Delivery drivers and warehouse workers at Laura Scudder’s distribution centers in Northern California went on strike after negotiations over a new three-year contract collapsed. About 220 workers set up picket lines outside 15 of the snack-food manufacturer’s facilities from Visalia to the Oregon border and from San Francisco to Reno, said Le Roy Salido, secretary-treasurer of Teamsters Local 588 in Hayward. “It won’t be a short strike because of the issues involved,” Salido said. The 2-month-old talks derailed in Pleasanton when management offered a contract that would have taken away union benefits, Salido said. Management’s proposal would have frozen workers’ salaries and pension benefits, instituted a split workweek, and lowered drivers’ commissions on sales by 6%, Salido said. Company officials were unavailable.