Detecting SCN with aerial imagery

CARBONDALE, Ill. — The typical methods of determining soybean cyst nematode infestation tend to lack accuracy and efficiency at the field and farm level. Research is underway to change that.

Southern Illinois University is advancing technology capabilities that will provide farmers with a more clear and specific view of SCN population levels, activity and density across their fields, allowing for more precise management.

Jason Bond, SIU plant pathology professor, leads a team in an Illinois soybean checkoff-supported effort that utilizes unmanned aerial vehicle-based remote sensing with multispectral platforms to identify plant stress from SCN infestations.

“One of the things we’ve been working on for a number of years with this project is to develop a tool kit that will assist farmers in determining the real-time stress of SCN in their fields,” Bond said.

“It’s been a long practice in managing cyst nematode to sample the fields and that’s still something that is recommended at least every three to four years to get an update on the level of SCN in those fields. So, you can sample it at the beginning of the year or at the end of the year.

“The uniqueness of this project is using some of those same techniques but also using remote sensing to tell us more about the plant stress and real-time infestation levels of SCN in their fields.

“One of the main benefits is, when we take soil samples it’s generally going to be at a time when we’re out of season or maybe we’re just starting the season. So, you’re pretty far removed from making decisions to manage the organism in that field.”

Filling Gaps

There may be fields that have not been sampled for nematodes for several years, creating possibly a large gap between populations then and now when management decisions are being made for the 2023 growing season.

“The other thing that’s been going on throughout the country is we have more and more counties that are being infested by this nematode,” Bond said.

“Probably in excess of 80% of the fields are infested in Illinois with this nematode, so they are increasing in numbers, not only in a geographical sense but also within a field there’s more numbers in those fields.

“Another thing that’s going on is these populations are even more virulent today than they were even five years ago. So, our resistant varieties that we’re planting today is not enough. They are failing in terms of being able to adequately manage the nematodes by that single process.

“We need multiple ways to manage this organism. We need multiple tools like remote sensing capability to tell us in real time the level of infestation. Not to say it’s going to replace soil sampling, but it would be another tool to go along with the soil sampling to enable the farmers to better manage their fields.”

Collaborative Effort

Ruopu Li, SIU associate professor in geography and environmental resources, noted the project is a collaborative effort with pathologists to determine how drones with multispectral imagery capability can be leveraged to understand the activities in the field.

“We can use the drones to take many snapshots over the different plant periods and to understand how the plant may respond to differential infestation levels of the nematodes,” Li said.

“Essentially, my research group is responsible for collecting the drone images in the field, processing those images, and then do the data analysis. Our methods include image analysis, the geospatial analysis and also statistical analysis, plus the artificial intelligence.

“We want to associate the image with variable infestation level of the nematodes.

“This research project is highly interdisciplinary and collaborative.

“Converting the technologies and expertise from different areas like agricultural science, plant pathology, geography and geospatial technologies are very important to develop the integrated solutions for problem-solving.

“With this collaboration, we can find out that there are so many opportunities to develop technologies and solutions, plus potential fools that can help our farmers tackle these plant pathogens.”

Imagery Bands

Joseph Moses Kalinzi, graduate student in science of geography and environmental resources, said the drone can capture multispectral images of plants using that five bands — red, green, near infrared and red edge.

“When the bands are combined, we come up with what we call vegetation indices. Different vegetation indices show relationships of the activity that is going on,” Kalinzi added.

“The images can be stored on a flash drive. After the data is collected from the field, the data is brought to the lab and stitches all of the images in Pix4D software. After stitching the images, we calculate the vegetation indices,” noted Xian Liu of the SIU Center for Ecology.

Scientific Surprise

“We have two good flight years with data. One of the things that we found in these last two years is when we take samples from the field, the amount of cyst nematodes on a single root system can exceed 80 females just 45 days after planting,” Bond said.

“That bit of information is not really tracked that well in terms of the greater region. We’re not going out and doing root digs necessarily on cyst nematodes across the industry. Again, we take soil samples the beginning of the year and at the end of the year but we’re missing that key component of what’s going on in those very initial stages of a nematode reproduction.

“That’s one of the key findings that we’ve had. It’s just the overwhelming number of nematodes that are attacking the roots and then the virulence in that population is really striking to us, even though we’ve been watching this building up for years, it’s still surprising, even to the scientists.”