A new research wavelength

Leora Radetsky’s background is in lighting research with a non-horticulture (or even horticulture-adjacent) focus; she has been at the Lighting Research Center (LRC) (lrc.rpi.edu) at Rensselaer Polytechnic Institute (RPI) for more than a decade. Dr. Jaimin Patel, meanwhile, is a plant pathologist by trade, having received a degree from North Dakota State University in plant pathology; he started at LRC two years ago. At first glance, Radetsky and Patel would not seem to be two people who would embark on a long-term research project together.

But that is just what they are doing. When Patel joined LRC to bolster the center’s horticultural research capabilities, the goal was for him to embark on projects not being done at other universities or other research centers. And for that last two years, that’s what he and Radetsky have been doing. As a pair, they are exploring how light affects the health of the plants, including physiology.

“We really found that few are working on this area, so there’s a lot of opportunity, and we really think that our mix of physicists, vision scientists, engineers and researchers can really be creative, and test and potentially find solutions,” Patel says.

Research goals

The aim of the research is simple: to see if light can be used as an alternative or adjunct to chemical treatments used to treat pest and disease issues.

“There is some really good research in the literature but in some cases it’s hard for growers to know how to implement it,” Patel says. “We are looking into specialty crops, and considering economics for growers, as a real tactical approach to apply treatment. We want it to be effective to control plant pests and not do damage.”

In the past two years, Radetsky and Patel have only worked on a small number of crops — specifically specialty crops such as cucumbers, herbs and squash. In cucumber and squash, Radetsky and Patel’s research has shown that the ultraviolet light at the right intensity can be effective in treating powdery mildew. But they have also found that light that is too intense can do damage.

“If you overdose the plant, you kill the plants or you damage them. It kills productivity and you don’t get the yields that you want,” Patel says. “If you under dose, or if you don’t give the right spectrum of UV, then it’s not effective either.”

Patel says the key to what they’ve learned so far is understanding how light affects the plant and the pathogen. For example, DNA in the powdery mildew-causing pathogens is damaged by certain UV doses. During the day, both UV and visible light are present in sunlight and the pathogen DNA can repair itself. Applying UV at night prevents the repair mechanisms and allows the optimum dose to be determined.

“In the case of powdery mildew we’re affecting the DNA, whereas [with] other crops that we’re looking at, we are not sure of the mechanisms. We’re finding that visible light has an effect,” Patel says. “In these cases, one outcome measure that we’re looking at is reducing the spores. But we’re just getting started, and there’s a lot more to look at. But what we think is important is that you have a dose response curve, essentially — so how much you need to give, what spectrum, at what time and for how long — and we are looking at the economics of that.”

How the Lighting Research Center works

The LRC, according to Radetsky, works differently than some other research programs. Instead of a land-grant university allotting money each year to different research projects, researchers at the LRC must, for the most part, secure their own funding and set up their own experiments in different facilities. This is in part because of the wide range of topics — many of which are consumer-facing and/or not related to horticulture — the LRC explores.

“As long as I’ve been here at the Lighting Research Center, that has been our model,” Radetsky says. “We primarily operate on this sort of soft-money grant writing. In many ways we are like a business where we have to be efficient and productive in all phases. This keeps us working on real problems and societal benefits.” She adds that the pair also receives financial support from some forward-looking lighting companies such as OSRAM and Cree who have a vested interest in the research yielding positive results about light’s impact on plant health.

According to Radetsky and Patel, they have received a fair amount of help that has helped their research remain ongoing in the past few years. They have access to some greenhouses near their Troy, New York lab for their research and have an indoor growing space at a nearby RPI location. They add that David Gadoury, a senior research associate at the Plant Pathology and Plant-Microbe Biology Section at Cornell University’s College of Agriculture and Life Sciences, has been an invaluable resource as their partner in this research.

“It’s really thanks to him that we embarked on this research,” Radetsky says. “And he’s been working in this area for a long time. Thanks to him, we really got started in this and really started to understand the opportunities.”

They’ve also partnered with the Norwegian University of Life Sciences, Norwegian Institute of Bioeconomy Research and the University of Florida on the research.

“We also get to understand the problem, and not just at the regional level but also at the national and international level,” Patel says. “We’re hearing from different stakeholders to really understand what is going on in agriculture.”

The next steps

Radetsky and Patel both say that their next step is to begin raising awareness for their work and, ideally, to garner more funding for it. When that happens, their plan is to expand their work beyond the produce crops they are currently working with and expand to other specialty crops and ornamentals. They have not yet determined what the first group of ornamentals would be, as it may depend on requirements tied to the funding.

Sometimes they focus their research on one specific pest or disease issue, perhaps even in one specific to a region of the country. For example, a New York State Farm Viability grant was awarded to them to use UV to treat powdery mildew and downy mildew in summer squash.

“We want to make these solutions practical for growers,” Patel says.

“Our team has been funded to look at the impact of light on some economically important specialty crops,” Radetsky says. “Hopefully, as we show results and as we’re able to do more work in this area, we’ll be able to look at other problems in the food chain that we’re very interested in.”