Foliage beetles damage on French beans (c) A.M. Varela, icipe
Foliage beetle feeding (here on water melon leaf), the adult is 4-7 mm long (c) A.M. Varela, icipe
In East Africa foliage beetles (Ootheca spp.; Monolepta spp.) are commonly found feeding on bean leaves. Foliage beetles chew small round holes in the leaves. They are about 4-7mm long. They may be a serious problem when present in large numbers or when attacking young plants. Heavy attacks may cause defoliation. Attack on young plants may reduce plant vigour, plant size and yield. The problem is more acute in fields with continuous growing of beans.
Ootheca beetles are normally not serious pest of French beans, but are an important pest of common beans in East Africa. The larvae (grubs) of foliage beetles live in the soil feeding on roots. Their feeding may cause stunted growth and premature ageing of the plants.
Grubs of weevils live in the soil feeding on roots or may bore into the stem of the bean plant causing swellings or galls, as is the case of the striped bean weevil. Plants attacked by grubs of this weevil show stunted growth and may die. The stem of the plant breaks easily during harvesting (see more below).What to do:
Practice post harvest tillage to expose the grubs in the soil to the sun heat and to predators.
Rotate beans with non-host plants such as maize or sunflower to break the development cycle of the pest.
Delay sowing, where practicable, to allow the crop to escape from high populations.
Apply neem; it has been shown to reduce flea beetle numbers and damage
Bean fly(Ophiomyia spp.) on french beans. (c) A. M. Varela, icipe
Bean fly maggot(Ophiomyia spp.) in a french bean stem. (c) A.M. Varela, icipe
Bean flies also called bean stem maggots are serious pests in Africa. 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.
What to do:
Plant early in the season. Bean fly numbers tend to be low during the early stages of the growing season and increase with time.
Provide favourable growing conditions to improve plant vigour and to enhance tolerance to insect attack and damage. For instance, soil fertility can be improved by adding organic fertilisers and well decomposed farmyard manure.
Mulch (e.g. with straw and cut grasses) helps conserve moisture, promote adventitious root development and enhances tolerance to maggot damage.
Avoid planting beans near cowpea, soybean and many other leguminous crops, that may be the source of bean flies.
Remove and destroy crop residues and all plant parts with symptoms of damage by bean flies.
Earth up (building up) the soil around the plants to cover the roots at 2-3 weeks after emergence helps the adventitious roots to grow more quickly. If there is enough moisture, the plants are able to recover from the damage.
Use botanical insecticides such as neem. It has been shown that frequent foliar application with neem extract gives satisfactory control of this pest.
Use resistant varieties: Several lines of dry beans have been identified as having good levels of
Pesticide Resistance is the ability of a life form to develop a tolerance to a pesticide. Pests (weeds, insects, mites, diseases, etc.) that become resistant to a pesticide will not be affected by the pesticide. When pests are resistant, it is more difficult to control the pest. Therefore, it is important to try to prevent pesticide resistance to bean flies in East Africa. These lines are available form the CIAT Regional Programme and from national agricultural research programmes in the region.
Close-up of damage to beans, attributed to Mexican bean weevil, (Zabrotes subfasciatus) (c) CIAT
Bruchids such as the bean bruchid or dry bean weevil (Acanthoscelides obtectus), and the Mexican bean weevil (Zabrotes subfasciatus) are storage pests, attacking dried beans in Africa. They are small beetles (3-5 mm) grey, brown to reddish-brown in colour. Females of the dry bean weevil lay eggs glued to the bean seeds, while females of the Mexican bean weevil lay eggs scattered between the bean seeds. Development takes place inside the bean and takes about one month before the adult emerges. The larvae feed on the seeds destroying them or reducing germination capacity. The adult emerges from the seeds leaving small round holes on the bean seeds. Heavy infestation can result in a large number of holed seeds, with adults moving across the stored beans. The dry bean weevil can attack pods in the field laying eggs on ripening pods. The Mexican bean weevil attacks only beans in storage.
