When California's Mendicino County publishes it annual farm production census this spring, agricultural Commissioner Ted Erickson will dutifully report that wine grapes are the county's No. 1 crop.

That's not true, and Eriksen knows it.

But the Mendicino Board of Supervisors and California state officials have ordered him not to report on the county's most lucrative farm crop -- marijuana.

Marijuana growing is a $100-million-a-year business in Mendicino, Eriksen estimates, so big it makes the county's $20 million worth of grapes look like small potatoes.

After years of ignoring illegal marijuana farming, Eriksen finally included the crop in his annual report last year. He might as well have lit a joint in the courthouse.

There was such a flap that Eriksen had to tear the marijuana page out of every issue of his annual report and promise never to report on pot again.

"A lot of people feel that if you don't mention it, it'll go away," says Eriksen. "The fact is that this is an illegal crop, but it has tremendous impact on the economy of Mendocino County."

Mendocino is one of 17 northern California counties in which Marijuana farming has reached such a scale that federal agents have been sent in to try and stop it.

Until recently the marijuana business was dominated by imports, primarily from Columbia.

But while U.S. steel and automakers are pleading for protection from imports and the nation's producers of shoes and television sets are strugglingto survive against foreign competition, the domestic pot industry is proving it can beat the imports.

American Marijuana growers harvested a record crop last year, well over 1,000 metric tons of the illegal herb, federal authorities and private marijuana specialists estimate.

Federal Drug Enforcement Administration statistics released a few days ago show U.S. marijuana production growing at a rate of better than 20 percent a year, while marijuana imports are up only about 13 percent.

The agency estimates Americans smoked marijuana worth between $15.5 billion and $21.9 billion in 1979.Perhaps $2 billion to $3 billion worth was grown in the United States. By comparison, U.S. tobacco production was worth $17 billion that year.

Once considered a youthful indulgence, marijuana has gained increasing acceptance among adults, the DEA said. Use of the drug by youths 12 to 17 is "leveling off" the agency reported, but "there was an unexpected persistence in marijuana use between 1977 and 1979 among older adults (over 26) who used Marijuana in their youth."

The rapid growth of marijuana cultivation has for the first time forced the DEA to switch some of its law enforcement effort from trying to stop smuggling and to concentrating on catching domestic producers.

Commercial marijuana growing began in the United States only about five years ago, and already homegrown pot accounts for an estimated 7 percent to 10 percent of the 14,000 to 15,000 tons smoked each year.

Measured in dollars, the domestic pot growers have captured an even bigger share of the market, because their product sells for two to 10 times as much as imported marijuana.

As if they had taken a percentage lesson from Madison Avenue, U.S. marijuana farmers are cashing in by concentrating on the luxury market -- producing what even the DEA admits if the best marijuana available and charging premium prices for it.

Domestic growers have used designer genitics to produce pot many times more potent than garden-variety grass. They've even given it what amounts to a brand name -- "sinsemilla." The word is an amalgam of the two Spanish words meaning "seedless" but has come to imply champagne-quality homegrown marijuana. U.S. growers are getting $100 to to $200 an ounce for their sinsemilla, while Columbian grass sells for $40 or less.

And because the channels of distribution are much shorter for American marijuana -- much of it is sold directly by the growers -- the domestic producers are making far greater profit.

On an investment of $3,000 or less, a grower can easily produce a marijuana crop worth $100,000, says David Schickedanz, coordinator of the first federal effort to try to eradicate the infant industry before it gets any bigger.

Between June and October of last year, local, state and federal agents participating in the DEA's "Operation Sinsemilla" raided 740 pot plots, arrested 527 persons and seized 129,329 marijuana plants weighing more than a total of 220,000 pounds.

Counting another ton of processed pot that was seized, the operation netted an estimated $131.5 million worth of marijuana.

All the seizures and arrests were made in 17 norther California counties (including Mendocino) where serious marijuana growing apparently got its start and is the most prevalent.

California and Hawaii are the leading marijuana growing states, reports the DEA. "We're not saying it's just Claifornia and Hawaii," stressed Schickedanz. "You'll find it in every state that has a growing season long enough for vegetables. Anybody who can grow a tomato can grow marijuana.

When the DEA began cracking down in northern California, growers moved over the border into Oregon. Arkansas is rapidly building a reputation as California's rival, say officials of the national Organization for Reform of Marijuana Laws (NORML). They contend marijuana is grown in every state and the District of Columbia, where much of it is cultivated indoors.

Campaigning for the right to grow grass for personal consumption is the latest move for the group, which until now has stressed efforts to ease or erase criminal penalties for possession of small amounts.

Only Alaska now permits people to grow their own grass, said George Farnham, the young lawyer who serves as a political director of NORMAL. In most states, growing marijuana is a far more serious crime than getting caught with an ounce or less. Many state laws treat cultivation of even a single marijuana plant with the same severity as selling drugs, imposing mandatory prison sentences.

