African Cassava Mosaic Disease (ACMD).

African cassava mosaic disease is one of the most serious and widespread diseases throughout cassava growing areas in Africa, causing yield reductions of up to 90%. It is spread through infected cuttings and by whiteflies (Bemisia tabaci).

Symptoms occur as characteristic leaf mosaic patterns that affect discrete areas and are determined at an early stage of leaf development. Symptoms vary from leaf to leaf, shoot to shoot and plant to plant, even of the same variety and virus strain in the same locality. Some leaves situated between affected ones may seem normal and give the appearance of recovery.

What to do:
  • Use disease-free cuttings. If it is not possible to find cassava plants that are completely free from the disease, select cuttings from stem branches instead of from the main stem. Stem cuttings from the branches are more likely to sprout into disease-free plants than stem cuttings from the main stems (James et al, 2000).
  • Resistance to ACMD has been successfully incorporated into high yielding cultivars of acceptable quality through breeding programmes at IITA. Use resistant/tolerant varieties (e.g. "SS 4", "TMS 60142", "TMS 30337" and "TMS 30572").
African Cassava Mosaic Disease
© A.A. Seif, icipe

African Ca…

African Ca…

Anthracnose (Glomerella manihotis)

Initial symptoms of the disease are oval lesions ("sores") on young stems. On older stems, raised fibrous lesions develop that eventually become sunken.

What to do:
  • It is not an economically important disease in most cassava growing countries and it does not warrant any intervention.
Anthracnose on cassava stem
© www.iita.org

Birds and other vertebrate pests

Birds, rodents, monkeys, pigs and domestic animals (cattle, goat and sheep) are common vertebrate pests of cassava.

Measures that help to manage damage by these pests include:

What to do:
  • Fence farms and set traps in the fence.
  • Cover exposed roots with soil.
  • Weed your cassava farm to discourage rodents pests.
  • Harvest roots as soon as they are mature (James et al., 2000).
Rat
© Reg Mckenna, wikipedia

Rat

Red-Billed…

Red-Billed…

Goats

Pigs

Brown leaf spot (Cercosporidium henningsii)

Symptoms are restricted to older leaves. Brownish round spots with definite borders appear on the upper leaf surface. On the lower leaf surface, they are brownish-grey in colour. Infected leaves later become yellow and eventually drop. In wet areas the disease may cause a yield reduction of up to 20%.

What to do:
  • Though the disease is widespread in most cassava growing countries, it is not an economically important disease problem and it does not warrant any intervention.
Brown leaf spot
© A.A.Seif, icipe

Cassava bacterial blight (Xanthomonas campestris pv. manihotis)

It is a major constraint to cassava cultivation in Africa. Infected leaves show localised, angular, water-soaked areas. Under severe disease attack heavy defoliation occurs, leaving bare stems, referred to as "candle sticks". Since the disease is systemic, infected stems and roots show brownish discolouration. During periods of high humidity, bacterial exudation (appears as gum) can readily be observed on the lower leaf surfaces of infected leaves and on the petioles and stems. The disease is favoured by wet conditions.
This disease is primarily spread by infected cuttings. It can also be mechanically transmitted by raindrops, use of contaminated farm tools (e.g. knives), chewing insects (e.g. grasshoppers) and movement of man and animals through plantations, especially during or after rain. Yield loss due to the disease may range from 20 to 100% depending on variety, bacterial strain and environmental conditions.

What to do:
  • Use clean planting material. This can reduce disease incidence in areas where cassava bacterial blight is already widespread.
  • In cases of sporadic occurrence of the disease, collect cuttings only from healthy plants and from the most lignified portion of the stem, up to 1 m from the base. Check visually the cuttings for vascular browning. Disinfect tools regularly.
  • Intercrop cassava with maize or melon. This been reported to reduce cassava bacterial blight significantly.
  • Practise crop rotation and fallowing. These practices proved very successful when the new crop was planted with uninfected cuttings. Rotation or fallowing should last at least 1 rainy season.
  • Remove and burn all infected plant debris and weeds. Alternatively plough them into the soil.
Cassava bacterial blight
© Grahame Jackson (Courtesy of EcoPort)

Cassava brown streak virus disease (Potyvirus - Potyviridae)

It is particularly serious in coastal areas of Kenya, Zanzibar, Mozambique and Tanzania and lakeshore region of Malawi and in Uganda and is a threat to the whole of sub-Saharan Africa.
The virus is vectored by whiteflies (Bemisia spp.) and also transmitted through infected cuttings. Symptoms include yellowing (leaf chlorosis) and brown streaks in the stem bark (cortex). Infected tubers have brown streaks (root necrosis) (Field Crops Technical Handbook, MoA, Kenya). It's a stealth virus, which destroys everything in the field. The leaves may appear healthy even when the roots have rotted away.

