Proper selection of planting materials

Common beans come in a tremendous variety; the pods can be green, yellow, purplish brown or striped and the seed colour varies from white to brown or black, red, striped, mottled or multicoloured. The main varieties for dry beans are Calima, Reds, Navy Bean, Cream Coloured, Brown and Yellow Coloured, Purple Beans, Medium Whites, Large Whites and Blacks.

The large number of varieties makes it difficult to decide which varieties to grow. Some of the varieties are indigenous while others are improved and each has its own traits. It is, therefore, necessary that a farmer identify a selected number of varieties that have been observed to be superior with respect to certain traits under local production conditions.

Choice of suitable varieties

The choice of the right variety depends on the market requirements, local growing conditions and the availability and quality of seeds.

To determine which types and varieties of beans are locally grown, ask the farmers the following questions:

Which types of beans are commonly grown in the area, green or dry beans?
Are there any new varieties that have been promoted in the area?
How are the new varieties performing under local conditions?
What do you consider when choosing bean varieties to plant?

a. Market requirements

Multipurpose varieties: Varieties grown primarily for self-sufficiency are those that can be eaten as fresh green beans, fresh or dried seeds, and sometimes also the leaves. Multipurpose varieties are usually climbing beans or runner beans that can be harvested over a longer period of time.
Green beans: In densely populated areas and those near towns, the demand for fresh green beans is high. Farmers can grow fresh green beans for the market. Such farmers are, however, advised to test any green bean varieties on a small plot before scaling up since most green varieties are very sensitive to growing conditions.
Dry beans: Dried shelled beans can easily be stored. They, therefore, provide an important food in the off-season period and can be sold in off-season and distant markets.

b. Location

Beans grow in temperate and warm climates alike. Very high temperatures though cause shedding of the flowers and malformed beans. On the other hand, drought reduces the cropping period and the yield.
Before growing a new variety, it is necessary to verify where the variety comes from. Varieties growing on high altitudes may not grow well in low altitudes; varieties from arid areas may not grow well in humid areas. It is advisable to make tests on a small plot before scaling up production.
Some varieties are better resistant to drought and are, therefore, more suitable for arid locations.

c. Seed availability and quality

Use of healthy seeds is important to ensure good development of the crop. Healthy seeds can be bought from trustworthy commercial suppliers that can guarantee virus and disease free seeds. If own seeds are used, they should be selected carefully in order to avoid spreading seed-borne diseases like bean mosaic viruses. When choosing a variety, in addition to its yield potential under local conditions, special attention must be given to resistance or tolerance to prevalent pests and diseases. Several tolerant bean varieties have been adopted by farmers and released in some countries.

Varieties	Country	Remarks
MAC 13, MAC 34, MAC 64	Kenya	Climbing beans
Ndundu, Manseki, Mpolo	D.R.Congo	Climbing beans
Sepe, Mbidi	D.R.Congo	Bush beans
Moore 88002	Burundi	Bush beans for low elevation and high humidity areas
Lyamungu 90	Tanzania	Bush beans for low elevation and high humidity areas
RWR 719	Rwanda	Resistant to common foliar diseases and root rots
MLB-49-89A, MLB-39-89A	D.R.Congo	Resistant to common foliar diseases and root rots
SCAM -80-CM/5	Burundi	Resistant to common foliar diseases and root rots
Beshbesh, Melkie	Ethiopia	Resistant to Bean stem maggot (bean fly)
RWR 2075, RWR 1946	Uganda	Resistant to root rot and tolerant to low soil fertility
RWR 1783, Calima type	D.R.Congo	Tolerant to soil acidity and low phosphorus
STTT165-92(Chore), RAB484 (Dinkesh), XAN310(MelkaDima), G843(Alemaya),STTT-165-96 (Chercher)	Ethiopia	Improved varieties

Recommendations to farmers regarding seed selection:

The following process can be done better as a group of farmers rather than an individual in order to identify the most suitable bean varieties for the given location:

Collect all bean varieties in the area. These can be identified by the skin colour or growth characteristics.
Separate seeds according to the identified varieties.
Let each farmer take the same amount of one preferred variety and plant them at a selected experimental plot in the garden. Make sure that no other beans are planted within 100 metres of the experimental plot.
All farmers should plant in the same season and manage the plots in a similar way. Proper monitoring during the growing period is important.
Record all experiences with the variety (e.g. time to maturity, yield, pest and disease observations).
Repeat the experiment for another season in different plots in order to confirm the results.
Select the best varieties and discard the worst ones. Ensure that seed of different varieties are continuously separated in the field and in storage.
Store selected seeds well; the beans should be well-formed without any signs of infection. Dry them to a good moisture level (hard but brittle when bitten) and mix with dried leaves of neem, marigold or any other botanical to keep off storage pests.

Treatment of seeds against infections

The use of chemical seed dressing is prohibited in organic agriculture. In order to prevent contamination of the seed with pathogens, seeds for propagation must only be taken from healthy plants and dried under optimal conditions. Bright sunlight has a certain disinfecting effect. Therefore, beans must be turned regularly during drying to benefit from the sunlight. Optimal germination conditions help the young plants overcome early infestations.