Practices used to minimize the use of pesticides

William Gathercole
September 15, 2009
By William Gathercole
Introduction The golf industry exception In order to retain its prohibition exception status in Ontario and Quebec, the golf industry must provide the public, as well as the government, with information supporting the idea that its innovative management practices may reduce the use of pest control products. In the province of Ontario, a requirement for this golf industry exception is the annual report that must be submitted by individual golf clubs.
The following are excerpts from a fact sheet from the Ontario Ministry of the Environment, issued on March 4, 2009, concerning the implementation of the Cosmetic Pesticides Ban Act:

“Annual Report. Owner/operators will be required to prepare an annual report disclosing the locations and amounts of pesticides used on the golf course. (...The golf course...) must provide an explanation of how maintaining accreditation by the IPM body minimized the use of the pesticide ingredients on the golf course and how it will minimize the use during the next year.”

Golf industry policy

Here are excerpts from a golf industry publication on this subject, originating from the board of directors meeting of Canadian Golf Superintendents Association (CGSA), from Feb. 28 through March 1, 2007:

“The CGSA supports (...) protocols and practices related to integrated pest management (...such as...) ways to change conditions to prevent or discourage recurrence of the problem. Examples include: utilizing improved (e.g., drought-resistant, pest-resistant) turfgrass varieties, modifying microclimate conditions, or changing cultural practice management programs. (...) Non–chemical and biological control measures should focus on practices such as the introduction of natural pest enemies (e.g., parasites and predators), utilizing syringing techniques, improving air movement, soil aerification techniques, and mechanical traps.”

Turf disease management

It is possible for the professional turf manager to develop and implement pest control strategies that can significantly reduce the extent of pest problems such as fungal diseases. Turfgrass diseases are usually caused by fungi. These organisms are almost always present in nature, since they can live in dead plants, decaying organic matter, and the soil. When environmental conditions are favourable for disease development, some diseases can be devastatingly lethal to golf courses, sports fields, and even residential home lawns.

Occurrence of turfgrass diseases in Eastern Canada

For the sake of brevity, we have catalogued the various diseases of turf for Eastern Canada only. In the next four segments, golf course diseases are classified as very frequent, frequent, occasional, and rare. A fifth segment also lists those diseases commonly found in residential and commercial lawns, and sports fields.

Diseases that very frequently damage golf course turf 
• Anthracnose Basal Rot
• Anthracnose Foliar Blight
• Curvularia Summer Leaf Blight 
• Dollar Spot 
• Drechslera Melting–Out 
• Fusarium Patch (Microdochium Patch) 
• Gray Snow Mold 
• Pink Snow Mold 
• Summer Patch 
• Take–All (on new construction)
It should be noted that both Fusarium Patch and Pink Snow Mold diseases originate from the same organism.

Diseases that frequently damage golf course turf 
• Algae & Algal Scum 
• Black Layer (frequent or occasional) 
• Brown Patch 
• Damping–Off (on seedlings) 
• Fairy Ring. 
• Powdery Mildew 
• Pythium Blight 
• Pythium Root Rot 
• Yellow Patch

Diseases that occasionally damage golf course turf 
• Bipolaris Summer Leaf Spot 
• Black Layer (occasional or frequent) 
• Coprinus Snow Mold (in Nordic climates) 
• Red Thread & Pink Patch 
• Snow Scald (in Nordic climates) 
• Yellow Tuft (occasional or rare)

Diseases that rarely damage golf course turf 
• Leptosphaerulina Leaf Spot
• Rust
• Slime Molds
• Yellow Tuft (rare or occasional)

Diseases that damage residential and commercial lawns and sports fields 
• Bipolaris Summer Leaf Spot 
• Drechslera Melting–Out 
• Fairy Ring 
• Fusarium Patch (Microdochium Patch) 
• Gray Snow Mold 
• Necrotic Ring Spot 
• Pink Snow Mold 
• Powdery Mildew 
• Red Thread & Pink Patch 
• Rust 
• Slime Molds 

Practices based upon sound science

The following practices of disease “suppression” are valid, but they will not provide disease “control.” The intensity of disease activity may be reduced, but it is improbable that disease will be fully controlled without some use of fungicides. Applications of conventional fungicides will still be necessary, especially preventively, although their frequency may be significantly reduced.

The practices that are employed for disease “suppression” can be classified into issues concerning seven broad categories: 
• Vegetation management
• Fertilization 
• Irrigation 
• Mechanical intervention 
• Mowing 
• Soil management 
• Other practices 
The following details will provide recommendations to the turf manager in the form of an action plan for minimizing the use of fungicides, especially on the golf course.

