Bean (Phaseolus vulgaris L.) belongs to the legume family (Fabaceae). These include bush beans, common beans, dry beans, dwarf beans, field beans, French beans, garden beans, green beans, haricot beans, kidney beans, pole beans, snap beans or string beans. Beans are considered a warm-season crop, sensitive to temperature extremes. Low temperatures slow down plant growth while high temperatures accelerate it. Most types of bean require a frost-free growing season of 85 to 120 days.
Common bean grows well at temperatures ranging from 15 to 27° C and will withstand temperatures up to 29.5° C. High temperature (close to or higher than 35° C) and moisture stress during flower and pod setting results in abortion of large numbers of blossoms and developing pods. The ideal growing conditions are rainfall of 350–500 mm rainfall during the growing season combined with low relative humidity to minimize risk of bacterial and fungal disease.
In general, beans require deep, fertile soil, from loose to slightly compact, with good physical properties, a pH of 5.5–6.5, and flat or rolling topography with good drainage.
Before planting, a semi-deep tilling should be done (25 – 30 cm), with which the manure is wrapped. If the soil is in the process of disinfection, it is to be tilled again but shallower than the previous one, once the required time elapses. It follows the application of basal dressing and two skim ploughing (15 cm) with harrow or field cultivator. In case of surface irrigation, corresponding ditches and ridges should be done.
In sanded crops, after cleaning the previous harvest, the surface of the sanded ground should be leveled. Then, basal dressing is applied.
Planting & Disease Management
Common bean responds well to both chemical and organic fertilizer. Do a soil test to determine soil fertility status. Apply fertilizer at the time of sowing at a rate of 50 kg per acre and mix 1 kg of humipower per 50 kg for uniform growth, reduce soil acidity and improve water holding capacity.
Ensure the land is weed free by applying Catapult® 480SL 480SL to clear all weeds. The most critical time is between 15–30 days after emergence of seedlings. Use recommended herbicides, Bentagran®Top 240EC 50 ml/20l. After flowering, avoid weeding, or keep to a minimum, as it tends to result in flower loss.
Solution use Bentagran®Top 240EC 50 ml/20L
If irrigation is carried out under rainfed conditions, provide supplementary irrigation during drought periods. Where a sprinkler system is used, avoid overwatering during flowering to lessen flower drop. Use furrows for flood irrigation and water once a week for 2 hours, more often during flowering.
Bean rust (Uromyces fabae)
The disease is characterised by numerous reddish-brown pustules on the leaves. It is more serious on spring beans and all varieties are susceptible. Most damage occurs if infection begins during flowering and pod set. Fungicides such as tebuconazole, cyproconazole, azoxystrobin, metconazole and boscalid + pyraclostrobin may improve yield in either winter or spring beans, but treatment is unlikely to be worthwhile if infection begins when pod fill is complete and the crop is beginning to senesce.
Damping-off Rhizoctonia solani
The pathogens attack any stage of crop beginning from seed rot; damping off of seedlings; or stunting, yellowing and death of older plants. Visible symptoms are the appearance of elongated sunken reddish-brown lesions on roots and stems at or below the soil line. Further the lesions girdle the stem, causing the death of the plant. Older plants may show little indication of the disease, although yields may be reduced. The pith may turn brick- red if invaded by the fungus.
Solution: Use Trinity Gold® 452WP 40 g/20L
Alternaria leaf spot Alternaria alternata
Small irregular brown lesions on leaves which expand and turn gray-brown or dark brown with concentric zones; older areas of lesions may dry out and drop from leaves causing shot hole; lesions coalesce to form large necrotic patches
Solution: Spray with Absolute® 375SC 10 ml/20l
Anthracnose Colletotrichum lindemuthianum (Glomerella lindemuthiana)
Small, dark brown to black lesions on cotyledons; oval or eye-shaped lesions on stems which turn sunken and brown with purple to red margins; stems may break if cankers weaken stem; pods drying and shrinking above areas of visible symptoms; reddish brown spots on pods which become circular and sunken with rust colored margin.
Halo blight Pseudomonas savastanoi pv. phaseolicola
Small water-soaked spots on underside of leaves which turn necrotic and become visible on upper surface; lesions may develop an area of chlorotic tissue around the spots; lesions on expanding leaves may cause distorted leaves; red-brown lesions may be visible on pods; pod lesions may ooze or may turn tan in color.
Aphids Aphis craccivora
Small soft bodied insects on underside of leaves and/or stems of plant; usually green or yellow in color, but may be pink, brown, red or black depending on species and host plant; if aphid infestation is heavy it may cause leaves to yellow and/or distorted, necrotic spots on leaves and/or stunted shoots; aphids secrete a sticky, sugary substance called honeydew which encourages the growth of sooty mold on the plants.
Cutworms Agrotis spp.
Stems of young transplants or seedlings may be severed at soil line; if infection occurs later, irregular holes are eaten into the surface of fruits; larvae causing the damage are usually active at night and hide during the day in the soil at the base of the plants or in plant debris of toppled plant; larvae may exhibit a variety of patterns and coloration but will usually curl up into a C-shape when disturbed.
Solution: Drench Pentagon® 50EC 20 ml/20L
N/B Ensure soil are moist and spray late in the evening or early morning
Spider mites Tetranychus urticae
Leaves stippled with yellow; leaves may appear bronzed; webbing covering leaves; mites may be visible as tiny moving dots on the webs or underside of leaves, best viewed using a hand lens; usually not spotted until there are visible symptoms on the plant; leaves turn yellow and may drop from plant.
Root-Knot nematode (Melaidogyne incognita,M.javanica
They cause stunting and yellowing of plants with a tendency to wilt in hot weather. If infested plants are pulled out from the soil, the roots can be seen to be distorted, swollen and bearing knots of various sizes. Infested roots under severe infestation decay.
These knots should not be confused with legume nodules, which are normally small and round, and are attached to the outside of the roots, whereas swellings of root-knot nematodes are within the body of the root. When active nodules are sliced, they are pinkish in colour.
Solution: Mix 2 kg of adventure with fertilizer during planting or top dressing or drench Alonze® 50EC 10 ml/20l
Bean fly (Ophiomyia spp)
The adult is a tiny (about 2mm long) fly, shiny black-bluish in colour. The female fly pierces the young leaves to lay eggs and sucks the exuding sap. This leaves yellow blotches on the leaves, which are the first signs of bean fly attack and may serve as early symptom useful for monitoring the presence of this pest in the field. Maggots mine their way from the leaves down to the base of the stem, where they complete their development.
Maggot feeding destroys the tissue causing the stem to swell and split and reducing formation of lateral roots. Attacked plants produce adventitious roots in compensation. Maggots (yellow in colour) and pupae (brown or black in colour) can often be seen through the stem splits. Young seedlings and plants under stress wilt and die when attacked by bean flies. Older or vigorous plants may tolerate bean fly attack, but their growth will be stunted and their yield reduced. Damage is more severe in plants growing under poor conditions such as infertile soils and drought.
Solution : Drench Kingcode Elite® 50EC 10 ml/20l