ROANOKE -- When U.S. Forest Service officials catch marijuana growers on forest land in Virginia this summer, they hope to be doing more than getting rid of the marijuana.

"We'll destroy the crops and try to make some arrests," said Rudy Caruthers, an administrative officer for Jefferson National Forest.

In the past, the Forest Service was empowered only to rip up the plants found on the 1.6 million acres that make up the Jefferson and Washington national forests in Virginia, Caruthers said. Arresting the offenders was left to state and local police.

But the National Drug Enforcement Act, passed this year, gives Forest Service officials the authority to arrest marijuana growers; 500 forest officials nationwide will be trained as drug agents, Caruthers said recently in an interview from his office here.

Caruthers said he did not know how many officials in Virginia will be trained as drug agents, but some are already undergoing the training.

Last year, about 100 marijuana plants were seized and destroyed on federal forest land in Virginia, Caruthers said. The 1987 crop has just been planted, he said, and officials have taken to the skies to look for fields cleared for cultivation.

In the summer, authorities say, they will bring in more aircraft to step up their aerial surveillance.

Marijuana grows well in the state's forest land, officials with the Roanoke County Extension Service said.

"From what I've heard, it grows here pretty well," horticulture technician Jacqui Parkhill said from her Salem office.

An extension agent in the office, Larry Boitnott, said 1987 could be a good year for marijuana in Virginia if growers planted seeds between the heavy rains that fell this spring and if the seeds did not wash away.