Rust (Uromyces appendiculatus)
Is favoured by high humid conditions. It causes slightly raised, small white spots on the lower leaf and these spots turn red to dark brown. It can be managed and control by crop rotation and spraying sprays such as Baycor 30% EC, Anvil, Alto 100SL, Dithane M45 etc after every two weeks is highly effective. It can also be controlled by dusting sulphur at 25 kg/ha.
Angular Leaf Spot (Phaeoisariopsis griseola)
Causes brown or red coloured spots with purple edges and grey to brown centres on the leaves, stalks and pods. This disease may cause the leaves to fall of pre maturely. It can be curbed by treating the seeds with chemicals like Fernasan D at 3gm per kg of seed. The disease can also be checked by spraying chemicals like Benomyl.
Harvesting and Yield
French beans can be harvested in pod stage as well as can be harvested for its seeds. The pods are harvested in immature and tender stage, which are ready for harvest within 7 – 12 days after flowering. But harvest also depends totally on type of varieties. In bush varieties, 2 or 3 harvests are made and in case of pole type variety, 3 to 5 harvest are made. If the french bean are harvested for seeds, it is to be ensured that pods are harvested only after maturation. They should be harvested ideally before the seeds bulge out of the pod. The beans should be picked after morning dew is completely off and the pod is dry. Harvesting can be done manually or through machine but hand harvest is better. It should be carefully removed, so that the pods are not damaged. Harvested pods should be allowed to dry little under sun before packaging them. Make sure the pods are not squeezed. The yield greatly varies from types of cultivars, with 8 to 10 t/ha in bush varieties and 12 – 15t/ha in case of pole type french beans. It gives an yield of 1250 to 1500 kg/ha seeds.
It is a major protein source and thus has greater demand across the world. The farmers enter into marketing strategy by encouraging contract farming, which involves price setting. They are grown by the farmers in large areas covering several hectares, which are brought to market for large scale selling via various middlemen and other traders. With a little more strategic marketing, it can be widely exported from India to various countries and also can be marketed on a large scale in India.