There's nowhere to go but down.

Monsanto (NYSE:MON) knew that revenue from its herbicide, Roundup, would peak this year. Unfortunately, it peaked a little lower than expected.

The agriculture giant said that it expects to hit the low end of its earnings guidance this fiscal year because it'll only bring in $2 billion in gross profit from Roundup and other glyphosate products compared to the $2.4 billion it previously expected.

The lower revenue appears to be mostly due to strong competition from Syngenta (NYSE:SYT), Dow Chemical (NYSE:DOW), and Chinese generics, which has forced Monsanto to lower the price of its Roundup. That's good news for fertilizer producers like PotashCorp (NYSE:POT), Mosaic (NYSE:MOS), and Agrium (NYSE:AGU), because it means the lower sales aren't entirely due to external factors that are causing farmers to plant less acreage.

Higher sales of seeds should make up for some of the missing profit, but hitting $4.40 in earnings this year is still a disappointment -- especially for a company that seems to be constantly raising guidance.

While the short-term outlook for Monsanto might not look as rosy, the long-term future of Monsanto was never based on Roundup. As long as the company can continue to develop seeds that increase yields, and consequently profit for farmers, they'll be able to increase revenue and earnings. It's the seeds -- not the chemicals -- that are the future of Monsanto, and seed sales are headed in the right direction.

Trading at over 30 times expected free cash flow for this fiscal year, Monsanto certainly doesn't look insanely cheap. But high-growth companies hardly ever do.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.