What to do:
Bruchids can be controlled through good storage hygiene. Remove infested residues from last season’s harvest.
When small lots of beans are stored, daily turning of the storage container can significantly reduce infestation.
Complete control of bruchids can be achieved by coating stored seeds with vegetable oil such as cotton seed or coconut oil (small or medium amounts of grain).
Farmer experience: Solar drying of bean seeds before storage is essential. Before storage, treat or mix stored seed with a mixture of plant parts (e.g. neem, lantana, pyrethrum and others), vegetable oil (e.g. neem, coconut, castor bean, cottonseed, groundnut, maize, among others) or mineral substances (e.g. sand, diatomite among others). Diatomite is commercially available as Kensil Lagging from most hardware shops in Kenya.
Pyrethrum (botanical) is effective in controlling weevils.
African bollworm(Helicoverpa armigera) on beans. Caterpillars are 3 to 4 cm in length. (c) A.M. Varela, icipe
Several caterpillars are important pests as pod borers in common beans and French beans. The most common are the African bollworm (Helicoverpa armigera) and the legume pod borer (Maruca testulalis). They feed on leaves, flowers, pods and seeds. The African bollworm caterpillars are 3 to 4 cm long. They make clean circular holes in the pods. One caterpillar may damage several pods. Caterpillars of the legume pod borer attack pods at the point of contact with other pods, leaves or the stem. They frequently web together flowers, pods and leaves with excrements.
Pod borers usually do not cause significant yield reduction in beans. However, they are quarantine pests, and are particularly important in French beans grown for export. If only 1 caterpillar is found in a consignment sent to Europe, the whole consignment may be rejected. If pod borers are found in a field, the beans harvested should be sorted very thoroughly to remove the bollworms manually.What to do:
Monitor the crop regularly
Handpick and destroy infested pods and pod borers. This helps when their numbers are low and in small fields.
Spray crop with biological pesticides (e.g. Bt products or neem).
If pod borers are found in a French beans field, sort harvested pods very thoroughly and remove pod borers manually.
Maize Pest
African bollworm feeding on peas. Fully grown caterpillars are 3-4 cm long. (c) A.M. Varela, icipe
African bollworm (Helicoverpa armigera)
Caterpillars of the African bollworm also known as the corn worm or earworm attack mainly the developing cobs, although they may occasionally feed in the leaf whorl or on tender tassels. Eggs are laid on the silks. Caterpillars invade the cobs and feed on developing grain. Development of secondary infections is common. Local outbreaks of this pest are sometimes severe.
What to do:
Conserve natural enemies. Parasitic wasps, ants and predatory bugs are important in natural control of the African bollworm.
Monitor the crop regularly.
Use bio-pesticides. Plant extracts (e.g. neem, garlic, chilli,) and Bt are reportedly effective against the African bollworms. However, timing of application is very important. Spraying when caterpillars are inside the cob would be ineffective. For more information on Neem click here.For information on Bt click here
Handpick and destroy pod borers. This helps when their numbers are low and in small fields.
Blister beetle(Mylabris oculata) (c) Botha AD (Courtesy of EcoPort)
The adults of the flower beetles, also known as blister beetles, feed on bean flowers (petals and / or pollen) reducing pod set. The adults are medium to large sized beetles (2-5 cm in length), usually black and yellow or black and red in colour. The immature stages (larvae) do not feed on plants. They live in the soil and eat grasshopper eggs.
What to do:
Hand-pick and destroy adult beetles to keep the numbers in check. However, care should be taken, since when disturbed, blister beetles can release a liquid that burn the skin. Whenever possible wear gloves to protect the hands
Do not destroy the larvae, as they are beneficial (they feed on grasshopper eggs)
Bean seed fly(Delia platura) damage on French beans (c) A.M. Varela, icipe
The bean seed fly, also known as seed corn maggot, resembles small houseflies. It is about 1cm long.
