Monsanto Co. (MON) said Thursday that full-year earnings would be at the low end of its existing guidance while its forecast for fiscal 2010 fell well short of analysts' expectations.

The world's largest seed company by revenue is continuing to be hurt by weakening sales of its Roundup herbicide amid tough competition and a drop in global farm incomes.

Monsanto said ongoing earnings per share for fiscal 2009 would be "at the low end" of its previously-announced range of $4.40 to $4.50, with lower-than-anticipated earnings from herbicides outweighing "slightly" higher gross profit from seeds and traits.

The company issued the guidance in a statement ahead of a conference presentation from chief financial officer Carl Casale in London.

The U.S. company's first indication for fiscal 2010 - with ongoing EPS forecast at $3.10 to $3.30 - compared with the $4.10 consensus among analysts.

However, Monsanto retained its pledge to double gross profit by 2012 from a 2007 base as it rolls out new genetically-modified corn and soybean seeds.

Casale warned in a statement that tough competition from generic herbicides created "multiple headwinds" in its goal of securing $1 billion gross profit from the segment by 2012. Profits from Roundup and its other herbicides are forecast at $650 million to $750 million in fiscal 2010.

Monsanto also said it was boosting a restructuring reserve to a range of $550 million to $600 million as part of cost-cutting efforts that will see it trim 8% from its workforce. It aims to cut $220 million to $250 million from annual expenses, realizing a third of this in fiscal 2010 and the full target from 2011.

-By Doug Cameron, Dow Jones Newswires; 312 750 4135;

doug.cameron@dowjones.com