Occasionally, the crop may be ready to harvest but the field, or part of the field, may still be green or weedy. Harvesting when green stems or green weeds are present may result in stained beans. Similarly, weeds with purple berries, such as Eastern black nightshade and American pokeweed, can cause severe staining.
Also, secondary growth of beans can occur as plants begin to mature, particularly when rainfall follows an extended dry period. Where direct harvest is intended, a desiccant can be applied to dry the remaining green tissue.
Harvest aid products are available to burn down weeds and desiccate the crop. For more information see OMAFRA Publication 75, Guide to Weed Control. There may be different application timings for different products, so refer to and follow all product labels. There may also be restrictions on use of certain products for dry edible beans exported to specific markets. Check with the bean dealer on restrictions.
If on-farm storage is necessary, store individual varieties of dry edible beans in separate bins that are free from other grains and oilseeds. Keep harvested beans free of stones, glass and other seed-size contaminants. Failure to maintain the purity of the crop can result in lost value.