Fighting the turfgrass pathogens fuelled by climate change
Climate change brings winners and losers. Among the winners are the fungal pathogens that cause turfgrass diseases. They thrive in our warmer, wetter climate. But no one’s giving up. We’re working to find more resistant varieties that keep disease at bay. This is the story of the northward march of the pathogens and the turfgrass screening programme that’s holding them back.
Climate changes are elevating turfgrass disease pressure
Climate change – rising temperatures, milder winters, shifting rainfall patterns – is reshaping turfgrass management and the control of turfgrass diseases. The nights are warmer, the air is more humid, and grass leaves stay wetter for longer; our changing climate creates ideal conditions for the fungal pathogens that threaten turf quality. As a result, the incidence and severity of turfgrass diseases are increasing.
Pesticides are no longer an option. The 2009 EU Directive on Sustainable Use of Pesticides has heavily restricted or banned pesticide use. Our response is genetic. To give turf managers the best protection against turfgrass diseases, we look for better varieties. Our screening programme filters out the most resistant turfgrass varieties within our portfolio. It works to meet the emerging needs of turf managers across Europe.
Safeguarding and future-proofing your turfgrass
Adapting to changes in fungal diseases is not straightforward because the turfgrass sector lacks data on resistance. Europe’s official turf lists do not currently include information on resistance to brown patch, dollar spot, or grey leaf spot. In the United States, however, varieties are rated for these diseases as part of the NTEP trials. But this data doesn’t easily translate to European conditions because fungal strains and their pathogenicity can differ widely.
Here at DLF, we monitor disease development closely to deliver the best plant material for these fast-changing times. Breeding new disease-resistant grasses takes time, so we test new breeding materials at the earliest opportunity. Our approach helps turf managers cope with rising disease pressure by safeguarding their turf by choice, not by chance.
Diseases are on the rise
Brown patch (Rhizoctonia solani)
Brown patch is a summer disease that thrives when daytime temperatures range between 20°C and 30°C, and night-time temperatures stay above 17°C. High humidity, prolonged leaf wetness, and poor air circulation create the perfect environment for infection. Brown patch primarily affects perennial ryegrass and tall fescue. Big stadiums with reduced airflow and lush, nitrogen-rich turf are particularly at risk. As summers become warmer and more humid, brown patch is likely to appear more frequently and with greater severity.
Dollar spot (Clarireedia spp.)
Dollar spot, a disease associated with the hot, humid summers of southern and continental Europe, is spreading to northern and coastal regions. The disease shows itself as small, bleached spots that merge into larger patches, severely impacting turf quality. Dollar spot likes warm days, cool nights, and prolonged exposure to dew - conditions that are becoming increasingly common across Europe. The most susceptible turfgrass species include perennial ryegrass and creeping, colonial and velvet bentgrass. Golf greens and other golf areas are particularly vulnerable, as are high-end sports turfs.
Grey leaf spot (Pyricularia oryzae)
Grey leaf spot has become one of the most destructive summer pathogens, particularly on newly seeded pitches and large stadiums with limited airflow. The disease occurs in late summer when daytime temperatures reach 28°C to 32°C and night’s stay above 15°C. Warm, humid weather, high nitrogen levels, and prolonged leaf wetness accelerate infection. Perennial ryegrass and tall fescue are the main hosts, with young turf stands especially susceptible. A series of explosive outbreaks on high-end football stadiums during the hot summer of 2022 shows how easily climate change can affect top-class sport.
Well-known diseases expected to intensify
Pink snow mould (Microdochium nivale)
Pink snow mould develops when turf is snow-covered and also in cool, wet conditions without snow. The pathogen has traditionally been a winter disease thriving in temperatures between 0°C and 10°C with prolonged leaf wetness. Climate change extends the season by giving us milder, wetter winters with fewer hard frosts. The effect is a longer infection window and increased severity, even in areas with little or no snow. The most vulnerable species are creeping bentgrass, perennial ryegrass, and smooth-stalked meadow grass.
Rust diseases (Puccinia spp.)
Rust fungi produce orange-brown pustules that weaken turf and reduce vigour. They prefer moderate temperatures of 20°C to 30°C and extended periods of leaf wetness. So mild autumns and longer, humid summers are likely to make rust outbreaks more frequent and severe. Another contributory factor is turfgrass stress caused by weather fluctuations. The most common hosts are perennial ryegrass, smooth-stalked meadow grass, and tall fescue. Stressed or slow-growing turf is most at risk.
Red thread (Laetisaria fuciformis)
Red thread is a familiar disease in cool, humid conditions, often appearing in spring and autumn when temperatures range from 15°C to 25°C. The disease shows itself as reddish threads or cottony growth on leaf tips. Red thread weakens turf, but doesn’t kill it. Climate change is likely to increase the prevalence of red thread by extending periods of mild, wet weather. Perennial ryegrass and fine fescues are the most susceptible species, particularly in turf that’s stressed or lack nitrogen.
Working together to beat disease
Climate change is not just shifting the calendar, it’s rewriting the turfgrass disease map. Emerging threats come from diseases such as brown patch, dollar spot and grey leaf spot that are moving north, while old enemies – pink snow mould, rust, and red thread – are gearing up for longer, more intense seasons.
For turf managers, it’s a tricky challenge. European pesticide restrictions and gaps in resistance data on official lists limit their choices. Our solution is to provide more resilient turfgrass varieties. By prioritizing our disease screening efforts and breeding, we can work together to maintain great-looking, high-quality turf in a changing world.
You can learn more about diseases and our efforts here.
To find out more about turfgrass varieties with increased resistance to fungal diseases, speak to your local DLF representative.