Researching essential oils’ potential as bio-fungicide option

By Madelyn Ostendorf

Alexandra Starkey, graduate student in plant pathology, entomology and microbiology, is researching bio-fungicides.

Alexandra Starkey hadn't pictured herself as a plant pathologist, but a chance connection with Leonor Leandro in her senior year sent her off to pursue a doctorate in plant pathology with a minor in microbiology.  
Starkey, graduate student in plant pathology, entomology and microbiology, started as a biology student at Drake University, transferred to Iowa State University to pursue architecture and re-discovered a love for life at the microscopic level.  
"Architecture is beautiful, but just not for me," Starkey said. "I decided to go back to my real, first love - biology. It's the foundation of all life and that to me is just so beautiful." 
Working with Leandro, professor of plant pathology, entomology and microbiology, Starkey's research involves experimenting with bio-fungicides to prevent disease in soybean fields. Her bio-fungicide of choice: essential oils. 
Funding for her research is coming from the College of Agriculture and Life Sciences Innovation in Agriculture Young Scholar Award, which she was recently awarded. The award is provided by the CALS Office for Academic Innovation and the Office for Research and Discovery. 
"I describe my work as volatile aromatic compounds distilled from plants," Starkey said. "That's what essential oils are. The results that we're seeing are just mind-blowing. When we apply lemongrass oil at 0.05%, which is 500 parts per million, there's absolutely no growth of this fungal pathogen." 
Starkey said this isn't the same essential oil you can purchase at a drugstore. It's distilled in the lab at a higher concentration.

Now that she has determined this method of bio-fungicides has an effect against the soil-borne fungus, Fusarium virguliforme, which causes sudden death syndrome in soybeans, the next step is to evaluate different oils to determine which are the most effective.  

Once she has determined that, she will create a field delivery system and evaluate the impact the essential oil has on the soil's microbiome.

"We want to know if it's attacking the fungus or working against the pathogen. We also want to know what it does to the good stuff in the soil," she said. 

In her research, Starkey has worked with professors from several different departments to see the bigger picture of her research, a theory she learned from her time as an architecture student.  

"There's a theory called design thinking," Starkey said. "It means that in order to get the whole picture, you have to include people from outside your bubble. Sometimes as scientists, we get stuck in our line of thinking, and having someone look at the problem from a different perspective gives us exactly what we need." 

Starkey has already shown success with her research on and off Iowa State's campus. 

"Alexandra is doing a fantastic job on her research with essential oils for plant disease management," Leandro said. "She is less than a year into her PhD and has already presented her research results at the national plant pathology conference and at several research symposia on campus."