State police in Maryland and Virginia will begin combing tobacco fields, state parks and even front lawns next month for marijuana, wielding search warrants and shovels to destroy home-grown crops of the illicit weed.

The crackdown, announced yesterday by Maryland State Police, is part of a $1.9 million federally funded effort to eradicate home-grown marijuana across the country. Virginia authorities said that they will implement a similar program, as they have in previous summers.

"We expect a bumper crop," said Lt. Fred Davis of the Maryland State Police narcotics squad. "Little patches should start sprouting by now and, come August, we will be tangled with the stuff."

Last year, law enforcement authorities confiscated 3.7 million pounds of home-grown marijuana nationwide, according to agents of the Drug Enforcement Administration. Some of the illegal weed had a street value of as much as $3,200 a pound, they said.

The National Organization for the Reform of Marijuana Laws (NORML) estimates that up to $100 million of home-grown marijuana is produced every year in Maryland.

The police do not dispute NORML's claim but say that it is impossible to determine exactly how much marijuana is growing in the state.

Whatever the amount, police say they plan to leave no leaf unturned in their attack on the crops. They intend to use drug-sniffing dogs, aerial surveillance and cash rewards to informants.

Once the pot has been spotted, police plan to find and arrest the growers. Then, armed with search warrants and shovels, officers will go into the fields and dig up the plants. The marijuana will be taken to the state health department, where samples will be tagged and photographed for use as evidence and the rest incinerated.

George Farnham, national director of NORML, said he believes that when the federal government sprayed Mexican marijuana fields with the deadly insecticide paraquat some years ago it spurred the planting of more home-grown marijuana in the United States.

But some federal agents assert that the rising price of marijuana on the street--now as high as $250 an ounce for sinsemilla, considered a top grade of marijuana--is the leading reason for the increase in home crops. The home-grown weed, Maryland police said, sells for as low as $15 an ounce.

Last year, Maryland State Police confiscated 502 marijuana plants and arrested 14 growers. Most of the growers, police said, were small-time drug dealers seeking a little extra spending money.

Virginia State Police, in contrast, confiscated 5,000 marijuana plants last year, according to Wayne Garrett, assistant deputy director of the State Police. Investigators there concentrated their efforts on Loudoun, Prince William and several south central counties.

Maryland State Police say that this summer they will concentrate on Frederick, Charles, Queen Anne's, St. Mary's, Calvert and Wicomico counties.

Some marijuana "farmers" have been tilling the soil in state parks to avoid detection by their neighbors, according to Det. Steve White of the Maryland National Capitol Park Police.