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Research Update:

Bruce Clarke

Extension Specialist in Turfgrass Pathology and Director of the Rutgers Center for Turfgrass Science
Bruce Clarke headshot.
Bruce Clarke.

My research is focused on the identification and control of biotic and abiotic diseases of cool-season turfgrasses. This involves the use of field studies to assess pathogen dynamics, as well as controlled environment and greenhouse studies to ascertain the relationship between environmental stress, cultural management, and disease development. The goal of my research is the development of best management practices for the control of turfgrass diseases such as anthracnose, dollar spot, gray leaf spot, and patch diseases caused by root- and crown-infecting fungi. Results of our research have been utilized by turfgrass managers in the United States and abroad to improve disease control, enhance turfgrass quality and performance, and reduce chemical inputs.

Examples of Current Research Studies

Developing Best Management Practices for the Control of Anthracnose and Dollar Spot Diseases

In collaboration with Dr. Jim Murphy, we have studied the influence of management practices such as fertility, soil pH, mowing, topdressing, cultivation, irrigation, and the use of plant growth regulators on anthracnose disease of annual bluegrass (Poa annua) putting green turf. Through the efforts of our graduate students, we have developed best management practices for the control of anthracnose that have been used to reduce fungicide applications by as much as 80%. Our graduate students are also studying the potential for using disease predictive models, threshold-based fungicide timing, and improved disease resistant cultivars to reduce fungicide usage for the control of dollar spot on creeping bentgrass (Agrostis stolonifera) maintained as fairway turf.

Understanding the Turfgrass Microbiome

In collaboration with Dr. Ning Zhang, we are studying the microbiome associated with creeping bentgrass cultivars with different levels of resistance to dollar spot. The goal of this work is to determine if differences in the microbial community are associated with disease resistance. Our students are also developing molecular tools (e.g., TaqMan qPCR) to detect and quantify the dollar spot pathogen in the field. In addition, they are assessing the pathogenicity, biogeography and management of Magnaporthiopsis meyeri-festucae, a recently identified pathogen that causes summer patch disease on fine fescue (Festuca spp.) turf. This research is being conducted with other faculty and graduate students at Rutgers and several other Big 10 Universities with the goal of improving the performance, quality and sustainability of this low maintenance turfgrass.

Elucidating the Symbiotic Relationship Between Fungal Endophytes and Turfgrass

In collaboration with Dr. Faith Belanger, we are using molecular tools to better understand the mechanism of endophyte-mediated dollar spot resistance of fine fescue turf. In the field, the fungal endophyte Epichloƫ festucae has been associated with resistance to dollar spot in fine fescues. Graduate students in our labs have identified an antifungal protein that appears to be involved in dollar spot resistance and are using CRISPR-Cas9 to help elucidate its function. They are also using next-generation sequencing to obtain transcriptomes of both the endophyte and its grass host to study endophyte-induced choke disease in strong creeping red fescue (F. rubra).

Developing Turfgrasses with Improved Resistance to Disease

My graduate students and I continue to work closely with Drs. Bill Meyer and Stacy Bonos to support their efforts to develop cool-season turfgrasses with improved resistance to fungal diseases. The Turfgrass Breeding Program develops new cultivars with improved tolerance to dollar spot, summer patch, gray leaf spot, brown patch and other important diseases of cool-season grasses.

Methods to Maximize Fungicide Effectiveness

I continue to evaluate new fungicide chemistries and biorational products for the control of important turfgrass diseases in support of the turfgrass industry in New Jersey and surrounding regions. This research focuses on improving disease control, reducing the risk of fungicide resistance, and minimizing fungicide usage. Results of this work are used to update chemical control recommendations which are used by turf managers to optimize disease control on a wide-range of cool-season turfgrasses.