similar way on fungi have the same mode of action (also referred to as chemical family or class). Contact fungicides are sprayed onto plants and act as a protective barrier from pathogen infection. They prevent infections from occurring when applied before symptoms are visible, but infections that have already occurred will continue to develop. Systemic fungicides move into the plant, but movement inside the plant is limited. The vast majority of fungicides only move upward in the plant vasculature, but not down. Some fungicides only move locally into the plant part treated. Some systemic products exhibit curative action, which means the disease is stopped during its development. For a description of the types of systemic fungicides and additional information, see http://edis.ifas.ufl.edu/lh040.

All pesticides sold in the United States are required by law to have a label. The label contains a wealth of information about the product, including instructions for use, application, and storage; the plants to which the product can be legally applied; and the diseases against which the product may be effective. Any use of a pesticide that is not in accordance with its label is illegal.

Some fungicide products are labeled for bedding plants, shrubs, trees, and other ornamental plant uses in the landscape, but not turfgrass, and vice versa. As older active ingredients are re-examined by the EPA, uses that include residential turfgrass often are scrutinized and removed from product labels. Existing stock is usually allowed to be sold for a few years after label adjustment. During these transitions, both old and new products (with different sites on the labels) could be available in the marketplace. Situations like this are confusing and reinforce the need for users to carefully read and follow product labels each time they use a pesticide.

Fungicides available at local garden center retailers are available to the general public and are marketed toward the homeowner or private pesticide applicator. Lawn and landscape care companies that offer fungicide services do so under the supervision of licensed pesticide applicators. Some professional products are illegal for homeowners to apply; others are packaged and marketed such that they are not available to the general public because of package price and availability. Not all products are safe to apply to all plants. Homeowners should check product labels to determine which plants can safely tolerate the product.

Employing a lawn and landscape service for fungicide applications is the best choice for all homeowners. For those determined to make their own applications, please use caution and make informed decisions. Table 1 lists fungicides that have been marketed to homeowners by companies or under brands listed in the second column. Product names will vary and the active ingredient or actual fungicide that is in the product may change as well. Look for the brands below and check the active ingredient on the bottle. Fungicides marketed toward professionals for residential lawn and landscape use are listed in Table 2. Residential lawn and landscape use for many products has changed recently. Homeowners should always check the label on the container they plan to buy before purchasing.

Tables

Table 1. 

Fungicide products marketed toward homeowners for control of landscape plant diseases

Common Name

Brand Name*

Turf**

Ornamentals

Azoxystrobin

Gulf Stream Maxide

X

 

Captan

Hi-Yield®, Bonide®

 

X

Chlorothalonil

Ortho®, Hi-Yield®, Bonide®, Monterey, Dexol®, Fertilome®

 

X

Chlorothalonil + diazinon

Fertilome®

 

X

Copper ammonium***

Fertilome®

 

X

Copper hydroxide***

Fertilome®, Hi-Yield®

 

X

Copper sulfate***

Hi-Yield®, Dexol®, Bonide®

 

X

Fosetyl-al

Monterey

X

X

Lime sulfur

Bonide®, Hi-Yield®

 

X

Maneb

Hi-Yield®

 

X

Myclobutanil

Spectracide®

X

X

Neem oil

Bonide®, Green Light

 

X

Phosphorous acid

Monterey

X

X

Potassium bicarbonate

Bonide®, Monterey

 

X

Propiconazole

Fertilome®, Bonide®, Monterey

 

X

Sulfur

Green Light, Fertilome®, Hi-Yield®, Safer®, Bonide®

 

X

Tebuconazole

Bayer Advanced

 

X

Thiophanate methyl

Green Light, Fertilome®, Scotts®, Bonide®

X

X

Triadimefon

Green Light, Hi-Yield®, Bayer Advanced, Bonide®

X

 

Triforine

Ortho®

 

X

Note: Availability varies. These products are generally available at reasonable prices and in small quantities but often contain some of the same active ingredients as products marketed toward professional pesticide applicators (see Table 2).

*Name of the company that produces the fungicides. The company assigns one or more trade names to the individual product based on the chemical composition and intended use.

**Products without turf sites on the label may not be applied to lawns.

***Copper products may burn turf and ornamental plants. Check the labels.

Table 2. 

Fungicide products marketed toward professional pesticide applicators

Common Name

Trade Names*

Turf**

Ornamentals

Azoxystrobin

Heritage®

X

X

Captan

Captan 50W

X

X

Chlorothalonil

Daconil Ultrex®, Chlorostar VI F, Concord DF, Manicure, Chlorothalonil DF, Echo 720

 

X

Chlorothalonil + thiophanate methyl

Spectro 90WG, Consyst WDG

 

X

Chlorothalonil + zinc

Daconil Zn

 

X

Copper hydroxide***

Champion WP, Kocide 2000 TNO

 

X

Copper hydroxide*** + mancozeb

Junction

 

X

Copper sulfate***

Basicop

 

X

Fludioxonil

Medallion

X

X

Flutolanil

Prostar 70 WP, Contrast 70 WP

X

X

Fluoxastrobin

Disarm

X

X

Mefenoxam

Subdue Maxx, Mefenoxam 2

X

X

Myclobutanil

Eagle 40WP, Systhane WSP

X

X

Neem oil extract

Triact 70

 

X

Phosphorous acid

Magellan, Alude

X

X

Potassium bicarbonate

Armicarb, Kaligreen

X

X

Propamocarb hydrochloride

Banol

X

X

Propiconazole

Banner Maxx, Propiconazole Pro

X

X

Sulfur

Sulfur 6L

X

X

Thiophanate methyl

3336 WP

X

X

Triadimefon

Bayleton 50, Strike 50 WDG

X

X

Trifloxystrobin

Compass

X

X

Triflumizole

Terraguard 50

 

X

Note: These products have residential sites (ornamentals or turf or both) on the label and are sold in larger quantities (at much higher unit prices) than those in Table 1. Some of these products prohibit homeowner use (as indicated on the labels). However, lawn and landscape professionals may be able to offer applications of these products as a disease management service to homeowners.

*Where multiple trade names are listed, consult the label to be certain the fungicide is applied to the appropriate plant and site.

**Products without turf sites on the label may not be applied to lawns.

***Copper products may burn turf and ornamental plants. Check the labels.

Footnotes

1.

This document is PP-233, 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 August 2006. Revised March 2011. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

P.F. Harmon, associate professor, Plant Pathology Department; A. J. Palmateer, assistant professor, Tropical Research and Education Center--Homestead, FL; R. E. Ribbeck, former graduate teaching assistant, Plant Pathology Department; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication do not signify our approval to the exclusion of other products of suitable composition. Use pesticides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.