Monsanto (NYSE: MON) shareholders know it's been a tough year for the agricultural giant that foodies love to hate. The company's stock is down some 35% year to date following a poor launch of its new SmartStax corn seed and ongoing concerns about growing weed resistance to its flagship Roundup product. Further, the company's declining margins indicate that it's losing its previous pricing power to generics and other competitors.

Monsanto's poor performance, however, is an outlier in a sector that's been benefiting from rising corn and other agricultural commodity prices.

Different strokes for different folks
Seeing growing demand for fertilizer, for example, BHP Billiton (NYSE: BHP) made a hostile bid for fertilizer miner PotashCorp (NYSE: POT), which propelled the latter's stock up nearly 40%. That's sparked a bidding war of sorts for Potash's fertilizer assets and helped push up valuations for industry peers such as Mosaic (NYSE: MOS).

Yet it's been more than just macroeconomic tailwinds and M&A activity helping Monsanto's competitors. Exhibit A: rival Syngenta's (NYSE: SYT) third-quarter sales report. Historically, Syngenta has been strong in crop protection products and in Europe and Latin America and weak in seeds and in North America -- not coincidentally, the opposite areas and business lines where Monsanto is weak and strong, respectively. Yet Syngenta's third-quarter sales numbers showed an interesting new trend: Corn and soybean seed sales were up 22% year over year in the third quarter and total seed sales were up 82% in North America. That compares to corn and soybean seed sales that had been up just 3.6% through the first half of the year and up just 13.8% in North America. Clearly, Monsanto's stumbles with SmartStax benefited Syngenta and helped that company beat analyst expectations.

What it all means
Going forward, it will be interesting to see if Syngenta can hold on to or expand on these gains in seeds and in North America. Should that prove to be the case, then Syngenta is worth more than its current $57 stock price.

Although it will take a few more quarters to see if Syngenta is able to sustain these gains, the lesson for investors is that the old Wall Street adage "There's always a bull market somewhere" is true. If you see one company stumbling, think about who might be benefiting from those struggles. When you figure that out, odds are you'll find an outperformer.

Tim Hanson is advisor of Motley Fool Global Gains. Monsanto is a former Motley Fool Inside Value pick. Syngenta is a Motley Fool Global Gains recommendation. Motley Fool Options has recommended a synthetic long position on Monsanto. Try any of our Foolish newsletter services free for 30 days. True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Motley Fool has a disclosure policy.