BUSINESS DIGEST: TUESDAY, APRIL 5, 1988
LEAD: COMPANIES Dart Group has expressed interest in F. W. Woolworth. The disclosure pushed Woolworth's stock up $8.875, to $54.125. Woolworth responded by adopting a ''poison pill,'' giving existing shareholders the right to buy additional shares at half price. The Dart Group in the last three years has bid unsuccessfully for Beatrice, May Department Stores, Jack Eckerd, Safeway, Federated Department Stores, Supermarkets General, Dayton Hudson and Stop and Shop.