Agriculture Reference
In-Depth Information
every conceivable trait: time of ripeness, stringless, use as green bean, use as dry bean, to name but a
few. Other selection criteria:
• plant: adaptation to given local growing conditions (day length, temperature, etc.); time of ripeness
(earliness); healthy, robust foliage that does not wilt; height; resistance to diseases and pests; root
quality (good nodulation)
• pod: quantity, flavor, lack of string, thickness of flesh, tenderness, length and width, number of beans
per pod, size of beans
• seed: true-to-type shape and color
• bush beans: lack of “tendrils,” ease in harvesting, synchronous ripening
• pole beans: development of new pods after picking for increased yield
• usage: for example, in polyculture with corn, not especially vigorous growth that ripens with the corn
DISEASES AND PESTS
Of the diseases that can come up in bean cultivation, several are seed-borne, the
most important being anthracnose, brown spot, and viruses. The bean weevil can also be spread
through sowing infested seed. Bean rust (fungus:
Uromyces appendiculatus
) is not seed-borne. Symp-
toms: in spring white, in summer red pustules on leaves, stalks, and pods. Prevention and treatment:
keep afflicted plants out of the compost pile, disinfect bean stalks.
Anthracnose (fungus:
Colletotrichum lindemuthianum
) mainly affects bush beans. Symptoms:
leaves, stalks, pods, and seeds can be affected. Look for brown spots, with dark or red edges, that are
somewhat sunken into the tissue. Wet weather encourages spreading and heightens the intensity of this
disease. Prevention and treatment: do not use affected seed. Do not grow beans in the same plot for at
least three years, burn affected foliage, or compost well. Brown spot (bacteria:
Pseudomonas syringae
)
is a bacterial disease. Symptoms: “water-soaked” spots on leaves, stalks, and pods that spread. Pole
beans are affected less often. The bacteria can be spread from affected to healthy seed during seed
cleaning. Remedies: do not use affected seed, thinner plots in the field, do not plant in wet areas. Re-
move afflicted plants; do not grow beans in the same plot for at least three years. The black bean aphid
(
Aphis fabae
) can also affect the common bean.
The tender, violet flowers of a pole bean
The most important of the viral diseases affecting the common bean is the bean common mosaic vir-
us (BCMV). Aphids are the most common vector of this disease, though it can also be seed-borne.
