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.

Plant Scientist Urges Proactive Palmer Amaranth Prevention

By Colby Tibbet, Cal Ag Today reporter

Palmer amaranth, aka Amaranthus palmeri S. watson or carelessweed, is an annual herb of the pigweed species that is native to California where it thrives and poses a serious threat to farming.

Amaranthus palmeri S. Watson – carelessweed (Source on USDA Website: Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions.

Lynn Sosnoskie, a project scientist in the UC Davis Department of Plant Sciences who focuses on weed ecology and biology, says Palmer amaranth, spotted on the edge of fields in California, is remarkably aggressive both in growth rate and spread amidst field crops. It develops a lot of wind-blown seeds that spread rapidly.”

“I would suggest that growers in the state of California be particularly diligent about this plant,” said Sosnoskie. “It is a desert annual and is particularly well-adapted to dry environments where it can out-compete, create root growth and achieve stability well. And the recent drought has only escalated the problem.”

“Preventive measures are absolutely essential before this plant becomes established,” continued Sosnoskie. “We found out the hard way in the Southeastern U.S. that Palmer amaranth produces an exceptional number of seeds; if even one plant is missed by applications or escapes regular herbicide applications, that plant can essentially repopulate an entire field.”

“So its absolutely essential that growers here and everywhere become familiar with the weed and remove all plants quickly from a field before it hits reproductive maturity and forms seed,” she said.

Sosnoskie added that some cotton fields in the south have suffered up to 50 percent yield losses and worse. “Some growers have actually abandoned their fields and haven’t harvested their cotton for those years,” said Sosnoskie.

Sources and Resources:

Illustration Source: Amaranthus palmeri S. Watson – carelessweed (Source on USDA Website: Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner’s Sons, New York. Vol. 2: 2. Courtesy of Kentucky Native Plant Society. Scanned by Omnitek Inc. Usage Requirements.

USDA Natural Resources Conservation Service

Palmer Amaranth

Compensatory growth and seed production: A tale of two weeds