The slide in Monsanto shares, which have fallen by more than 40%, gained fresh legs on Wednesday despite the group pledging a return to "mid-teens" earnings growth, driven by renewed growth in profits from seed.

The seeds and sprays giant revealed that in the US, where it has attracted farmer criticism for the prices of its cutting edge biotech seeds, it would "offer more products at more price points" in corn, its biggest seller.

The group also flagged as a "key driver" corn seed sales in South America, notably Argentina and Brazil, where it is preparing for a greater take up of genetically modified crops.

Monsanto would in its 2011 financial year, which starts in September, report a "double digit" rise, equivalent to at least $460m, in gross profits from seeds, after a smaller rise, of some $100m-200m, expected in the current year.

Shares slip 

The group was "well positioned to meet our objective for mid-teens earnings growth, driven by our seeds and traits business", Hugh Grant, the Monsanto chairman and chief executive, said.

However, the statement failed to impress analysts, who have already forecast a rise of some 20% in Monsanto's earnings next year, to more than $1.6bn.

Monsanto shares slid 4% to $45.30 in morning deals in New York, their lowest since November 2006, before recovering some ground to close at $46.22, down 2.4% on the day.

The stock topped $140 two years ago at the height of the boom in farm commodities.

March of GM slows

The group's forecasts came as it reported a 45% slump to $384m in earnings for the March-to-May period.

The decline was lead by the continued decline in takings from its Roundup herbicide brand, for which Monsanto has abandoned attempts to maintain as a premium product in the face of steep competition from generic competition.

The Roundup business recorded a loss of $189m for the quarter, from a gross profit of $273m a year before.

However, the seed division also reported a lower gross profit, down 1.5% to $1.41bn, as sales stagnated in the key corn and soybean markets.

Separately, the US Department of Agriculture noted a slowdown in the march of genetically modified corn into the American market, with its share of sowings rising by 1 percentage point this spring to 86%.

The advanced, so-called stacked, varieties, which combine a number of different biotech traits, "were planted on 47% of the acreage, up 1% from a year ago".