Submitted by James Crawford, University of Missouri Extension



Kaitlyn Bissonnette has spent her first year at the University of Missouri traveling throughout the state to meet with farmers and producers to discuss what diseases they are dealing with in their fields.
Bissonnette joined MU in October 2017 as an assistant Extension professor in the Division of Plant Sciences. Her program is focused on the management of diseases of economically important field crops, particularly corn, soybeans and wheat. Her main objective is looking at fungicide resistance management.


“The proper management of fungicides is critical so we don’t have more issues in the long run,” Bissonnette said. “It’s similar to herbicide resistance management. The more we use fungicides to combat a problem, the more we expose the pathogen to the fungicide, and that leads to an increased likelihood that certain pathogens will develop resistance.”
Bissonnette has been busy lately, as the MU College of Agriculture, Food and Natural Resources’ (CAFNR) field day season is officially underway. Bissonnette has been a regular at these events, presenting on common diseases found in Missouri, as well as having conversations with farmers and producers.


“Extension is my thing,” she said. “It’s what I was born to do. The excitement can’t be described. I’ve really enjoyed getting to meet everyone so far.”
Bissonnette is a third-generation Extension plant pathologist. Her grandfather was an Extension plant pathologist at the University of Minnesota, and her aunt is Suzanne Bissonnette, the assistant dean for agriculture and natural resources for University of Illinois Extension.


“My interest in disease began as a kid when I was simply looking at powdery mildew on some lilacs,” Kaitlyn Bissonnette said. “I was just curious what was going on. That’s truly where it all began. I grew up in a suburb of Minneapolis, so I didn’t have the traditional agriculture background and experiences. But I fell in love with it through some great opportunities.”
The focus of Bissonnette’s presentations during this field day season is on disease issues that may show up throughout the year. While Missouri has experienced drought-like conditions throughout the summer, Bissonnette said there are some common diseases that can still be present.


“This year, since it has been very dry, there are certain diseases that could show up, but many won’t,” Bissonnette said. “My goal has been to really emphasize the most common diseases, as well as which diseases require fungicides for management and which don’t.”
Bissonnette will be speaking during the upcoming Graves-Chapple Research Center field day, which will run from 7:30 a.m. to 11:45 a.m. on Tuesday, August 28. She will spend some time talking about frogeye leaf spot in soybeans, as well as a few other common diseases. Bissonnette has received reports of frogeye leaf spot issues in the northwest part of the state.


“Even with the dry year, we’ve had reports of frogeye leaf spot,” she said. “It’s actually really strange since it’s not been wet.”
The spores of the pathogen that causes frogeye leaf spot land on the plant, germinate and cause lesions that are generally round with a gray to brown center and reddish purple margins. These spots can continue to form throughout the season on newly emerging leaves if the conditions are right, eventually damaging the plant and resulting in yield loss.
“One of the biggest problems with frogeye leaf spot in Missouri is that fungicide resistant isolates of the pathogen have been detected in the southeast part of the state,” Bissonnette said. “This pathogen also produces a lot of spores and can progress quickly.”


That’s why Bissonnette encourages fungicide resistance management. While fungicides play an important role in the controlling of disease, overuse or misuse of those fungicides can result in resistance development.
“We emphasize preventative more than curative,” Bissonnette said. “Curative applications tend to increase the risk of resistance development. We want to stay ahead of the curve.
“We also emphasize multiple modes of action. Just because a pathogen has fungicide resistance, doesn’t mean it’s resistant to all fungicides. It’s important to apply a mix. Thankfully, most of the fungicides on the market today are not a single mode of action.”


Proper identification of disease is also an important step in the process. Bissonnette said the developmental stage of the plant and its resistance level play a role in management decisions.
“The developmental stage of the plant at which a disease begins to develop plays a critical role in making management decisions,” Bissonnette said. “You also have to be aware that there are some diseases that look similar to others – or can simply be herbicide damage or nutrient stress. Proper identification is vital, and I’m always happy to answer any questions related to disease.”


Bissonnette earned her bachelor’s degree at the University of Minnesota, her master’s degree at the University of Idaho and her Ph.D. at the University of Illinois.
“We’re glad to have Kaitlyn speaking during this year’s field day,” said Jim Crawford, superintendent of the Graves-Chapple Research Center. “She has been doing a great job of making connections across the state, and she is playing a vital role in the fungicide resistance management conversation.”