Country star Willie Nelson has canceled his Memorial Day concert at the Merriweather Post Pavilion due to an injury suffered to his left hand earlier in the week. A new date is expected to be announced in a few days, according to Post Pavilion representatives.

Meanwhile, 78,000 tickets at $20 apiece went on sale yesterday for Nelson's 4th of July "Farm Aid II" at the University of Texas Memorial Stadium. Though no lineup has been announced, Nelson has said that he's invited all participants from the first Farm Aid to repeat their performances. The noon-to-midnight concert will be broadcast live on VH-1, the adult cable channel companion to MTV.

Tickets for the July 6 RFK Stadium concert featuring Bob Dylan, the Grateful Dead and Tom Petty and the Heartbreakers will go on sale Friday at 10 a.m. at the RFK Stadium box office, the box offices at the Capital Centre, the Baltimore Civic Center and the Patriot Center, Maryland Waterbeds and all TicketCenter locations. There is a limit of six tickets per customer; tickets will cost $20, cash only, at these locations. Telephone orders can also be made at 385-0044 or (800) 468-3540.

The concert will begin at 2 p.m., rain or shine. A limited number of general admission tickets will be sold for the field. All other seats are reserved in the stands.