Take-all patch is a significant disease that primarily affects Agrostis spp. in temperate regions worldwide. The causal agent of the disease is Gaeumannomyces avenae, which can also infect Festuca and Poa spp., although these species typically experience less severe damage and are able to survive in areas where Agrostis spp. have been affected.

Causal agents

Gaeumannomyces avenae

Primary Hosts

Creeping bentgrass (primary) as well as Festuca and Poa species (secondary)

Disease Cycle

Gaeumannomyces avenae survives as mycelium in previously infected plant tissue. Infection of host roots, stolons, rhizomes, and crowns occurs during autumn and spring. Ectotrophic runner hyphae colonize the surfaces of host roots, giving rise to simple hyphopodia and mycelial mats that initiate infection of the root cortex. Under favorable conditions, extensive colonization of host tissues can occur. Aboveground symptoms typically appear in late spring or early summer when heat or drought stress causes a decline in infected plants. Severe cases may show symptoms in both autumn and spring. The pathogen is likely spread through the transport of infested soil or plant material. Perithecia may be produced in autumn and possibly mild winters. The importance of ascospores in disseminating the pathogen in Agrostis spp. is unknown.

Epidemiology

Take-all patch is most damaging in Agrostis spp. planted in fumigated soil, on recently cleared forested sites, or in substrates with a high sand content. Soil conditions that favor the disease include the following:

• light texture
• low organic matter content
• low or unbalanced fertility
• manganese deficiency
• pH above 6.5

The disease is more strongly associated with rhizosphere pH than bulk soil pH. Liming can promote the disease, especially when fine particle size lime is applied. Take-all patch is most severe when cool, wet weather in autumn or spring is followed by hot, dry conditions. Over time, the disease may decline in severity due to the buildup of antagonistic or competing microorganisms. In some cases, take-all patch can intensify over several years or longer.

Symptoms

Symptoms of take-all patch typically appear as small, circular patches with light brown or reddish-brown colors. These patches can expand up to 15 cm (6 in) per year and reach diameters of 1 m (36 in) or more. The peripheries of patches, or sometimes the entire patches, may turn reddish-brown or bronze. In mixed stands, affected grasses may appear yellow-brown to brown, resulting in a thinned stand dominated by other grass species. Symptoms become more striking after plants have been stressed by hot, dry weather in late summer, with affected grasses turning bronze to reddish-brown and eventually fading to a dull brown. During winter, affected patches may appear gray.

Credit: John Kaminski/Penn State University

Signs

Dark strands of ectotrophic hyphae with simple hyphopodia colonize the root surfaces, and dark brown perithecia may develop in leaf sheaths around crowns and stem bases. Long, multiseptate ascospores are contained with asci.

Credit: John Kaminski/Penn State University

Management

Take-all patch is a damaging disease that affects turfgrass, posing a significant challenge to turf managers and homeowners. This fungal disease primarily targets the roots of turfgrass, leading to root rot, decline, and thinning of the turf. Managing take-all patch requires a comprehensive approach that combines cultural and chemical strategies to suppress the disease and promote turf recovery. By implementing effective management practices, turfgrass managers can mitigate the impact of take-all patch and maintain healthy, vigorous turf stands.

Cultural

An integrated management approach is recommended for the control of take-all patch. Planting a mixture of Agrostis spp. and Festuca rubra can help reduce disease severity. It is important to maintain soil pH below 6.5, preferably within the range of 5.5-6.0, by using acidifying fertilizers and avoiding alkaline topdressing materials and nitrate forms of nitrogen. Monitoring the pH of irrigation water is also recommended. Supplemental applications of manganese can be effective in reducing disease severity on manganese-deficient sites. Proper application of phosphorus and potassium based on soil tests or tissue analyses is important. Avoiding excessive irrigation and nitrogen applications, providing adequate drainage, and aerifying the turf to alleviate soil compaction are essential for reducing the severity of the disease.

Chemical

To control take-all patch, fungicides should be applied preventively in at least 5 gallons of water per 1,000 square feet, or followed immediately by 0.125-0.25 inches of irrigation to wash the fungicide into the root zone. Granular fungicides should be applied on dry turf and then watered into the soil. For outbreaks that develop during the spring, the most critical time for preventive fungicide treatment is from mid-September to early-November when the average soil temperatures at a 2-inch depth range from 45-60°F (7-16°C). Severe disease pressure may require additional fungicide applications at 21- to 28-day intervals starting in early April.

GPS sprayers can be utilized to target fungicides specifically to infested areas, potentially saving costs. If symptoms worsen during the summer, treatments in spring are often necessary when the springtime soil temperature at a 2-inch depth average over five days exceeds 55°F (13°C). Curative applications of effective fungicides in early-summer have been shown to speed up turf recovery, but mid-summer applications are rarely effective.