Female flies are attracted to recently disturbed open soil, where they lay eggs, especially where there are plant residues or when large amount of manure has been applied. The maggots bore into germinating bean seeds or the cotyledons (first seed leaves) of the young plant eating them. This causes patchy emergence of seedlings. If damaged plants emerge, they are stunted, weak and fail to develop into productive plants.
Pupation takes place in the soil, 2-4 cm under the soil surface.
What to do:
Limit the amount of organic matter before planting in areas with a known history of bean seed flies.
Avoid sowing into recently ploughed land in areas where this fly is a problem.
Flowers and leaves of common bean (c) Arnoldo Mondadori Editore SpA. Courtesy of Ecoport
1. GEOGRAPHICAL DISTRIBUTION IN AFRICA
Geographical Distribution of Beans in Africa . Updated on 8 July 2019. Source FAOSTAT.
2. GENERAL INFORMATION AND AGRONOMIC ASPECTS
Many names are used for Phaseolus vulgaris. 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.
However, presently, two distinct bean types are recognised in the region: French beans (green beans) and common beans (dry beans). French beans are the immature green pods of P. vulgaris and are primarily grown for export market to European Union and elite local urban markets. Common beans are the second most important staple food to maize for the local people.
Beans were introduced to Africa from Latin America several centuries ago. To date beans are a vital staple in Africa, providing the main source of protein. Common beans are mainly grown by women for subsistence and for the local market. French beans (green/snap beans) are grown as a cash crop by large scale and smallholder farmers. They are a major export vegetable commodity in Eastern Africa. The main producing countries in the region are Kenya, Tanzania, Uganda, and more recently Rwanda. In Kenya, most of the crop is grown by smallholders and virtually all is exported to Europe. Estimates indicate that up to 50,000 smallholder families are involved in French bean production in Kenya.
The growth habit of common beans varies from determinate dwarf or bush types to indeterminate climbing or pole cultivars. Bush beans are the most predominant types grown in Africa. However, improved climbing beans introduced to Rwanda in the 80’s have since spread to other countries in the region. They are particularly grown in areas with limited land and high human population.
Climatic conditions, soil and water management
Common beans grow within a range of temperatures of 17.5-27degC. Above 30degC flower buds are likely to fall and seeds are rarely formed at temperatures over 35degC. They are sensitive to night frost. Common beans are usually grown at altitudes between 600 – 1950 m in many tropical areas.
A moderate well-distributed rainfall is required (300-400 mm per crop cycle) but dry weather during harvest is essential. Drought or waterlogging are harmful. Climbing cultivars will give economic yields in areas of high rainfall but the dwarf types appear to be more sensitive to high soil moisture levels. Suitable soil types range from light to moderately heavy and to peaty soils with near-neutral pH and good drainage. Common bean is susceptible to salinity.
The optimum temperature range for growing French beans is 20-25degC, but can be grown in temperatures ranging between 14 and 32degC. Extreme temperatures result in poor flower development and poor pod set. However, French beans mature faster in warmer areas. French beans can be grown between 1000 and 2100 metres above sea level. Rainfed cultivation is possible in areas with well distributed, medium to high annual rainfall (900-1200 mm) but to maintain a continuous production especially during the dry season, irrigation is essential. During the dry season up to 50 mm of water per week is required. This could be applied through furrow or overhead irrigation. French beans grow best on well drained, silty loams to heavy clay soils high in organic matter with pH 5.5-6.5.
Propagation and planting
Normal propagation is by seed but for special purposes stem cuttings can be rooted easily. French beans, grown for fresh consumption, canning or freezing should be planted at 2-3 week intervals in order to harvest all year round, but main export season for fresh beans is October to May. Hence planting for export at 2-3 week intervals should start mid-August and cease end February. Single rows of 30 x 15 cm (1 seed per planting hole) or double rows 60 x 30 x 10 cm are used. For single rows it is advisable to plant in blocks of 4 single rows separated by a path of 50 cm for ease of management. Seed rate is 50-60 kg per hectare.
