Integrated disease management on winter sports turf
The aim of this study was to formulate an integrated disease management (IDM) strategy for winter sports turf. (Winter sports turf, or coarse turf, consists primarily of perennial rye grass, Lolium perenne, which is used for football, rugby and hockey pitches because of its wear tolerant characteristics). IDM involves the use of a number of control strategies to suppress disease economically and efficiently. Such strategies incorporate cultural, biological, genetic, legislative and chemical control. In order to formulate a successful disease management strategy, all the significant diseases affecting winter sports turf and the effects of different management strategies on these target pathogens needed to be identified and collated. This was achieved by a comprehensive questionnaire survey to professional football clubs (who require a high level of turf maintenance) and local authorities (moderate/low maintenance). The questionnaire sought information regarding disease, pest and weed incidence, control measures employed and general problems, e. g. drainage, wear and routine management practices. Red thread, Laetisariafiiciformis, and Fusarium patch, Microdochium nivale appeared to be the most ubiquitous diseases on winter sports turf. Some important management practices that suppress red thread can, however, encourage Fusarium patch, e. g. the application of nitrogenous fertiliser. A series of experiments and field trials have been initiated to identify a number of specific factors which manage to effectively suppress both diseases. A field trial involving the use of species mixtures, perennial rye grass and smooth stalked meadow grass (Poa pratensis), illustrated that genetic diversity can help to reduce both red thread and Fusarium patch compared to turf grown in monoculture. The amount Fusarium patch and red thread cover indicated that disease severity was significantly lower in dual species stands as compared to monoculture. A mixture comprising 50% perennial rye grass and 50% smooth stalked meadow grass appeared the most effective at suppressing disease incidence. Similarly, mixtures of three perennial rye grass cultivars appeared more successful at suppressing slight outbreaks of red thread as compared to bi-blends and monoculture. In addition, individual perennial rye grass cultivars also vary in tolerance to red thread. One hundred and ten cultivars, under three different nitrogen regimes were assessedto determine which were the most disease resistant. The cultivars, received artificial football type wear treatment throughout the winter, to determine if red thread incidence predisposes rye grass to be less wear tolerant. The results indicate that a number of cultivars tolerant to red thread throughout the summer were also more resistant to wear. These cultivars included Quickstart, DelDwarf and Brightstar. Wear tolerance was also increased under a moderate nitrogen level (150 kg/ha/yr). Finally, a field trial investigating the effect of nitrogen rate on red thread and Fusarium patch incidence on five different constructions for football pitches was set down. Both diseases appeared to be efficiently suppressed under a moderate/high nitrogen level (N=225 kg/ha/yr). The 'pipe/slit' construction type also appeared to contain both diseases effectively, whilst sustaining a healthy, vigorous sward throughout the Winter when subjected to artificial football-type wear treatment. In addition to the field studies, an investigation to isolate potential microbial antagonists for use as biocontrol agents against Fusarium patch was undertaken; Fusarium patch was identified as the most economically important disease on winter sports turf from the original survey. A number of known antagonists and indigenous fungi and bacteria isolated from the phylloplane and rhizosphere of Lolium perenne were screened in vitro on turfgrass extract agar against Fusarium patch. This in vitro assay identified which species effectively suppressed disease growth. These potential antagonists were further tested in vivo to determine efficacy under field conditions. Fungi from the genus Trichoderma and bacteria from the genera Bacillus and Pseudornonos appeared the most effective antagonists against Fusarium patch in the in vivo study. In all cases where an antagonist was present, Fusarium patch severity was significantly lower than the untreated control, e. g. the indigenous Bacillus sp. reduced disease severity by 76.1 %. The results obtained from the field trials are encouraging and suggest that the use of species/cultivar mixtures, disease tolerant cultivars and a balanced fertiliser regime on a freely-draining construction type can successfully be incorporated into an IDM plan. An IDM strategy will help to effectively suppress both red thread and Fusariurn patch on winter sports turf. Biological control of Fusariurn patch was successful on an experimental basis, although further research is required to identify an appropriate formulation and optimum application technique for successful commercial use. The use of IDM on winter sports turf will help reduce reliance on chemical control, may delay the onset of fungicide resistance and reduce non-target impacts of fungicides. IDM will also help limit the need for potentially hazardous chemicals in recreational areas open to the public.