Ellen Kullman, Chair of the Board and Chief Executive Officer of DuPont attends a session at the annual meeting of the World Economic Forum (WEF) in Davos January 23, 2014. REUTERS/Ruben Sprich (Reuters) - DuPont

said on Monday Chief Executive Ellen Kullman is to retire this month and will be replaced temporarily by board member and veteran U.S. executive Edward Breen, who oversaw the break-up of conglomerate Tyco International.

The chemical and crop company cut its earnings forecast for the second time this year, citing the strong U.S. dollar and further weakening of agricultural markets, primarily in Brazil.

Shares of DuPont, officially known as E.I. du Pont de Nemours & Co, rose 4.9 percent to $53.79 in extended trading.

Kullman, who joined the company more than 27 years ago, has been its CEO since 2009. She acknowledged as recently as last week that the price of its shares, which are down 27 percent so far this year, was "a concern."

Under Kullman, DuPont fended off an attempt by activist investor Nelson Peltz's Trian Fund Management to land board seats earlier this year. Trian declined comment on Kullman's exit.

Because of the tough currency and demand environment, DuPont lowered its 2015 forecast for operating earnings per share to about $2.75 from $3.10. It already cut its forecast in July.

Excluding the impact of currency, operating earnings per share for the year, including expected benefits from share repurchases and cost savings, are expected to rise 3 percent from a year earlier.

Kullman is set to leave Oct. 16, when Breen will take over as interim CEO.

(Reporting by Sneha Banerjee in Bengaluru and Christian Plumb in New York, writing by Bill Rigby; editing by Maju Samuel, Bernard Orr)