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By Bill Weldon
  • Cornell AgriTech
  • School of Integrative Plant Science
  • Plant Pathology and Plant-Microbe Biology Section
  • Agriculture
  • Plants

Bill Weldon is a graduate student at Cornell AgriTech, studying under the direction of David Gadoury, senior research associate in the plant pathology and plant-microbe biology section of the School of Integrative Plant Science.

What is the focus of your research at Cornell AgriTech?

My research focuses on the fungal pathogen that causes hop powdery mildew, which is a disease that has afflicted New York hop growers since the late nineteenth century. In fact, this pathogen was one of the primary reasons that the hop industry moved westward to the Pacific Northwest immediately following the end of Prohibition. Specifically, I focus on aspects of hop powdery mildew disease ecology and epidemiology so that we may better understand factors such as the unique differences between the pathogen populations of New York and all other hop producing regions throughout the U.S., and ultimately how these differences impact the best disease management strategies for a given location. I also work to understand how winter and early-spring weather conditions affect re-emergence of the disease each spring. Our belief is that the better we can predict when and how intensely the disease will return each season, the more precise and effective we can be in the control measures taken in response.

What’s the most exciting discovery you’d made in your research here?

A recent project in collaboration with Oregon State University and the USDA-ARS has allowed us to pinpoint the primary way in which hop powdery mildew is being introduced into commercial hop yards throughout the Northeast, which is generally through the hop plant material that growers purchase from large distributors. A select handful of powdery mildew susceptible hop varieties appear to be arriving to hop yards infected at levels that are barely detectable, but enough to get the disease established in a hop yard. We were able to come to this conclusion by developing a large collection of genetic “barcodes” that can differentiate samples of the fungal pathogen based on their geographic origin, sort of the same way that the human ancestry DNA services work. We tested these genetic barcodes on a huge, highly diverse collection of hop powdery mildew samples, and see that the mildew present in New York hop yards is genetically similar to that of mildew from the Pacific Northwest hop growing region, which is where the planting material for many of the hop distributors originates. even though there is also a genetically distinct population of hop powdery mildew found growing on feral and wild hops throughout the Northeast. This is critical knowledge for hop growers of New York and beyond because we can now pinpoint the planting of new hops in a hop yard as an extremely critical time to be scouting for powdery mildew, and if you do a good job at that time, you’ll likely stand a good chance of keeping your hop yard relatively free of powdery mildew in the future.

What do you hope the impact of your research will be on New York growers?

I hope that my research will provide New York, Northeast and Midwest hop growers with information and tools that directly improve our applied disease management and prevention strategies toward powdery mildew of hop, with a special emphasis on controlling early spring re-emergence of the disease with great precision. Very often, the better that you are able to control hop powdery mildew early in the season, the cleaner and healthier your hops will be when it comes time to harvest in late August or September. The better that we can control hop powdery mildew, and a second pathogen called hop downy mildew, the better the quality and overall yields of New York hops will be, which ultimately creates more locally sourced hops for the New York state brewing industry to incorporate into their craft beverages.  

What do you think would surprise people most about the subject of your research?

I wish this wasn’t the case, but working with the hop plant from a disease management perspective equips me with very few of the necessary practical skills to brew a good beer from scratch. I’ve learned a lot about the theory behind brewing from many New York state brewers and hop conferences during my time as a graduate student and am slowly getting better with each home brewing batch I make though! 

What’s your favorite memory from your time researching here on the Cornell AgriTech campus?

Being a mentor for undergraduate students participating in the Cornell Summer Scholar’s Program for the past four summers has been a very rewarding experience. I am a former Plant Pathology and Plant-Microbe Biology section summer scholar myself, so know first-hand the power that a really engaging internship experience can have in shaping a student’s future. All four of my former mentees have gone on to pursue a graduate degree in plant pathology and it’s really awesome having been part of the journeys that drew them into the plant pathology field.

Header Image: Weldon, a graduate student at Cornell AgriTech, examines powdery mildew on a hop plant in a greenhouse. Photo by Justin James Muir

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