What to do:
  • Use diseased-free cuttings.
  • Use tolerant/resistant varieties (e.g. "5543/156", "TMS 30572")
  • Remove diseased plants from the field.

The cassava green spider mite (Mononychellus tanajoa or M. progresivus)

This mite is green in colour at a young age turning yellowish as adult. Adult females attain a size of 0.8 mm. They appear as yellowish green specks to the naked eye. They occur on the lower surface of young leaves, green stems and auxiliary buds of cassava. Damage initially appears as yellowish "pinpricks" on the surface of young leaves.

Symptoms vary from a few chlorotic spots to complete chlorosis. These symptoms are somehow similar to African cassava mosaic disease, and should not be confused. Heavily attacked leaves are stunted and become deformed. Severe attacks cause the terminal leaves to die and drop, and the shoot tip looks like a "candle stick". Green spider mites are major pests in dry season. Severe mite attack results in 20-80 % loss in tuber yield.

Predatory mites (mainly Typhlodromalus aripo and T. manihoti) introduced from South America, the home of the cassava green mite, have given effective control of the cassava green mites in Africa (Yaninek and Hanna, 2003).

What to do:
  • Whenever possible, use varieties with good tolerance to green mites (Examples from West Africa: "BEN 86052", "MS6" and "NR8082") (James et al, 2000).
  • Use clean plant material for planting.
  • Plant at the onset of the rains to encourage vigorous growth and thereby increase tolerance to mite attack. Cassava plants aged 2-9 months are the most vulnerable to infestation.
  • Practise intercropping. Cassava intercropped with pigeon pea has been reported to suffer less damage from cassava green mite than that grown on a pure stand in Nigeria. Higher tuber yields were obtained when cassava was intercropped with pigeon pea in triple and double rows than when it was alternated in a single row or in a pure stand (Ezulike and Egwuatu, 1993).
Cassava green mite
© F. Haas, icipe

Cassava gr…

Cassava gr…

Cassava scales (Aonidomytilus albus)

It is a mussel-shaped scale with an elongated silvery-white cover and about 2-2.5 mm long. This scale may cover the stem with conspicuous white secretions, and eventually the leaves. This scale sucks from the stem and dehydrates it. The leaves of attacked plants turn pale, wilt and drop off. Severely attacked plants are stunted and yield poorly. Scale attack can kill cassava plants, in particular plants weakened by previous insect attack and drought. Stem cuttings derived from infested stem portions normally do not sprout.

What to do:
  • Apply of organic matter to improve soil fertility.
  • Selection of clean (scale free) planting material.
  • Destroy infested stems.
  • Avoid use of pesticides in the cassava field or in neighbouring crops, which may kill natural enemies.
Scales
© USDA ARS, Bugwood.org

Grasshoppers (Zonocerus variegatus)

Grasshoppers such as the variegated grasshopper (West to East Africa south of the Sahara), and the elegant grasshopper (Z. elegans) (Southern Africa and East Africa) are brightly coloured grasshoppers.

Adults are dark green with yellow, black and orange marking on their bodies. Nymphs are black with yellow markings on the body, legs and antenna and wing pads. Female grasshoppers lay many eggs just below the surface of the soil in the shade under evergreen plants, usually outside cassava fields. Eggs are laid in masses of froth, which harden to form sponge-like packets, known as egg pods, which look like tiny groundnut pods. Eggs start to hatch at the beginning of the main dry season.

Grasshoppers attack a wide range of crops mainly in the seedling stage. They feed on cassava plants, chewing leaves and stemsand may cause defoliation and debark stems. This is particularly severe in fields next to the bush when the dry season is prolonged.

