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Dry bean planting varying according to regional conditions. In Michigan, planting takes place between late‐May and early‐July, with about 75% planted in the first two weeks of June. Dry beans that do get planted in cold, wet soils typically struggle throughout the growing season fending off root diseases. In order to improve conditions at harvest time, growers “roll” bean fields between planting and emergence with a wide roller to flatten the field surface. This process presses any stones and rocks below the soil surface and flattens the surface, which enhances cutter bar efficiency and results in significant reduction stones, dirt balls and debris in the harvested beans (J. Cramer 2020, personal communication).

Fig. 4.1. Unit operations in raw dry bean handling and cleaning.

Dry bean seed is usually treated with a combination of insecticides to prevent loss due to insect pressures. These products are very effective but have a relatively short life. Growers utilize several methods to control weeds, which compete for moisture and nutrients. Most common is a pre‐plant application followed by a post‐emergence application if needed. Herbicide resistant weeds are becoming a greater challenge (Sprague and Everman 2017; Soltani et al. 2018). As the dry bean plant grows, the canopy covers the field and vulnerability to mold proliferation begins during the flowering stage. White mold (Sclerotinia spp.) is the single biggest yield‐limiting factor in in dry beans in USA. Typically, fungicide is applied between the first flowers and earliest pod formation depending on field history and conditions. In certain circumstances, a second and occasionally a third application may be advantageous (Schwartz et al. 2011).

Most dry beans reach maturity in about 100 days, moisture content decreases as plants mature. Dry beans will store long term at moisture levels ≤18%. Maintaining good quality becomes more difficult when mechanically harvesting dry beans at the lower moisture levels. While the moisture level of the seed may be appropriate for harvest, often, the plant’s vegetative structures remain green, which complicates the harvest process, thereby compromising quality. To alleviate this detrimental condition, growers will often apply plant desiccants as harvest aids. Harvest aids kill the plant and significantly reduce plant moisture, and they improve the harvest process and overall seed quality (Knodel et al. 2019). Harvest aids work excellent in early September when daily temperatures are still warm, but efficacy declines when temperatures are cooler, and skies are more overcast during October (S. Bales 2021, personal communication). When harvest aids are used, strict preharvest intervals (PHI) between application and actual harvest are mandatory.

Early dry bean harvest is associated with maximum yields and complimentary to successful winter wheat planting. Dramatic changes in harvest technology have taken place from traditional “pull, windrow, thrash” to “direct harvest combining” (Eckert et al. 2011). Traditionally, this process has served the industry well over the years. The development of upright dry bean plant structure has led to direct harvest, allowing growers to spread the high cost of a combine over their wheat and soybean acreage and eliminating the need for pulling and windrowing equipment (Zyla et al. 2002). It is estimated that as much as 80% of the dry bean acreage in Michigan is direct harvested.

Both conventional combines with rasp‐bar cylinders and rotary‐cylinder combines can work well for dry beans when properly equipped and adjusted for harvest conditions (Kandel and Enders 2019). Care is taken to operate cylinder speeds as slow as possible to help limit bean splits and checking. Often time cylinder speed also needs to be reduced as the day progresses in order to compensate for additional drying that takes place in the late afternoon (ADM 2017). Additional measures that help maintain bean quality when direct harvesting is to keep the combine cylinder near maximum capacity without overloading. This can be accomplished by adjustments in ground speed of the combine or harvest width. By keeping cylinders near maximum capacity, a cushioning effect is created by the plant reside as beans pass through the threshing mechanism (Kandel and Enders 2019).

Growers take extra care by flushing and cleaning their harvesting equipment when switching classes between fields (Bingen and Siyengo 2002). Buyers specify limits to mixed classes of beans based on quality although not injurious to health. Cross‐contamination with soybeans presents a significant allergen risk and is cause for load rejection at the elevator. Growers are diligent to maintain a barrier between fields and quite often use dedicated combines if they have both crops on their farm operation. Extra care is also taken to make adjustments within their respective harvests processes to minimize damage to the actual seed coat of the bean. The lower the percentage of cracked or checked seed coat the greater the quality because the bean maintains its integrity when canned. The higher the percentage of seed coats that have been fractured, the poorer the beans’ function when canned or cooked (J. Cramer 2020, personal communication).

Growers are paid for their beans on a cleaned, dry weight. Upon delivery at the elevator/processing facility, the load will be sampled and graded. Grading includes a visual inspection for safety, testing for moisture, screening for foreign material, and hand sorted to determine what percentage of the load is suitable for consumption. The elevator operator/processor also uses this grading process to determine where the load will be received (Bingen and Siyengo 2002). The lot is managed to assess need for additional mechanical drying, making beans suitable for long term storage.