Beans

Beans (Phaseolus vulgaris) are originally from the central and South America. Through the increment of processing vegetable, beans obtain their importance as fresh vegetable world wide. The category Phaseolus L. comprises more than 200 species however, the most commercially used are the P. vulgaris L. ssp. vulgaris var. nanus (bush bean) and P. vulgaris L. ssp. vulgaris var. vulgaris (runner beans).

There are different colors (yellow, blue, violet and green) and sizes (5 to 25 cm) of pods. Also, there are different seed colors; white, light brown, brown and white-red.

Beans have a weak main root with many secondary roots.

On the lateral roots, the root-tubers are formed with the nitrogen fixing bacteria Rhyzobium leguminosarum, which lives in symbiosis with the bean plant.

3.1.1. Ecological Requirements

Soil

Beans can growth in many different soils; however, the less ideal soils for beans are those with high content of sand or clay and with very low pH. The optimal pH lies between 6 and 7.5.

Temperature Requirements

Beans require soil temperatures of at least 8-10 °C for germination and at least 12°C air temperature. Furthermore, strong winds can damage leaves and flowers resulting with yield reduction.

3.1.2. Planting Systems and Soil Management

Suitable Cultivars

The amount of varieties of beans (both, bush and runner beans) is very diverse. A selection of the beans can be carried out according to the end purpose. (green and yellow for the

Banana in intercropping with beans.

fresh market and processing industry.) The selections of the varieties can be classified from the development period (to plan for the processing industry), pod size, type of production and resistance to diseases. Varieties for the processing industry should be specially selected for the harvest with machines, considering resistance and the ability of said varieties to ripen homogeneously while demonstrating good sensorial characteristics and global characteristics of consistency and flavor.

Propagation and Field Preparation

Organic beans are propagated by seeds sown directly into the fields.

The seed bed should be middle fine, and demonstrate few crop residues on the soil surface. A good seed bed is an important condition for an homogeneous emergence that improves after the mechanical weed control.

Design of Plantation

In organic systems in the tropics and subtropics, beans can be found in two different cropping systems, the rotational cropping and intercropping system. Depending on the cropping system, there are different cultural practices:

Organic Beans under Rotational Cropping System

Plant Density

There is a close relationship between the plant density and yield. In the tropics and subtropics, there is a high variation of plant density, distance between the rows etc. depending on the tools and machinery that are available in each region.

Generally, beans will be seeded with 40-50 cm distance of row and 4-5 cm depth. Depending of the end use, variety and local conditions, optimal plant density is 25 to 50 plants per m². Beans for the processing industry may be sown between 30 to 40 plants per m²for the fresh market and those harvested by hand several times may be sown with 25 to 32 plants per m².

The start of the crop is important for the success of bean production. Beans need the best possible seeding and emergence conditions. Seeding by wet soils, for example, can cause the growth of beans to completely fail.

Crop Rotation

The productions of beans should have an interval period of 3 to 4 years if they are grown by themselves. Cereals as oat, wheat and maize, are convenience preceding crops for beans. However, crop harvesting with heavy machines must be avoided, especially during soil wet conditions.

Crops that are not convenient for beans are potatoes, and cruciferae.

Bean plant (P. Vulgaris)

Beans leave light – available nitrogen in the soil.

Therefore, it is important to seed a cover crop (grass mixture) or a crop after the harvest in order to fix the nitrogen in the vegetative parts of the plants (especially in high rainy areas).

It is also recommendable to use minimum tillage to avoid high mineralization of the organic matter. As following crops, species with a high nitrogen demand such as lettuce, fennel, broccoli, spinach or cauliflower are recommendable. Cereals and arable crops can be also used as following crops to beans.

Fertilization

A general nutrient requirements for beans is 30 kg of nitrogen per ha, 20 kg of phosphor per ha and 70 kg of potassium per ha.

In normal active and organically managed soils, the requirements of the beans may be covered without addi- tional organic fertilizers, especially if green manure (grass mixture) was incorporated before bean seeding. If the soils have low nutrient content, compost or animal manure (up to 15 t/ha) should be applied 2 weeks before seeding. It is important to avoid utilizing too much organic fertilizer (animal manure, compost etc.), as a high supply of nutrients makes beans more susceptible to disease.

Organic Beans under Intercropping System

One of the most traditional methods to grow beans (runner beans) in an intercropping system is the maize-beans- zucchini cropping method. However, in this traditional system, crop rotation is not implemented and generally a repetition of the intercropping is carried out year after year.

However, in some regions a one year fallow is utilized. One of the bases of organic agriculture is balanced crop rotation.

Therefore, adequate crop rotation has to be planned. For example; Maize-beans-zucchini // vegetables // leguminous as crop // cereals // green manure.

