Lettuce Price Rise tettuce Price Rise  
SALINAS, - -Calif. ÛÓ The worldÛªs largest' lettuce producer was struck by'2,600 workers, and within hours wholesale prices went up 50 cents a carton.</br></br>That rise from $3.50 to $4 a carton was expected: to be quickly reflected on market shelves around the country. .</br></br>The Bud Antle Inc. workers, members of Teamsters Union Local 890, walked off the fields after a breakdown in negotiations Thursday. The union is demanding $6.50 an hour. Antle offered $5.85. They were making S5.25 an hour.</br></br>FITCHBURG, Mass.ÛÓA tank hold-ing the highly toxic chemical vinyl chloride exploded last night, injuring at least six people and causing the evacuation of 2,000 residents as a dangerous vapor cloud spread about a mile south of downtown, authorities said.</br></br>All four employes inside the Great American Chemical Co. plant at the time suffered burns and lacerations, Fitchburg fire department officials said.