General Strategies for Disease Management for Landscape Turfgrasses

 

Department of Plant Pathology University of California Riverside, CA 
 

Turfgrass plantings are a common component of landscapes and like other plants, susceptible to diseases. Fungal diseases are by far, the most common disease problems for turf. 

 

Disease results from the interaction of the pathogen, host and environment. Successful disease management results from minimizing one or more of these factors. Although fungicides are often very useful for disease control, their use in the landscape on turf can be limited due to availability (especially for homeowners), cost, or application restrictions. Thus, disease management for landscape turf should be mainly accomplished by cultural management rather than chemical control alone.

 

More detailed information on diseases, insects, weeds and other pests, and cultural practices that encourage healthy turf are available at the University of California Integrated Pest Management website (http://www.ipm.ucdavis.edu)

Choosing a Turf Species

Choosing the right turf type for your environment is very important for maintaining disease free turf in the landscape. Turf types can be grouped into either cool or warm season grasses. Cool season grasses tend to grow best at temperatures of 60 to 80ºF and stay green all year long. Warm season grasses grow best at 80 to 95ºF, but will go dormant as temperatures stay consistently below 50 to 60ºF, with some species turning brown in the fall and winter before greening back up in the spring. Cool season grasses will suffer greatly during periods of high heat or water stress, while warm season grasses are much more tolerant. Diseases tend to occur when the turf is not under optimal growing conditions: cool season grasses tend to get disease when it is hot, warm season grasses tend to get diseases when it is cool.

Unfortunately, many areas in California are known as “transition” zones where no one turf type is perfect. Also, some diseases, such as fairy ring, can attack all turf plantings regardless of the species of turf used.

Cool Season Grasses

Annual Bluegrass (Poa annua)

Although not directly planted, this is an invasive weed that can dominate turf plantings and is common to see mixed into parks, lawns and sports fields. Not drought or heat tolerant, but shade tolerant. Common diseases in California include anthracnose, fusarium blight, rust and summer patch. 

Bentgrass (Agrostis spp.)

These turf types are really not used for landscaping at all, but quite common on golf course greens, especially creeping bentgrass (A. palustris). Moderately drought tolerant, but suffers in heavy shade. Common diseases in California are dollar spot and take-all patch. 

Kentucky Bluegrass (Poa pratensis)

This turf tolerates some shade, but not high heat or drought. Kentucky bluegrass is usually sold as a blend of different varieties, or mixed with perennial ryegrass. The lack of heat and drought tolerance make it especially susceptible to summer diseases. Common diseases in California include anthracnose, leaf spot, fusarium blight, Rhizoctonia blight, rust, and summer patch.

Perennial Ryegrass (Lolium perenne)

This turf is common as overseeded turf on dormant warm season grasses and mixed in with Kentucky Bluegrass, although it can be planted by itself in cool climates. It is used more frequently than annual ryegrass (P. multiflorum). It has low heat and drought tolerance and can tolerate some shade. This turf suffers under high heat and is susceptible to a number of diseases in warm weather. Common diseases in California include leaf spot, Curvularia blight, grey leaf spot, Pythium blight, red thread and summer patch.

Tall Fescue (Festuca arundinacea)

This fescue is the most widely used of the fescue species. Other fescues tend to be used in special situations, but tall fescue is very common in landscapes and lawns. The turf is moderately heat, drought and shade tolerant, making it good as a year round grass in many locations. Common diseases in California are Rhizoctonia blight and rust. 

Warm Season Grasses

Bermudagrass (Cynodon dactylon)

Common (seeded) and hybrid (stolonized) species are used frequently in the landscape. They are generally low maintenance, but have a tendency to become weedy invaders for flower beds and other areas and go brown in the winter. Drought and heat tolerant, but suffers in shade. Common diseases in California are leaf spots, Rhizoctonia blight, and spring dead spot. 

Kikuyugrass (Pennisetum clandestinum)

Another invasive weed that becomes managed as landscape turf, although a seeded variety is commercially available. It has good heat, drought and shade tolerance and often does not go fully dormant in the winter. It grows very vigorously in the summer, which sometimes leads to excess thatch accumulation and accidental scalping. Common diseases in California include Kikuyugrass decline, Rhizoctonia blight and gray leaf spot.

St. Augustinegrass (Stenotaphrum secundatum)

This turf type is not very common in California now, but was more popular in the past. It has good heat, drought and shade tolerance; although it goes dormant in cold weather, it does not often turn brown in California. Common diseases include take-all root rot and gray leaf spot.