For good pest and disease management avoid planting French beans too close. A spacing of not less than 30 x 15 cm between the rows and within the row is recommended in Kenya. New plantings should be sited up-wind where continuous bean cropping is practiced. Plant maize, cereals or sunflower between French bean fields to minimise the spread of wind-borne diseases such as bean rust.
Plant population densities are 150,000 – 200,000 plants/ha for dwarf cultivars and half that for climbing types in sole cropping. In intercropping, densities are much lower. For climbing beans, 4-6 seeds are usually sown together in hills spaced 1 m apart. They may also be sown in rows at a spacing of 90-120 x 15-30 cm. Depth of sowing is 3-6 cm. Seed rate depends on seed size and intended plant population densities, up to 120 kg/ha for dwarf beans and 60 kg/ha for climbers in sole cropping. Climbing cultivars require support by stakes or trellis up to 2.5 m in height unless they are intercropped with tall plants such as maize or sorghum – an increasingly common practice in Kenya Rift Valley – the maize or sorghum plants acting as stakes for the bean plants. Avoid planting beans near cowpea, soybean and many other leguminous crops, that may be the source of bean flies.
Husbandry
Beans are comparatively light feeders and require as a guide line about 25-35 kg P/ ha (equivalent to 1-2 bags of Mijingu rock phosphate/ha) and 75-80 kg K/ha. Like all legumes, beans are able to fix nitrogen from the atmosphere, so do not require nitrogen fertilisation. However a soil conducive to nitrogen fixing with the natural nitrogen fixing bacteria present is preferable. Hard soils with little organic matter will not give good yields of beans, unless organic matter is provided, preferably in the form of good quality compost or well decomposed farmyard manure. For pure stands of beans it is preferable to construct slightly raised beds of maximum 1 metre width in order to limit soil compaction around the bean plants. Application of good compost in the beds will improve yields as it will improve nitrogen fixation. Timely and thorough weeding is essential for French beans.
The first weeding should be done 2-3 weeks after emergence followed by a second weeding 2-3 weeks later. During weeding slight ridging of plants will help bean plants withstand attack of bean flies. Cultivating beans when the soil is wet encourages spread of soil-borne diseases such as anthracnose and fusarium root rot. Shallow tillage is preferred especially in the period before flowering as damage to the roots or the collar of the plant encourages soil borne diseases. Common bean can be rain-fed or irrigated. Irrigation is beneficial in semi-arid regions, with overhead irrigation preferred over flood irrigation. In peasant farming, the crop is seldom manured. Crop rotation is necessary to limit soil borne diseases such as root-knot nematodes and fusarium root rot.Fertilise the soil properly and plant French beans on hills or ridges where root rot could be a problem. Avoid furrow irrigation in areas prone to root rot and root-knot nematodes and fusarium.
Mulching
Mulching with straw and cut grasses helps conserve moisture, promote adventitious root development and enhances tolerance to bean fly maggot damage.
Intercropping
Beans are excellent for intercropping with other food crops, such as maize, potatoes, celery, cucumber and can help supply the other crops with nitrogen to a limited degree. Longer season varieties of beans can fix higher amounts of nitrogen than short season varieties. Intercropping with chives or garlic helps repel aphids (KIOF – personal communication).
Water management
A regular water supply is essential for French beans as moisture affects yields, uniformity and quality. Water stress during flowering reduces yields, as does waterlogging. Irrigation in dry spells is recommended as 35 mm per week at planting and 10 days post emergence, followed by 50 mm per week thereafter till end of production.
Pest and disease prevention with EM or BM
EM (Effective Microorganisms) and BM (Beneficial Microorganisms) have been shown to prevent many diseases and a few pests in various crops when sprayed on a regular basis. These are commercial products and are readily available in Kenya. It is organically acceptable and quite cheap.