Vegetation management — general considerations

Mature trees, forests, and other types of dense vegetation will contribute to poor air circulation and shade, leading to a reduction in turfgrass health.

Dense vegetation surrounding turf will increase turf susceptibility to the following diseases on just about every type of turfgrass location, from golf course turf to residential home lawns: 
• Drechslera Melting–Out 
• Powdery Mildew 

Disease problems can be reduced if plants are pruned to allow more sunlight to reach turf, and to permit greater air circulation.

All fine–leaved fescues will tolerate shade when soil conditions are dry and/or well–drained. If soil conditions are humid, irrigated, and/or poorly–drained, a mixture of fine–leaved fescues with rough bluegrass (Poa trivialis) is often recommended.

On the matter of Kentucky bluegrass, varieties with improved performance against shade and associated diseases would be a definite advantage in a disease management program.

Here are examples of Kentucky bluegrass varieties with improved resistance to shade and/or Powdery Mildew: 
• Abbey 
• Absolute 
• Alpine 
• Arcadia 
• Arrow 
• Avalanche 
• Award 
• Brooklawn 
• Cheetah 
• Everest 
• Impact 
• Liberator 
• Midnight Star 
• NuGlade 
• Rugby II 
• Showcase 
• SR–2284 
• Sudden Impact

Vegetation management — golf course conditions

Practically every golf course has at least one or two “problem” putting greens that are chronically “sick” due to the dense vegetation surrounding it. Such vegetation will provide excess shade and will restrict the air circulation, which will lead to a reduction in turfgrass health. The conditions that promote poor air circulation and shade are caused by mature trees, forests, and other types of dense barriers of vegetation. 

Poor air circulation will increase turf susceptibility to the following diseases, specifically on golf course turf: 
• Anthracnose Basal Rot 
• Anthracnose Foliar Blight 
• Pythium Blight

In such cases, disease problems can be considerably reduced when vegetation is not allowed, and ultimately removed, within at least 30 metres (100 feet) from the edge of the putting green surface. 

Fertilization — practices and products

The implementation of the following fertilization practices and the use of products will influence the development of disease activity: 
• Using a balanced ratio 
• Using nitrogen at necessarily high levels 
• Using nitrogen adequately before June 1st 
• Using nitrogen at excessive levels 
• Using nitrogen for soil acidification 
• Using nitrogen from organic sources 
• Using nitrogen in water–soluble form 
• Using phosphorus 
• Using potassium
• Selecting turfgrass varieties

Fertilization — using a balanced ratio

Using a fertilizer with a ratio of 3-1-2 (nitrogen-phosphorus-potassium), will decrease turf susceptibility to certain diseases, when compared with nitrogen alone. Examples of fertilizers with a 3-1-2 ratio are 18–6–12 and 15–3–9. These fertilizers will tend to be used on golf course putting greens. At least 50 to 75 per cent slow–release nitrogen is suggested. 

These fertilization practices will decrease turf susceptibility to the following diseases: 
• Fusarium Patch (Microdochium Patch) 
• Red Thread & Pink Patch 
• Take–All 
Fertilization — using potassium

A high–potassium (with high–phosphorus) fertilizer mixture may be used to suppress Fusarium Patch (Microdochium Patch) disease. This disease is common in many parts of Canada. Use a fertilizer with a 3-5-5 ratio, and apply it during the fall months. The closest practical example of a fertilizer with this ratio is 15–20–21. This fertilizer is recommended for most types of turfgrasses. Since Fusarium Patch disease is prevalent under cool and moist conditions, hence at least 50 per cent slow–release nitrogen is recommended.

About the principal author

William H. Gathercole holds a degree in horticulture from the University of Guelph, and another pure and applied science degree from McGill University. He has worked in virtually all aspects of the green space industry, and has overseen or managed tens of thousands of turfgrass locations, including golf courses, sports fields, and residential home lawns. Mr. Gathercole has been a consultant and instructor for decades. He is a contributing columnist for Turf & Recreation.

Personal note and disclaimer

In sickness or in health, with the help of his entourage, we still hope to keep all of our readers entertained and informed. Bill continues to recover from his serious motor vehicle accident. In order to complete this particular article, it has been co–authored with Norah G. Well–wishers may send a personal note to Bill by way of this magazine, or by This e-mail address is being protected from spambots. You need JavaScript enabled to view it . By the way, the opinions expressed in this article, even though from an independent perspective, may not reflect those of Turf & Recreation.

References for readers that are curious–at–heart

Although every item found within this article has been carefully researched, there is no exhaustive list of references since this is not a scientific journal. And besides, the sheer number of references and documents that were used to support this article are far too numerous to list within the confines of this magazine. However, the authors will provide references to any reader that requests them. Please send your request to This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

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