Ah, the fall harvest.

Sweet Jersey corn. Plump pumpkins.

Northern Lights No. 2?

Yep, there's another crop whose harvest is finishing up this month, but it won't likely - or legally - be found at any of the state's roadside produce stands. Ÿ

It's pot.

And while Garden State stoners might be celebrating the marijuana high season, authorities are salivating to seize their sativa.

At this time every year, police and prosecutors fire up their efforts to both thwart growers and stop the flow of weed across a nation with a $20 billion appetite for bong hits.

"In New Jersey, this is the busiest time of the year," said Detective Sgt. Dennis Donovan, who heads the marijuana unit of the New Jersey State Police. "The last couple of weeks have been very busy."

It's already been a banner year for the Drug Enforcement Agency in New Jersey when it comes to grass seizures.

For fiscal 2005, which ended Sept. 30, agents seized 17,076 pounds of marijuana in the state, a 548 percent increase over 2004, said Michael Pasterchick, who heads the New Jersey DEA.

That's more than the agency seized in 2002, 2003 and 2004 combined.

The battleground will begin to shift soon, as the grow season ends and the first frost nears. From now until next summer, buds cultivated in the Northeast will require sophisticated indoor grow rooms to survive.

The use of indoor marijuana rooms is a growing trend, especially in New Jersey - and one that authorities say has become a chronic problem.

"This is the most densely populated state in the country, and we're running out of outdoor areas to grow," Donovan said. "We're seeing more indoor grows this year than all of last year."

Through the end of September, state police had busted 23 indoor grow rooms, the same as in all of 2004, he said.

From the grow rooms - where pot can be cultivated under ideal conditions throughout the year - the state is seeing much stronger strains of marijuana, Donovan said, bearing names such as Northern Lights.

He calls it "the Starbucks effect," in which people shy away from commercial grades of coffee for much more expensive specialty varieties.

"Nobody wants Maxwell House anymore," Donovan said. "The trend is going to high-quality, high-potency, high-THC. ... Everybody wants hydro weed."

Tetrahydrocannabinol (THC) is the chemical in marijuana that causes its effect. "Hydro" is short for hydroponic, a way to grow marijuana indoors without the need for soil.

New Jersey is clearly more of a buyer than a seller in the pot game. It ranks 46th in terms of pot as a cash crop, growing marijuana with a retail value of around $25 million annually. It's the seventh most valuable crop in the state, ahead of apples, wheat and potatoes, according to data from the National Organization for the Reform of Marijuana Laws (NORML).

"We start early in the season identifying plots," said Pasterchick of the DEA. "We'll then do surveillance on them, see people coming and going, watering and fertilizing. When the plants start to mature, we take them down."

Marijuana reportedly remains the fourth largest cash crop in America. In states such as California, Kentucky and Tennessee, it dwarfs other crops in terms of value. California alone, with its famed Emerald Triangle in Humboldt County, produces more than 1 million pounds of pot every year with a street value in the billions.

In just one raid in August, California authorities seized 742,684 plants with an estimated street value of $2.6 billion from a farm in the northern part of the state.

"There is not a week that goes by that we don't seize hundreds of pounds of marijuana coming into New Jersey," Pasterchick said. "We are an import state. ... We don't go after marijuana smokers, we go after marijuana traffickers."

To Pasterchick and other drug fighters, there is a silver lining in the pot smoke cloud. The use of marijuana is down 18 percent nationally since 2001, he said.

In assessing the pot problem in New Jersey and elsewhere, Pasterchick is blunt.

"Marijuana is a drug that can end you up in the hospital," he said. "This is not just some recreational drug."

Groups such as NORML, of course, have their own views. To them, pot is less dangerous than alcohol and statistics about increased potency are myths fabricated by the DEA to continue an expensive and failed drug war.

The group sponsors marijuana events throughout the country, including one celebrating the crop the first week of October in Madison, Wis., called the Great Midwest Marijuana Harvest Festival, now in its 35th year.

Calls to the New Jersey chapter of NORML were not returned this week.