Harvesting / Storage
French beans are harvested before the pods are fully-grown. Harvest starts 7-8 weeks after sowing in early cultivars. Pods should be picked every 2-3 days, and the number of pickings is greater in climbing than in bushy cultivars. Dry beans are harvested as soon as a considerable proportion of the pods (roughly 80%) are fully mature and have turned yellow. Some cultivars tend to shatter. Usually entire plants are pulled and further dried till ready for threshing. After threshing the beans are further sun dried to estimated 12 % moisture to avoid storage problems.
Farmer practices:
Solar drying of bean seeds before storage is essential. Also before storing, mix bean seeds with a) ashes or ash/chilli mixture b) diatomite (commercially available as Kensil Lagging from most hardware shops in Kenya) c) store completely dry seeds in a sealed container such as a metal or plastic bucket with air tight lid, checking regularly that no weevils are developing and closing tightly again.
Apart from Newcastle which other disease kill chicken most in Africa?
iCow Smart Farmer, Daniel, Kericho
Dear Daniel,
There are many infectious diseases that affect and cause death in chicken like; Gumboro, Newcastle, Fowl pox, Fowl typhoid, Chronic respiratory disease, Infectious bronchitis, Aspergillosis, Coccidiosis, Marek’s disease, among others. To prevent these diseases observe strict sanitation, hygiene and keep a clean environment. Preventive vaccination against some of these epidemic diseases is the most successful control method. Young chicks at 1 day old are given Marek’s vaccine, given subcutaneously, and is done at commercial hatcheries. Other vaccines are; Gumboro vaccine @ 10 days of age and @ 18 days, given in drinking water. Newcastle vaccine given @21 days, 8weeks, and 18weeks, and 3 months thereafter, and is given in drinking water or via eye drops. Fowl pox vaccine given @3weeks and 6 weeks of age, and is given by wing jab. Fowl typhoid vaccine @ 8 weeks of age and is given by intramuscular injection. Please follow the recommended chicken vaccination program. Dial *285# for more on chicken vaccination. Please tell friends and farmers to dial *285# to register and join iCow. Visit iCow menu for much more by dialing *285# including registering your livestock with us under No. 4 Precision farming.
Please advise me on hand spraying of cattle to control ticks.
iCow Smart Farmer, William, Elgeyo Marakwet
Dear William,
Ticks transmit tick borne diseases, e.g. East Coast Fever – E.C.F. Anaplasmosis, Heart water, Babesiosis also called Redwater, cause irritation and damage of hides. Tick control is very important and is done by using right acaricides, and in correct concentration. This may be done by dipping in cattle dips or by spraying. There are;
1. Amitraz basedacaricides, e.g. Triatix, Taktic, Tix-Fix and Norotraz.
2. Synthetic pyrethroids based products, e.g. Ectomin, Decatix, Dominex, Vectocid, Grenade and Delete.
It is advisable to spray or dip your cattle at least once a week, and when the tick challenge is high, e.g. at the start of rainy season, it can be done twice a week. If hand-spaying, restrain the cow properly, to thorough soaking use 15 – 20litres of the wash per cow. Successful control of ticks using this method depends on; proper animal restrain, accurate measurement and mixing of the acaricide, use of an efficient pump, thorough application of the wash on all parts of the cow’s skin. The cow should be sprayed from the rear end working towards the head; starting with the hind legs, inside and outside, then, the udder, under the tail, the tail itself, belly, flanks, backline, front legs, shoulders, neck and the head, ending with the inside of the ears, and always spraying in an upward direction.
The cow could be suffering from a disease called Bovine babesiosis; common name is Redwater, after the dark red-coloured urine, as you have observed in your cow. The disease is transmitted by ticks and is caused by a parasite called babesia. This disease is curable. Please call a vet doctor to examine and treat the cow. The disease can be prevented by effective control of ticks by use of acaricides through proper dipping or hand spraying. Please see in the next SMS on how to improve on your hand spraying. Please tell friends and farmers to dial *285# to register and join iCow. Visit iCow menu by dialing *285# for much more including registering your livestock with us under No. 4 Precision farming. You can also send the word TICK by SMS to 20285. Thank you. Keep up your good work.
