Recipient Organization
RUTGERS, THE STATE UNIVERSITY OF NEW JERSEY
3 RUTGERS PLZA
NEW BRUNSWICK,NJ 08901-8559
Performing Department
Plant Biology
Non Technical Summary
Turfgrass landscapes cover approximately 50 million acres of land in the United States and provide numerous environmental, recreational, and economic benefits. The 14,000+ golf courses present in the U.S. only account for approximately 5% of the total turfgrass area; however, the golf industry is estimated to contribute over $84 billion to the U.S. economy. The intensive practices required to maintain putting greens, fairways, and tees on a golf course can have a significant economic impact on golf course management.Dollar spot, caused by a group of fungal species from the genus Clarireedia, infect the leaves of turfgrass plants and causes severe blighting of the foliage in roughly circular infection centers 2 to 5 cm in diameter. Numerous dollar spot infection centers can appear and blight a large area of turf in just a few days. Infection can progress into the plant crown and cause plant death, which leaves sunken depressions in the turf stand detracting from the playability and/or aesthetic value of the affected turf, and ultimately creates voids for weed enroachment. Nearly all grass species that are grown for turf are susceptible and the optimal conditions for dollar spot symptom development (temperatures between 15 and 30°C and high humidity/prolonged leaf wetness) are common in many temperate areas of the U.S. from May until October.Dollar spot is the most commonly observed disease of turfgrasses on golf courses throughout the world. Approximately 70% of U.S. golf course superintendents in the Midwest and Northeast considered dollar spot to be their primary disease, and the average golf course superintendent in these regions spent approximately $15,000 and $28,000, respectively, to control dollar spot. More fungicide is used and more money is spent to control dollar than any other turfgrass disease on golf courses.Research is needed to reduce the reliance on chemical control of dollar spot and prevent new cases of fungicide resistance. Outocmes of the proposed research will be financially advantageous to golf course facilities; reduce the risk for development of multi-class fungicide resistant populations of Clarireedia; and decrease concerns surrounding the non-target impacts of fungicide usage on human and environmental health.This research project will:Improve our understanding of how the dollar spot pathogen grows and develops on turfgrass.Assess disease tolerance among turfgrass varieties and identify and overcome barriers to the utilization of improved. disease-tolerant grasses.Develop best management practices (e.g., fertility, rolling, topdressing, irrigation) to limit dollar spot damaged on turfgrass.Develop chemical application strategies that control the disease while reducing chemical inputs and limiting development of fungicide resistant in the pathogen population.
Animal Health Component
50%
Research Effort Categories
Basic
20%
Applied
50%
Developmental
30%
Goals / Objectives
Improve our understanding of dollar spot biology and epidemiology through taxonomic analysis, molecular assay development, and host-pathogen interaction research.
Assess current dollar spot resistance among bentgrass cultivars and new selections, identify barriers to their utilization in golf course establishment and renovations, and develop strategies for overcoming the identified barriers.
Develop cultural-based dollar spot management strategies that combine multiple cultural practices (e.g., fertility, rolling, topdressing, irrigation) to limit dollar spot development in multiple geographic regions.
Develop integrated and targeted chemical dollar spot management strategies that maintain current levels of disease control, potentially reduce chemical inputs, and limit development of fungicide resistant populations.
