Are California's agronomic crops a source of the state's weed problems?

Affirmative, says Robert Stewart, field services manager of the California Crop Improvement Association at Davis, and speaker at the recent 53rd Annual Conference of the California Weed Science Society.

However, he explained at the gathering in Monterey, the CCIA is alert with rigorous, seed-quality programs to curtail contamination of agronomic crops by noxious weeds.

Stewart traced the CCIA from its origins in 1920 as the California Improved Seed Program, a cooperative project of the California Farm Bureau and the University of California.

Until 1940, seed fields were evaluated by pure-seed leagues on a county basis, actually committees rather than individual inspectors of today.

By 1944, those seed-certification functions had gathered under the CCIA, the non-profit, seed-certification agency for the state. In the early years it dealt mainly with clovers, small grains, beans, rice and alfalfa.

Standards were developed to ensure seed stock to the industry having the purity of varieties released by land grant universities.

`Paper-work trail' Certification is a system of record keeping, standards, and inspection, or as Stewart put it, "a paper-work trail of identification, segregation, growing, harvesting, conditioning, bagging, and tagging for quality of each and every seed lot."

Growers are keenly aware that good seed control for seed production starts with a clean field. If not all weeds, certainly weeds considered noxious to the particular crop need to be controlled. Examples of noxious weeds are cocklebur in cotton, nightshade in beans, and wild oats in grains.

In recent years, CCIA field inspectors look at averages of more than 175,000 acres of 30 different crops. Five major crops - cotton, alfalfa, rice, sunflower, and wheat - comprise more than 75 percent of the state's certified seed acreage.

In 1999, CCIA certified more than 140 varieties of alfalfa, seed production of which is concentrated in Fresno and Kings counties. Of the seed exported, a majority finds its way to South America, Africa, and Europe.

The CCIA alfalfa seed quality program demonstrates the thorough seed-testing regime. In 1995 the state had 35,000 acres of alfalfa seed. From 661 samples surveyed that year, CCIA rejected 45 samples for weed seed content, 39 of them for dodder seed.

In 1999, from 65,000 acres the association received 1,590 samples, rejecting nearly 350 of them mainly for dodder, alkali mallow, johnsongrass, yellow star thistle or sour clover seed.

Some lots from 1999 were rejected for dodder content once, re-cleaned, and tested again. The state produced more than 40 million pounds of alfalfa seed that year.

"When we have higher acreage of any of our seed crops, the quality coming into our lab seems to deteriorate. I believe that's because when prices get high, a lot of marginal ground that may have weed problems is brought into the system," Stewart said.

Regardless, he added, CCIA's field and lab inspections show the majority of all seed lots do comply with standards and minimum requirements designated by the certification program.

"The devotion and hard work of our seed growers in making the California program known worldwide, have allowed our state to maintain its great reputation for producing quality seed."

Credits state rice Stewart credited the California rice industry for its diligence in clean seed. Red rice, the main noxious weed for rice in the U.S., challenges the southern states but is not known to occur in California.

"This is a good example of an industry that has realized the importance of a good seed program and has avoided bringing in a problem which has plagued many other rice-growing areas," he said.

Several crops, including sunflower, have an additional dimension concern beyond potential contamination from weed seeds. In northern California wild sunflower can contaminate genetic purity of commercial varieties, and standards of isolation from known sources are enforced.

From about 5,000 acres of clover for seed in 1999, California growers generated nearly 2.25 million pounds of certified clover seed, or about 90 percent of all clover seed produced in the nation.

In far smaller amounts, CCIA has certified seed for organic watermelons, wild rice, and even the rubber-substitute source, guayule.