What to do:
  • Hand pick grasshoppers. This is feasible in small plots.
  • Locate and dig egg-laying sites to expose and destroy the eggs before they start to hatch early in the dry season. However, egg pod destruction has to be done over a wide area in the wet season in order to be effective. This will require participation of farmers on many neighbouring farms. If only one neighbour destroys the eggs in his/her farm, the grasshoppers will later invade the farm from the neighbouring farms and bushes.
  • When available, use biopesticides. IITA researchers and partners have developed an environmental friendly biopesticide "Green Muscle®". It is based on a naturally occurring fungus strain indigenous to Africa (Metarhizium anisopliae) which is deadly to locusts and grasshoppers but reportedly does not damage other insects, plants, animals, or people. Typically 70 to 100% mortality rates were obtained after 8 to 28 days of application ( www.iita.org). The bioinsecticide "Green Muscle®" is effective in grasshopper management in outbreak situations. However, it is costly and currently, it is only available in South Africa and West Africa.
  • Use neem extracts. Neem protects cassava from grasshopper damage. It acts as antifeedant (grasshoppers stop feeding when exposed to neem products) and affects development of the grasshoppers (Nicol et al, 1995; Olaoifa and Adenuga, 1988).
    In Nigeria, the following neem products have given good control of Z. variegatus on cassava: 1.) Emulsifiable concentrate of neem oil at 0.5% to 2% applied at 8-day intervals or at 3-4% at 10-day intervals, 2.) Aqueous neem kernel water extracts (NSKE) at 7-10% applied every 12 days and aqueous neem leaf water extracts (NLWE) 50% applied every 6 days. Aqueous extracts from neem leaves were less effective than neem seed extracts (Olaoifa and Adenuga, 1988). For more information on neem click here.
Grasshoppers
© Georg Goergen (Courtesy of EcoPort, www.ecoport.org)

Larger grain borer (Prostephanus truncatus)

The larger grain borer has been found infesting cassava chips in storage particularly during the rainy season in West Africa. This beetle is currently the most serious pest of dried cassava in storage. Weight losses as high as 70% after 4 months of storage have been reported elsewhere.

What to do:
  • Use botanicals or plant parts to protect stored cassava. There are reports in Kenya, that the larger grain borer can be effectively repelled by storing cassava or grains with a fairly large amount of dried lantana or eucalyptus leaves (Personal communication, field officer of Meru herbs). Neem is also reported to be effective. For more information on neem click here
Larger grain borer
© NRI/MAFF. Reproduced from the Crop Protection Compendium, 2004 Edition. © CAB International, Wallingford, UK, 2004

The cassava mealybug (Phenacoccus manihoti)

The cassava mealybug is pinkish in colour. Its body is surrounded by very short filaments, and covered with a fine coating of wax. Adults are 0.5-1.4 mm long. This mealybug does not have males. Females live for about 20 days and lay 400 eggs in average. The lifecycle from egg to adult is completed in about 1 month at 27°C. It reproduces throughout the year and it reaches peak densities during the dry season. Mealybugs are dispersed by wind and through planting material.

The cassava mealybug strongly prefers cassava and other Manihot species; other host crops and wild hosts are only marginally infested. It sucks sap at cassava shoot tips, on the lower surface of leaves, and on stems. During feeding the mealybug injects a toxin into the cassava plant causing deformation of terminal shoots, which become stunted, resulting in compression of terminal leaves into "bunchy tops". The length of internodes is reduced, and stems are distorted. When attack is severe plants die, starting at the plant tip, where most mealybugs are found.

Mealybug attack results in leaf loss and poor quality planting material (stem cuttings) due to dieback and weakening of stems used for crop propagation. Tuber losses have been estimated up to 80%. The pest-induced defoliation reduces availability of healthy leaves, which are consumed as leafy vegetables in most of West and Central Africa. After the pest cripples plant growth, weed and erosion sometimes lead to total destruction of the crops. In general, yield losses depend upon age of plant when attacked, length of dry season, severity of attack and general conditions of the plant. Mealybug damage is more severe in the dry than in the wet season.

The cassava mealybug was accidentally introduced to Africa from South America. After the first reports in the 1970s, the insect became the major cassava pest within a few years and spread rapidly through most of the African cassava belt. The outbreak led to famine in several countries where cassava is a staple crop and particularly important in times of drought. In an attempt to control this pest natural enemies, mainly parasitic wasps and ladybird beetles, were introduced from South America.

The most effective has been the parasitic wasp (Apoanagyrus (=Epidinocarsis) lopezi), which has kept this mealybug at low levels, resulting on significant reduction of yield losses in most areas in Africa (Neuenschwander, 2003).

What to do:
  • Plant early in the rainy season to allow the cassava plants a good growth before the dry season. Strong plants are more likely to withstand pest attacks.
  • Use soil amendments and mulch to avoid moisture stress in sandy or poor soils. Mealybug numbers are higher on cassava grown on poor, sandy soils, and may cause damage in spite of the presence of natural enemies.
  • Avoid using infested plant material. Before planting cutting can be treated with hot water [by immersing them in heated water (mixing equal volumes of boiling and cold water) for 5-10 minutes just before planting] to kill all insects/mites and to avoid transfer into the newly planted field. For more information on hot water treatment click here
  • Avoid using pesticides on crops surrounding cassava fields. Although, no pesticides are used on cassava in Africa, insecticide drift from neighbouring fields may affect natural enemies that keep mealybugs and other pests under control.
  • Use of manure or other fertilisers can result in a reduction in the mealybug population because improved nutrition results in the production of larger parasitoid wasps with higher fertility levels. Mulch and fertilizer use also enhances the antibiotic properties of cassava against mealybug infestation.
Cassava mealybug
© G. Goergen (Courtesy of EcoPort, www.ecoport.org)