Project Methods
Objective 1: Improve our understanding of dollar spot biology and epidemiology through taxonomic analysis, molecular assay development, and host-pathogen interaction research. Rutgers will provide pathogen isolates to be used to assess the recent taxonomic assignments established by Salgado-Salazar et al. (2018). In addtition, dollar spot occurring during the fall months appears to have increased in severity and differential responses to creeping bentgrass resistance screening has been observed in the spring vs the summer vs the fall (e.g., fall isolates appear to cause extensive damage [deep pitting of the turf surface] compared to spring and summer isolates). Researchers at Rutgers will collect dollar spot isolates during the spring, summer and again during the fall for taxonomic/molecular analysis at USDA and Rutgers. In vitro temperature and fungicide sensitivity analysis will also be conducted, which will guide development of temporal-based field studies at multiple universities from distinct geographic regions. Epidemiology research will continue by researchers at Rutgers to develop a molecular assay to quantify the dollar spot fungus in the plant (leaves and thatch) pre-symptomatically. This assay should be completed in 2020 and can be used to conduct epidemiological assays related to pathogen dispersal, overwintering, and response to cultural and chemical controls. Select field studies using this molecular assay will begin in 2020.Objective 2: Assess current dollar spot resistance among bentgrass cultivars and new selections, identify barriers to utilization in golf course establishment and renovations, and develop strategies for overcoming the identified barriers. Multiple creeping bentgrass cultivars have been developed at Rutgers University, Michigan State, and elsewhere in recent years with improved resistance to dollar spot. Researchers from Rutgers will provide an updated list of the most dollar spot resistant bentgrasses and identify genetic, environmental, and economic barriers to their inclusion in new bentgrass establishments. Rutgers will contribute to a survey of golf course superintendents from each region of the country to be conducted to identify industry barriers in addition to those identified by the breeders. Goals will be established to overcome these barriers so that improved dollar spot resistance will continue to be a priority in new bentgrass establishment. Rutgers University has initiated trials to determine the economic and environmental impact of transitioning to a more resistant bentgrass cultivar through reduced pesticide usage, and these trials will be continued. The results will be used to provide a more accurate representation of the potential costs and benefits for golf courses considering transitioning to resistant bentgrass cultivars as a means of encouraging the use of bentgrasses with improved resistance to this disease.Objective 3: Develop cultural-based dollar spot management strategies that combine multiple practices (e.g., fertility, rolling, topdressing, irrigation) to limit dollar spot development in various regions. Cultural practices that show the promise regarding dollar spot suppression will be identified. Field studies will then be established at Rutgers to determine how each practice reduces dollar spot individually and in combination with the other cultural practices relative to a fungicide program. The field studies will be conducted over multiple years in each location and data will provided to multi-state colleagues that will conduct an economic analysis to determine cost comparisons of the best cultural practices identified relative to traditional fungicide programs. Upon completion a list of best management practices will be developed to educate golf course superintendents on the impact that each cultural practice and the accumulation of multiple practices has on dollar spot severity.Objective 4: Develop integrated and targeted chemical dollar spot management strategies that maintain current levels of disease control, potentially reduce chemical inputs, and limit development of fungicide resistant populations. Researchers at Rutgers will continue to evaluate current and new fungicides and application strategies (rates, intervals, rotational programs) for dollar spot control. These results will be shared at Rutgers turfgrass research field days, in technical research reports, trade publications, and the peer-reviewed publication Plant Disease Management Reports. Results will be used to update the dollar spot fungicide efficacy rankings published by the University of Kentucky, Rutgers University and the University of Wisconsin in the annual 'Chemical Control of Turfgrass Diseases' (http://www2.ca.uky.edu/agcomm/pubs/ppa/ppa1/ppa1.pdf). Researchers at Rutgers have conducted initial analysis into the feasibility of using a risk index logistic regression model to predict dollar spot activity.Recently completed evaluations of the risk index model in NJ indicate that alternate action thresholds of the model's output (risk index) may be useful in further reducing the number of fungicide applications while maintaining commercially acceptable levels of dollar spot control. Specifically, a larger (>20%) risk index to guide fungicide applications should be appropriate for cultivars that are more tolerant of dollar spot; additionally, changes in the risk index over time (slope; increasing or decreasing risk index) also appear to be predictive of dollar spot activity. Thus, Rutgers will evaluate alternate thresholds and/or slope of the risk index should be evaluated for use in guiding fungicide applications and improving disease control.Dollar spot epidemics differ in incidence and severity among creeping bentgrass cultivars and tend to occur earlier in the year in highly susceptible cultivars compared to moderately susceptible cultivars. Rutgers will determine the feasibility of using threshold-based fungicide applications on fairways to control dollar spot disease across a range of host (bentgrass cultivar) susceptibility and evaluate the economic differences in annual fungicide inputs related to dollar spot susceptibility across bentgrass cultivars