Shares of E I DuPont (DD) have been in a slow retreat ever since the company announced third quarter earnings before the New York markets opened for trading on October 26. Not because of anything the company reported, in my opinion, but because in the last week or so we’ve moved into a “sell the news” reaction to just about all good earnings reports.

If that continues for a bit (and I’ll try to define “a bit” at the end of this post), I think you’ll get a chance to pick up the shares of a seed company that is taking advantage of troubles at competitor Monsanto (MON) for a very reasonable price.

For the quarter DuPont reported earnings of 40 cents a share, 6 cents a share above the Wall Street consensus. Revenue grew by 14% from the third quarter of 2009 to $7 billion. Wall Street had projected revenue of $6.76 billion.

And going forward DuPont raised guidance for the full year to $3.10 a share. That’s above the $3.04 Wall Street consensus and the range of $2.90 to $3.05 in the company’s previous guidance.

Not bad results, hey? Well, since then the stock has declined gently from $47.70 on October 25 to $46.20 at 1:30 ET on October 27. I think that’s a reflection of a general weakness in the market in the last few days and of some profit taking in DuPont shares that had climbed to a new 52-week high at $48.

What especially interests me in the shares—beyond the company’s expectations for continued strong demand from global markets in its chemicals business—is the gains in market share reported for its seed business. The company’s seed business Pioneer Hi-Bred increased its corn market share by three percentage points (to 35%) and by five percentage points (to 31%) in the soybean market. Some of that gain comes thanks to disarray at competitor Monsanto, which very aggressively priced its most recent generation of seeds and then saw market push-back from farmers who didn’t see the extra performance in the field that would have justified all of that higher price.

I’m looking here for a slight further pull back to near the 50-day moving average at $44 a share. (That’s my definition of “a bit) I’d be a buyer near that price. The shares currently trade at 13.7 times trailing 12-month earnings per share. That’s below the 14.7 multiple for the Standard & Poor’s 500 and the 5-year average price to earnings ratio of 15.5 for DuPont itself. And, by the way, the shares currently pay a dividend yield of 3.47%