Activist investor Nelson Peltz’s Trian Fund Management LP, which holds a $1.6 billion stake in DuPont , called on the chemical conglomerate to separate its high-growth agriculture and other businesses from units that generate strong cash flows. DuPont should split itself into two companies, one holding the company’s agriculture, nutrition and health and industrial biosciences divisions, Trian Fund said in a Sept. 16 letter to DuPont’s board released on Wednesday. DuPont has also announced a $5 billion share repurchase program.