Billy Carter said yesterday he will buy the controlling interest that his brother, President Carter, now holds in "Carter Warehouse Inc.," the family's peanut warehouse business.

The President's brother, who runs the business, told reporters in Plains, Ga., that he doesn't know what he will have to pay for the President's roughly 62 per cent interest. "We havent made a deal yet, but we're working on it," he said.

The warehouse, one of several Carter family financial holdings that taken together are valued at about $5 million has a declared value of about $1.8 million. But last August, Billy Carter estimated its replacement value at $3.5 million.

The President's mother, 78-year-old Mis Lillian, is the only other owner of the warehouse, and is expected to keep her share of the holdings.

An appraisal is being made, Billy Carter said, under the terms of the trust President Carter signed Jan. 20 authorizing a trustee to manage his holdings for him to avoid conflict of interest.

The trustee is Atlanta lawyer Charles Kirbo, a longtime close personal friend and adviser to Carter.

While the trust gave Kirbo the right to sell, lease, or otherwise manage or dispose of the President's holdings as Kirbo saw fit, it also set out some of Carter's "concerns, which he hopes, but does not direct, that the trustee will recognize . . ."

Carter hopes Kirbo "will be sensitive to the fact that [his] brother, Billy Carter's, livelihood is directly affected by many decisions which the trustee will made," the trust agreements said. It continued:

"The effect of such decisions on Billy Carter, who has been [Carter's] business partner for many years, should be weighed carefully . . ."

The trust agreement, released for the first time Friday by the White House, also spells out Carter's hope that Kirbo can preserve an opportunity for one of the President's sons, "especially James Earl Carter III," to "become a part of those businesses in which the Carter family has been involved for many years" if they want to.

It ends with the statement that Carter "has an affinity for those farm lands which are owned by Carter's Farms, Inc., and he hopes that the purposes of this trust can be accomplished without the trustee's having to sell the farm lands."