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Issue No. 23, Article 8/October 9, 2009

Soybean Harvest Is Underway

Soybean harvest activities will be in full force in the coming weeks as weather permits. NASS reported 6% of soybean acres were harvested as of October 4, which is 34% behind the 5-year average. Soybean development has been a couple of weeks behind the 5-year average all season long, and 2009 will certainly go down as a unique season. Soybean development remained a few days to a week behind 2008 until the end of August, when it slipped two weeks behind 2008 because of cold August temperatures. Interestingly, the development progressed at a seemingly accelerated pace in September, closing the gap to 2008 development as maturity approaches.

These state data are consistent with observations in my research plots, where it seemed that the R3 to R5 stages developed slowly but R5 to R7 developed fast. I know the latest-planted fields still need some more heat and sunshine, but unfortunately in the last week or so we have been back in cooler weather patterns, with temperatures 3 to 8°F below average. Cool, wet weather and crop development behind average have been the story all season long. Nonetheless, harvest is narrowly here, and the question of what this soybean crop can yield is soon to be answered. I hope that the answer is a plentiful and safe harvest for all of you.

Here are some meandering thoughts regarding soybean harvest:

  • Make certain your combine is properly adjusted and in good working condition. The most common loss of yield due to harvest operations is at the cutter bar, so pay particular attention to its adjustments and condition.
  • As you harvest, monitor your loss to make necessary adjustments. This can be simply done by counting the soybeans left on the ground behind the combine. Harvest loss can't be eliminated, but a good goal is to lose no more than 1 bushel per acre, which is 30 to 40 soybean seeds per square yard, depending on seed size. For more information check out "Combine Settings for Minimum Harvest Loss."
  • Combines are also good at spreading problems across fields and to different fields. Make a plan that accounts for reducing movement of weed seeds and/or sclerotia from white mold infection. If you have patches of weeds that were difficult to control, or if you are among the many growers with white mold (Sclerotinia stem rot) this year, combine those patches or those fields last if possible. If you can't harvest them last because of deteriorating crop conditions or logistics, clean out the combine as well as you can before leaving the infested areas and moving to other areas. Both weed seeds and sclerotia from Sclerotinia stem rot can survive in the soil for many years; limiting their spread can help future management challenges. (Sclerotia are the small, hard, irregularly shaped black structures found on the outside or inside of a soybean plant infected with white mold. For more information, see Carl Bradley's previous article in the Bulletin [issue 18, July 24] or the Purdue University Extension publication "White Mold" [Adobe PDF])
  • First, last, and always--think safety!

--Vince M. Davis

Vince Davis

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