Vegetables











Phaseolus vulgaris var. humilis
Snap Bean or Bush Bean

Disease:

Bacterial and wilt diseases are common among the Bean family. This plant disease arrives with summer heat and humidity. This often occurs just before, or during, the ripening of the crop. Rhizoctonia and Pythium cause young bean seedlings to wilt and collapse or damp-off from water-soaked rotting of the stem near the soil line. With Pythium, the stem has a more watery rot that is colorless to dark brown. The slimy outer tissue of the stem slips easily from the central core. With Rhizoctonia, the stem initially appears water-soaked, but may dry and turn brown or form reddish-brown to brick red, slightly sunken cankers on the stem.Fungicides are recommended in areas of high heat and humidity.

Rust (Uromyces phaseoli var. typical) attacks all above ground parts of the bean plant, but is most commonly seen on the underside of the leaves. The rust fungus is not seed-borne, but it overwinters on old bean plants. Spores produced on old bean plants are spread to new bean foliage by the wind. Early symptoms of the disease may be seen approximately five days after spores land on the leaves. A new crop of spores is produced about every 10 days. The first symptoms of rust on the foliage are very small, white, slightly raised spots or pimples, which may be surrounded by a yellow halo. The white pimples later become raised, reddish-brown pustules. These rupture and release a powdery mass of spores (seed-like bodies), which give a rust, color to the fingers if rubbed across an infected leaf.

Anthracnose, caused by the fungus Colletotrichum lindemuthianum, is favored by cool, wet weather. It may cease to be active during hot, dry weather. This fungus overwinters inside bean seed and diseased bean plants left in the field after harvest. This fungus can live in the seed as long as they remain viable. Fungus spores will survive in old bean debris under field conditions for more than two years. Once the disease is brought into a field on the seed, people and equipment can spread it by splashing rain and insects, or when the beans are wet. The disease may show up on the leaves, stems or pods of bean plants. Dark brown to black, oval-shaped cankers with purple borders often occur on the bean stems and leaf veins. However, the most easily recognized symptom of anthracnose occurs on the pods as small, rust to reddish colored spots. This is the first evidence of the disease. These spots enlarge, turn dark brown to black and sink into the pods. A brownish, sometimes slightly raised border develops around each sunken spot, whose center may be covered with pinkish ooze during wet weather.

Note: At webinfotech.tzo.com/Gardening101 we do not use fungicides as we believe in natural ways to control such problems.


Insects and Pests:

Most varieties of beans are susceptible to a variety of insects, most notably beetles. The cornstalk borer, attack seedlings. Important foliar pests include lepidopteran larvae (e.g., corn earworm) and beetles (e.g., Mexican bean beetle). Whiteflies are also a serious pest for fall beans. Stinkbugs and corn earworm are the more important pests attacking the pods.

Other arthropods that attack snap beans include aphids, European corn borer, thrips, cucumber beetle, weevils, tarnished plant bug, vegetable leafminer, potato leafhoppers two-spotted mites, and seed corn maggot. Any of these insects can cause substantial damage to snap beans if conditions favor insect populations They can be effectively treated with Sevin, Diazinon or a variety of other insecticides.

Bunnies love beans! Rabbits eat the the tender new leaves. If there are rabbits in your area, a rabbit fence is not a nicety, it is a necessity. They will devastate a row of beans in a hurry, eating the tender new leaves. As new ones develop, they will come back for more.

Note: At webinfotech.tzo.com/Gardening101 we do not use insecticides or pestacides. We believe wholly in pest and insect control through natural means.