Invasive weed threatens rice

Groundwork for rice planting is under way in the valley, although rain expected this week may put a damper on farming activities.

Wet ground from recent rain and more on the way could prevent farmers from properly preparing fields for seed, said Luis Espino, U.C. Cooperative Extension farm adviser for Colusa and Glenn counties.

"It's hard to know how much weather we're going to get out of this next system," Espino said Monday. "Spring rain has already delayed groundwork considerably."

Rice is one of the largest crops grown in the North State.

Colusa, Glenn and Yolo counties plant about 280,000 acres of rice each year, or 50 percent of the state's rice acreage, according the U.C. Cooperative Extension.

Although many Glenn and Colusa rice fields are typically planted by the end of April, Espino urges farmers not to rush one very critical step in order to make up for lost time.

"When it comes to groundwork, farmers have to be patient," he said.

Not properly preparing wet, clumpy fields will cause newly planted seeds to get trapped in the crevices or buried in the clay, making it difficult for seedlings to establish themselves, Espino said.

"If we don't get a lot of rain this week, we will probably see tractors racing up and down the fields over the next few weeks," he said.

But there is also more than just wet weather threatening rice this year.

A weed native to South America — and only previously detected in some southern rice growing states —was found in California last fall.

The winged primrose willow was found in a few rice fields in the Richvale area of Butte County, alarming agriculture officials over its possible spread to Colusa and Glenn counties this year.

The weed is highly invasive, produces vast quantities of seeds and survives under a wide range of hydrological and climatic conditions, officials said.

"Farmers have to keep an eye out for this weed, and let us know if they think they have it," Espino said.

The winged primrose willow is an annual, but can behave like a perennial in areas with a moderate climate.

This winged weed should not be confused with other waterprimroses and similar weeds that are usually seen around rice fields and ditches throughout the summer and fall.

Unlike water primroses that grow prostrate on the ground, the winged primorose willow grows erect, officials said.

The yellow flowers have four petals, and the stem has wings or membranes that run longitudinally.

Unlike other waterprimroses, the winged primrose willow can grow within flooded rice fields, which makes it even more problematic for local farmers if it should get established in this area, Espino said.

CONTACT Susan Meeker at 934-6800 or smeeker@tcnpress.com.