The American Vanguard Corp. unit that makes...

The American Vanguard Corp. unit that makes the insecticide Phosdrin has bought from Du Pont the right to market the chemical, one of the targets of a fast by farm worker organizer Cesar Chavez. Terms of the deal with Wilmington, Del.-based Du Pont were not disclosed. The deal was conducted by American Vanguard’s unit, Amvac Chemical Corp. of Los Angeles, which has been making the chemical for about three years. Phosdrin, or mevinphos, is one of five chemicals that United Farm Workers union leader Chavez seeks to have banned as a hazard to field workers. Industry and farmers’ groups say the chemicals are safe.