About 75% of processed food -- such as margarine and chicken soup -- on the country's grocery shelves contains engineered ingredients. These include soybeans that have been genetically modified to be more resistant to pests and weeds.

It was the lowly soybean that was the first staple crop to be successfully engineered and widely planted, thanks to Monsanto.

In an effort to bolster sales of its herbicide glyphosate, or Roundup, Monsanto turned to its laboratories to create crops that would tolerate the weed-killer. Instead of trying to alter soy's genes, they layered on new ones.

As a result, the Roundup Ready soybean seed and its patented traits were born and hit the market in 1996. Sales skyrocketed.

So did a new business model, in which farmers aren't buying a 50-pound bag of seeds but paying for a license of Monsanto's biotechnology patents and the right to use those patents for one production year. The price tag can also include additional costs, such as a technology fee.

Now, with the patent on the Roundup Ready soybean expiring in 2014, along with the company's ability to draw royalties, Monsanto is pushing farmers to switch to its second generation of Roundup Ready seeds.

Farmers such as Leake say they have little choice but to go along.

Eoin Treacy's view Monsanto is a global heavyweight in the agriculture sector but talk of antitrust suits, patents expiring and the decline in grain and bean prices appears to be weighing on the share's performance. It has been an underperformer since finding at least medium-term support from October 2008 and has been ranging mostly between $66 and $90 since. The break of the progression of rising reaction lows from October precipitated a lengthier period of base formation extension. The share has exhibited a downward bias since January and while it is now testing the October low, an upward dynamic is needed to suggest this area offers anything other than a temporary area of support. A sustained move back above $75 would be required to break the short-term downtrend and increase the likelihood of a more sustained rally.

DuPont is performing more or less in line with the S&P500. It ranged above its 200-day moving average from August and successfully broke upwards three-weeks ago. While the share is somewhat overextended in the very short-term, a sustained move back below the MA would be required to question scope for further medium-term upside.

Syngenta has sustained a progression of rising reaction lows since bottoming in October 2008 and a sustained move below CHF260 would be required to question the consistency of the medium-term uptrend.

KWS Saat AG has been trading mostly above the 200-day moving average since June and is currently testing the upper side of the range. A downward dynamic would be required to delay potential for a successful upside break.

These additional charts of seed and agricultural chemical shares indicate that Monsanto's underperformance is not common to the whole sector. Laggards usually lag for a reason and Monsanto has to find support in the relatively near future if base formation is not to take place at somewhat lower levels.