Study: Remote Sensing of Weeds on Vineyards Has Merit

Aerial Sensing Of Weeds Saves Time and Labor

By Jessica Theisman, Associate Editor

There is a potential use of remote sensing with drones and vineyard weed management. Working on that research is Cody Drake, a senior at California State University, Fresno. He’s working with Luca Brillante, an assistant professor in the Department of Viticulture and Enology. Anil Shrestha is chair and professor, also in the Department of Viticulture and Enology at Fresno State. Drake’s research is at a vineyard in Napa County.

“The goal of my research is to make weed management practices in vineyards a little more efficient,” Drake said.

Currently, there is a lot of manpower, money, and time going into scouting for weeds and spraying.

“What we did with the drone is we wanted to map high-pressure weed zones to target spray in the field instead of spraying the entire field,” Drake explained.

This aerial scouting is hoping to become more efficient for time and labor.

“It’s all based on imagery. The drone gives us waypoints as to the areas where we need to spray. We have a company that’s called Drone Deploy, and they go through, and they stitch all the photos together,” Drake said.

Drake’s research has only been on vineyards so far, and his research has been proven to work.

“We did a 30-meter flight and a 10-meter flight, and that just shows the difference in how close you can get to identifying weeds species on the ground at a 30 meter height,” he said.

At 30 meters, it was very hard to tell which species was which. At 10 meters, the weeds were more identifiable.

“We would prefer to do another trial with a higher resolution camera. That way we can see the species, identify them a little easier and a little more efficiently,” Drake said.

By doing this, Drake and his team can pinpoint where the heavyweights are and just go spray that one area. For future research, they are going to try a camera with higher resolution to see if it can see through a denser vineyard.

Fresno State Student Studies Palmer Amaranth

Sami Budhathoki Finds Palmer Amaranth Can Adapt to Saline Soils

By Jessica Theisman, Associate Editor
Palmer Amaranth

Sami Budhathoki is in the last semester of her undergrad degree at Fresno State. She spoke with California Ag Today recently about her research on how the Palmer Amaranth can adapt to saline soils in the San Joaquin Valley. Palmer amaranth as among the most troublesome weeds in agriculture because it is a very prolific seed producer and very tough to control due to widespread glyphosate escapes. It is found throughout California.

Her major advisor is Anil Shrestha, a professor in weed science at Fresno State. Budhathoki presented her research at a recent California Weed Science Society Meeting in Sacramento.

“I treated soils with five different salt levels, and I found out that the weed likes that higher salt levels, and they did fine, and they all germinated,” Budhathoki said.

Based on the pictures on Budhathoki’s poster, the Amaranth grew better in soils with higher salinities.

“That gives us the hint that Fresno is more resistant for the Palmer Amaranth plants because the west side has a lot of salt in its soil,” she said.

That is why it is hard to control in those areas, especially because they propagate so easily.

Budhathoki gave California Ag Today more insight on her research.

“Before treating the soil with salt, the plants were all the same height and same size. After the treatment, you can see the differences in how each plant reacted to the salt,” she said.

We asked Budhathoki what it was like working with such a troublesome weed in the ag industry.

“It was my first time working with Palmer Amaranth; it was a good experience,” she said.

Budhathoki says that she thinks there will be more research on this weed in the future so that farmers can find out how to better control it.

Vigilant Seed Bank Reduction for Weed Control

Vigilant Seed Bank Reduction: Whatever it takes, don’t let weeds set seed.

By Patrick Cavanaugh, Farm News Director

 

For the past 15 years, Robert Norris, professor emeritus and vegetable crops weed specialist, UC Davis Department of Plant Sciences, has continued to attend Weed Day each year at UC Davis and to contribute weed photography for CalPhotos, a UC Berkeley Digital Library Project photo database of world-wide plants, animals, landscapes, and other natural history subjects developed to provide a testbed of digital images for computer science researchers to study digital image retrieval techniques. Norris was involved with initiating the Plant Protection and Pest Management Graduate Program at UC Davis.

 

“I’ve been a botanist since I was 14 years old,” Norris said, “and I still have a lot of passion regarding weed control.” Norris has a strong and steady philosophy on weed control and it all comes down to seeds. “The last 25 years of my work, I looked at population dynamics of weeds, like seed longevity in the soil and what we call the size of the seed bank also known as the seed production by weeds. That’s really where I spent most of my time.

Field Bindweed
Field Bindweed

 

“I found that most people have a very poor idea of how many seeds are produced by a weed. This led me to question some of our current management philosophies; namely, the one that comes out of entomology—the use of thresholds (or how many weeds need to be present before treating them),” noted Norris. “I felt that for weed science, thresholds were not the way to go, and my position has been vindicated by the problems we’ve run into using thresholds.”

 

Norris offered the example, “Barnyard grasses are probably one of our most serious summer grass weeds. A small plant can produce 100,000 seeds; while a big plant, well over a million. I can remember going put in a tomato field years ago and looking at one barnyard grass plant. Because I had been working with it, I can say that plant probably put out 50,000 seeds. If you spread those seeds around an acre, that’s enough to give you serious yield loss the next year,” Norris explained. “Again, that’s one plant, spread out over an acre. Obviously its seeds wouldn’t spread over an acre [on their own], but with our tillage equipment we would move it around quite a bit.”

 

“My bottom line for about 30 years now is: Don’t let the weeds set seed. Whatever it takes, don’t let them set seed,” Norris said. If you follow that philosophy, Norris said after a while you drive the seed bank down.

 

“Many people don’t realize this, but some of our really big growers got on to it a long time ago. One farming operation I worked with for years, J. G. Boswell Co., with most of its land in Kings County. “I knew the manager in the late ’50s, into the ’70s. He now is retired now, but he came to this conclusion himself back in the late ’50s,” Norris said. “I haven’t been on Boswell’s property now for 20 years, because I retired. However, if you go down there, you will not see a weed problem, at least not like most growers.”

 

“The difficulty really is, in order to carry out this philosophy, you need to use hand labor for weed management and it is becoming less and less easy to find,” explained Norris. “Most weed management is done on a one-year one-crop basis; whereas, the type of management we’re talking about where we’re really thinking seed bank dynamics, has to be done over multiple years. Another big problem that I still see is if you miss one year, you can undo 5 to 10 years of what you’ve just been doing, because of this high seed output,” he said.


NEVER LET ‘EM SET SEED, by Robert Norris, Weed Science Society of America.