In the wake of the most widespread forest fires in 20 years, state forestry officials are concerned about the Reagan administration's efforts to abolish a grant program that helps train firefighters so that they can work across state lines.

Since 1972, the U.S. Forest Service has provided matching funds to states to cover half the cost of training their firefighting crews to meet national training standards.

If a state's firefighters have not received the required training, they cannot be sent to help another state if a large fire breaks out. Thus, the state foresters say, the federal funds give states with lower standards of training an incentive to provide more.

Since the Reagan administration took office, however, it has tried to abolish the training grants. So far it hasn't succeeded, but funding has declined over the past five years.

In 1980, the Forest Service provided $20 million in grants to the states and spent $2.7 million on technical assistance for them. Since then, the grants have dropped to about $10 million a year.

For fiscal 1986, the administration again wants to abolish the grants, but it would provide $3.2 million in technical help.

Florida state forester John Bethea said, however, that without the grants "the program for all practical purposes will be dead."

Bethea said the current level of $10 million "is the bare minimum for training and maintaining a national system." State foresters, he said, "would not have the funding to develop training programs."

But Lawrence Amicarella of the U.S. Forest Service said the federal government provides the states with little money for firefighting anyway; state funds, he said, account for at least 90 percent. The administration, he said, prefers to provide technical assistance rather than share in the training costs.

The grant program is an outgrowth of federal efforts that began in 1911 because of concern that states and private landowners were not being as careful with their land as they should be. The federal government decided that the states and individuals needed incentives to manage land properly and develop the capability to fight wildfires.

This year, the fires have been particularly severe. As of last week, 75,062 wildfires, covering more than 2.1 million acres, had been reported to the Forest Service's Boise Interagency Fire Center.

"No state would want to maintain a crew large enough to fight this year's fires," said Melinda Cohen, speaking for the National Association of State Foresters. "Everything has to be standardized nationally." States do pick up the cost when other states' firefighters travel to help them.

This year, for example, the Minnesota division of forestry sent as many as 120 firefighters outside the state. South Carolina's state forester, Leonard Kilian, said that in June alone his state loaned a 20-man crew to Montana and supervisory personnel to Nevada.

As of Monday, the Boise Interagency Fire Center had coordinated the transfer of 3,100 firefighters from eastern states to fight fires out West this year.

"What the administration expects the states to do is make up for that money . . . ," said Bruce Miles, state forester for Texas and president of the state foresters' group. "The states have not been able to do that." Miles said that all Texas state agencies have already been forced to absorb cuts of between 5 and 10 percent because of revenue losses related to declining oil industry profits.

In the past, Congress has agreed to provide at least some funds for the firefighting program. The House appropriations bill for the Interior Department, which includes the Forest Service, would keep the grants at their current level. The Senate will take up its bill later.

"We have lost $1.5 million in the state budget this year . . . . We have firefighters on loan out West that have received layoff notices," said Jim Brooks, assistant director of the Minnesota Division of Forestry. "It is not every year that we get a very serious fire season, so it is easy to forget" about the program, Brooks said. "And people want a tax cut."