If hard rains occur, causing the soil to bake before the seeds have germinated, the crust should be broken by the use of a weeder. This tool is also used to some extent after the plants are up. Some of the plants may be destroyed, but this is not objectionable if the stand is very good. The least damage to the plants will be done if the weeder is used in the middle of the day, when the stems and leaves are not so rigid.
Thorough tillage is essential to large yields. The weeds must be controlled and the moisture conserved. As the bean is a shallow-rooted plant, deep tillage should be avoided, for it results in root pruning, which is always detrimental to the bean plant. Implements with a large number of narrow teeth or shovels are best adapted to the cultivation of this crop. In the culture of field and garden types on a large scale, riding cultivators are commonly employed. When the plants are small, shields should be used on the cultivators to prevent covering them. The culture should be level until the last cultivation, when wings should be used to throw up a slight ridge for the support of the plants.
There is an almost universal agreement among practical growers and plant pathologists that this crop should never be cultivated when the plants are wet from dew or rain. ,The Cornell Station (Cornell Station Bulletin 255) comments as follows in regard to this matter: "Cultivating or working beans when wet should be avoided as much as possible. On this point there can be no dispute. The character of the parasite causing the disease and the practical experience of the growers everywhere show that this recommendation is correct".