Maize and beans are mostly sown together during the main rainy period. Because in a maize-beans-zucchini intercropping the harvest of the product occurs separately

and the agricultural implementations are carried out with animals, the row distance is of about 80 cm for beans. The plant density may be of 50 plants of maize per m², and 30 plants per m². Zucchini is mostly planted by distributing some seeds over the entire field according the needs of the farmer. It is important to mention that sowing is done manual- ly, and the depositions of the seed into the soil occurs in the following traditional way: 3 seeds of maize and two of beans are seeded in every 50 cm hole. After emergence, one maize plant is removed from the each hole, and one or two bean plants are left. The fertilization in the maize-beans-inter- cropping can be directed from the maize plant require- ments. However, little experience with organic fertilizers exists. A possible recommendation for such intercropping systems can be the following: a base organic fertilization some weeks before sowing with 15 tons of cattle dung and applications of compost to the maize plants in the following maize stages: between 4 to 6 leaf stage of the maize, a hand full of compost; at the beginning of silk emergence of maize and at full flowering, also a hand full compost. One possible improvement of this method is using bush beans and planting the maize from beans separately, but in the same line.

Irrigation

In areas with warm and dry periods, it is recommendable to irrigate the beans during and after the flowering.

Different types of beans: Vicia faba, Phaseolus vulgaris, Vigna angularis.

3.1.3 Pest and Disease Management

Diseases

Through appropriate crop management, especially crop rotation and organic fertilizations, diseases are generally not a problem. However, a number of diseases can appear:

Pest Management for Beans

Table 48:

Disease of Beans and organic control Managment

Disease Important to Know Preventive Measures Direct Measures

Halo blight (Pseudomonas It is one of the most important bacterial bean Use of healthy seeds and resistant varieties. The first In the case of a high potential for infection, it is feasible syringae pv. phaseolicola) diseases. Wet and warm periods increase the infection herd must be removed from the field. to spray low dosages of cupper (be care full, leaves

infestation possibilities. This disease is propagated can be burn).

mostly by the infected seed.

Antracnose (Colletotrichum This fungi cause one of the most important mycosis Preventive measures: use of healthy seeds and lindemuthianum) infections. Cool and wet temperatures foster the resistant varieties. Apply in four year intervals in the

propagation of the fungi. crop rotation as the disease appears.

Sclerotina and Botrytis Avoid wet soils, high plant densities, and over

fertilization with nitrogen. If there is a problem with Sclerotina, a three year interval with cereals and Liliaceae must be implemented.

Mosaic virus This virus causes changes in the bean leaves with tolerant varieties, virus free seeds, living barriers mosaic forms, eventually, the infected part of the such as maize and oat to reduce the dissemination plant dies. This can cause high yield losses. of aphids.

The dissemination of the virus is via aphids, mechanically, and through the seed.

Table 49:

Pests of Beans and Organic Control Managment

Pests Important to know Preventive measures Direct measures

Black Aphids (Aphis fabae) Due to dangers psed by infestation, field monitoring

must be carried out and remove the infestations nest from the crop. Natural enemies must be promoted by leaving a high diversity of vegetation at the edges of the fields.

Direct measures: eventually an application with lube soap, or pyrethrum and rotenone.

Bean fly (Phorbia platura, syn. Do Not use the following crops as preceding crop; Until now do not exit a direct control.

Delia platura and D. florigale) namely, cruciferae, spinach and potatoes.

No applications of fresh cattle manure to the crops.

3.1.4 Weed Management

Adequate weed regulation is an important base upon which to build good yields. Early and extended weed competition during bean development can dramatically reduce the pod yield, while late competition with a middle weed density may influence the yield. Therefore, it is important to have a weed free period, between the first 4 to 6 weeks.

A Pre-weed regulation before bean sowing of can save much work during the growing season. Pre-weed regula- tions consist on tillage the soil (minimum tillage or plough) just before the sowing of the following crop. Weeds that have emerged are then incorporated into the soil. Therefore, it is important to wait at least two weeks after the cover crop for the seedbed preparation.

Weeds on crop beans can be blind controlled between the seeding and the emergence stage, with a light pressure on the soil of a comb-harrow. The comb-harrow work can only be successful until the 2nd and 3rd leaf stage of the weeds; therefore, such implements must be employed as early as possible.

One or two passes with the comb-harrow by the first 5 to 6 weeks of bean development can regulate weeds.

The advantage of the comb-harrow is that it covers the surface widely.

In the case that the comb-harrow can not be used, because of wet soils or possible damage to the bean plants, a hoeing implement can be applied. The hoe weeding implement can control larger weeds, and generally two or three passes are more than sufficient. Weeds that are between the plants can be controlled manually.

Weeds that can produce seeds during the bean crop- ping period can affect the harvest through to seed weed contamination, e.g. amaranth.

3.1.5 Harvesting and Post Harvest Handling

The harvest period can be determined through the dry matter content of the pod. (at the beginning of the harvest, 7-8%, and by the end 9-10%. As a rule the brake method can also be used, which consists in breaking the pods (cracks when is broken); the broken points should be green and juicy, and the seeds (depend the variety) no longer than 8-10 mm.

For the fresh market, the pods can be washed and assorted.

Beans can be packaged in bags or cartons and stored at 5 to 7 °C, maintaining a shelf life of 6 to 10 days. The pods should be ties inside of the bag.

Fields of beans in Peru.