Check Combine Settings and Scout Fields Prior to Soybean Harvest 

Shawn P. Conley, Eileen Cullen, and Paul Esker

The word that best describes preliminary soybean yield estimates from across the Midwest is variable.  Whole field averages ranging from 7 to 70 bushels per acre are being reported in southern Illinois and Indiana.  The limiting factor in many of these low-yielding environments has been rainfall.  Growers should take extraordinary precautions this year to check combine settings throughout the harvest day especially if they switch soybean maturity groups.  Much of the rainfall that occurred in the drought areas of WI occurred too late to aid early maturity group soybeans (these soybeans were physiologically mature-R7 growth stage prior to rain); however many late maturity group varieties were still in the R6 (grain-fill) growth stage and may have benefited from the mid-August rainfall.  As growers proceed in harvest a quick in-field estimate can be preformed to assess where yield losses are occurring.  The three areas of concern are pre-harvest loss (standing soybean), header loss (harvested swath in front of combine), and machine loss (harvested swath behind combine).  In each area of interest count the number of beans per 10 ft².  Remember 40 seeds per 10 ft² equal ~1 bushel per acre yield loss.  The reason for this yield loss concern stems from a similar environment that occurred in Northern Indiana in 2005.  In some fields I assessed as much as 7 bushel per acre yield loss due to improper harvest (Image1). 

 Image 1.  Fall volunteer soybean due to improper combine set-up.

¹Image from R.L. Nielsen; Purdue University

 As growers check soybean fields for grain moisture prior to harvest it may also prove prudent to check pods for bean leaf beetle feeding. If little to no feeding is present harvest can be delayed, however if pod injury is significant these fields should be harvest first to limit grain quality concerns (decreased germination and increased fungal presence) (Obopile and Hammond, 2001; Smelser and Pedigo, 1992a; Smelser and Pedigo, 1992b).

 Literature cited:

Obopile, M. and R.B. Hammond. 2001. Effects of delayed harvest on soybean seed quality following bean leaf beetle (Coleoptera: Chrysomelidae) pod injury. J. Kans. Entomol. Soc. 74:40-48.

Smelser, R.B. and L.P. Pedigo. 1992a. Soybean seed yield and quality reduction by bean leaf beetle (Coleoptera: Chrysomelidae) pod injury. J. Econ. Entomol. 85:2399-2403.

Smelser, R.B. and L.P. Pedigo. 1992b. Bean leaf beetle (Coleoptera: Chrysomelidae) herbivory on leaf, stem, and pod components of soybean. J. Econ. Entomol. 85:2408-2412.