Monsanto has lost its second chief financial officer, and company veteran, in a little over a year with the resignation of Carl Casale to become boss of CHS, the huge farmer-owned co-operative.

Mr Casale, 49, is on December 31 to leave Monsanto after 26 years at the seed and sprays company, where he rose to the top finance job in September last year.

He replaced Terry Crews who retired at the age of 53 after a 32-year career at Monsanto, and held the post of chief financial officer during the last crop price spike, when shares in the group topped $140.

During Mr Casale's 14 months in the post, Monsanto shares have fallen by 28% as it has slashed prices for its Roundup herbicide, amid tough competition from generic alternatives, and faced increased rivalry from DuPont in core US seed markets.

Rising profits 

Hugh Grant said that Monsanto would "miss" Mr Casale, but understood the "strong attraction of the opportunity that awaits at CHS".

Mr Casale, while forecasting Monsanto's future as "very strong", said that being hired as chief executive of Minnesota-based CHS "provides a compelling opportunity".

"I feel privileged and excited to be part of a company owned by farmers and ranchers."

At CHS, he will replace John Johnson, who is retiring after 15 years as head of the co-operative, which sells and processes grains and oilseeds on behalf of its members.

CHS two weeks ago unveiled earnings for the year to the end of August up 32% at $502.2m, on revenues down 2% at $25.3bn.

Monsanto, for the same period, reported earnings down 47% at $1.11bn, on revenues down 10.4% at $10.5bn.

Monsanto shares stood 0.6% higher at $59.82 in afternoon deals in New York.