Farnhan says U.S. grass growers "benefit the U.S. economy by keeping the money in the country instead of giving it to Columbia. It helps our balance of payments."

Buying marijuana from a "hippie farmer in Arkansas" is better than getting it from a multinational smuggling ring, he argues.

Government efforts to halt foreign marijuana production and smuggling, especially the spraying of the poison paraquat on marijuana fields, lead pot smokers to start growing their own, the NORML lawyer suggested.

Fear of paraquat and the Mexican government's success in curtailing marijuana cultivation have cut imports of the Mexican variety sharply, the DEA says. From 2,200 tons in 1978, Mexico's supply to the U.S. fell to at most 1,500 tons in 1979.

Imports of Jamaican "ganga" doubled, however, as troubles in the economy of that island nation lead more Jamaicans to turn to growing and smuggling. Colombia remains the main supplier, exporting an estimated 10,100 tons of marijuana to the United States in 1979. Smuggling has grown to such an organized level that twice in 1979 U.S. drug agents intercepted shipments of 50 tons of marijuana -- an entire shipload.

Marijuana weed, also known as the hemp plant, was cultivated for rope in midwestern states during World War II and still grows wild in much of the country. But marijuana smokers learned long ago that wild weeds don't have the desired impact. The plants are very low in cannabis resin and in tetrahydrocannabinol (Thc), the ingredient that makes users "high."

"People used to look down their noses at homegrown," Farnham says, "but now when you're talking homegrown, you're talking about the best marijuana in the world."

American marijuana is considered more desirable, he explained, because growers have learned how to increase the THC content and grow a crop many times more potent than the imported variety.

The most potent California marijuana contains as much as 6 percent pure THC, agreed DEA agent Schickedanz, while ordinary grass has as little as 0.05 percent of the psychoactive chemical.

To make their stuff stronger, pot farmers plant a different variety. The marijuana grown in Mexico, Colombia and Jamaica and the wild weed in the United States is a plant called cannabis satavia. Another variety grows in Asia, cannabis indicia, containing much more resin.

Americans in Vietnam developed a taste for the Eastern variety and brought the seeds home with them.

But the secret of sinsemilla is in the growing. The cultivators emasculate their marijuana patches, culling out the male plants as soon as their sex can be determined.

Struggling futiley to reproduce without males, the frustrated females pour all their energy into producing THC, because the sticky chemical helps trap pollen.

The result is a monster marijuana plant -- 10 to 20 feet tall, vivid green, bushy as a Christmas tree and literally dripping with THC.

DEA officials estimate that each sinsemilla plant will yield an average of a pound of pot, and some will produce two or even three pounds. Both DEA and NORML representatives agree that $1,000 a pound is the going price for sinsemilla in that quantity.The smoker who buys an ounce will probably pay $100 to $200 for it, pushing the value of a pound to $2,000 or $3,000.

Government drug officials in the past have been accused of inflating the value of drugs to exaggerate their danger. But DEA estimates of sinsemilla output are based on the one-pound-to-the-plant, $1,000-a-pound rule, and NORML officials say the government numbers are, if anything, on the low side.

But the pro- and antimarijuana forces disagree on other aspects of marijuana growing. The people who want to legalize pot describe a cottage industry right out of "The Greening of America" with friendly folks who, as Farnham puts it, "grow a little grass for themselves and their friends."

DEA talks of marijuana millionaires, pot plantations and staggering profits.

A single sensimilla plant will yield 1,500 hand-rolled joints of marijuana too potent for most smokers to consume by themselves. "One plant is enough to keep somebody stoned out of their mind for a year," said Schickedanz.

Each plant requires a plot about three feet in diameter, so a moderate-sized garden will produce 100 plants yielding $100,000 worth of sinsemilla, the DEA agent noted. The biggest grower busted by the DEA in its California raids had 7,200 plants, worth at least $7 million.

With a crop that valuable, the growers don't just throw their seeds in the ground and wait for the harvest, Schickendanz said. About this time of year they start the seeds in individual planting pots, just like tomatoes or cabbages. In the spring, the seedlings are transplanted outside. (Urban growers often produce pot in a closet, using fancy lighting systems that produce the wavelengths the plants prefer.)

Deer, rabbits and other garden pests love the leafy marijuana plants, so most of the serious growers fence their plots with chicken wire or woven wire fencing. To keep out burrowing creatures, they extend the wire underground, and to keep out poachers, more than a few plots have burglar alarms.

Schickedanz said one of the California growers his group caught last year had installed two above-ground swimming pools to hold water and liquid fertilizer for his marijuana garden. "He'd hooked up a couple of pumps. All he had to do was step out of his cabin and hit a switch, the first pump would run until the plants got their water, then shut off automatically. Then a second pump would give them the fertilizer."

The DEA agent estimates "Operation Sinsemilla" wiped out 20 percent to 40 percent of the marijuana crop in northern California last year. But, he admitted reluctantly, "I personally don't think we'll ever stop it."