Cassava me…

Parasitic …

Mealybug i…

Post harvest diseases

Some fungi growth on cassava chips, usually when the moisture content of cassava chips exceeds 14%, making them unfit for feed and food. A survey of cassava chips processing areas of West Africa has indicated that the most common fungi were Rhizopus sp. and Aspergillus sp. (IITA, 1996).

What to do:

Red spider mites (Oligonychus gossypii and Tetranychus spp.)

Several species of red spider mites also occur on cassava, mostly on the older leaves. Adults are about 0.6 mm long. Initial symptoms are yellowish pinpricks along the main vein of mature leaves. Spider mites produce protective webbing that can be readily seen on the plant. Attacked leaves turn reddish, brown or rusty in colour. Under severe mite attack, leaves die and drop beginning with older leaves. Most damage occurs at the beginning of the dry season.

What to do:
  • Conserve natural enemies. Local natural enemies usually control these spider mites and no further control measures are needed.
  • Avoid planting next to infested fields.
  • Avoid use of broad-spectrum pesticides, in particular pyrethroids; this may lead to spider mite outbreaks.
Spider mites
© Image supplied by Warwick HRI, University of Warwick

Storage pests

A number of beetles feed on dry cassava causing post harvest losses. In Benin Republic the most common are Dinoderus sp., Carpophilus sp., the coffee bean weevil (Araecerus fasciculatus), the lesser grain borer (Rhizopertha dominica), and more recently, the larger grain borer (Prostephanus truncatus). (see below)

Infestation by these insects is heavier in the rainy season than in the dry season, is more prevalent in the humid zone than in the savannah, and is found more in large chips than in smaller ones. Maximum infestation was found after 6 to 8 months in storage, at which time chips would fall into dust when squeezed (Bokanga, IITA, FAO).

What to do:
  • Use botanicals or plant parts to protect stored cassava. There are reports in Kenya, that the larger grain borer can be effectively repelled by storing cassava or grains with a fairly large amount of dried lantana or eucalyptus leaves (Personal communication, field officer of Meru herbs). Neem is also reported to be effective. For more information on neem click here
Lesser grain borer
© Clemson University - USDA Cooperative Extension Slide Series, United States, bugwood.org

The striped mealybug (Ferrisia virgata)

It is a whitish mealybug with two longitudinal dark stripes, long glassy wax threads and two long tails. It attains a length of 4 mm. The stripped mealybug occurs on the underside of leaves near the petioles and on the stems. It sucks sap but does not inject any toxin into plants. Severely attacked plants show general symptoms of weakening but do not show distortion.
It is a minor pest of cassava, and no control is usually required as is controlled naturally by natural enemies.

What to do:
  • Select mealybug-free planting material.
Striped mealybug
© G. Goergen, Courtesy of EcoPort, www.ecoport.org

Termites

Different species of termites damage cassava stems and roots. Termites damage cassava planted late or in the dry season, in particular when the crop is still young at the peak of the dry season. They chew and eat stem cuttings which grow poorly, die and rot. The may destroy whole plantations. In older cassava plants termites chew and enter the stems. This weakens the stems and causes them to break easily.

What to do:
  • Plant early with the rains.
  • Avoid planting on very dry land or on termite mounds.
Termites
© A. M. Varela, icipe

Whiteflies (Bemisia tabaci, Aleurodicus dispersus)

Several species of whiteflies are found on cassava in Africa. Feeding causes direct damage, which may cause considerable reduction in root yield if prolonged feeding occurs. Some whiteflies cause major damage to cassava as vectors of cassava viruses. The spiralling whitefly (Aleurodicus dispersus) was reported as a new pest of cassava in West Africa in the early 90s.
The adults and nymphs of this whitefly occur in large numbers on the lower surfaces of leaves covered with large amount of white waxy material. Females lay eggs on the lower leaf surface in spiral patterns (like fingerprints) of white material secreted by the female. This whitefly sucks sap from cassava leaves. It excretes large amounts of honeydew, which supports the growth of black sooty mould on the plant, causing premature fall of older leaves.

The tobacco whitefly (Bemisia tabaci) transmits the African cassava mosaic virus, one of the most important factors limiting production in Africa. The adults and nymphs of the tobacco whitefly occur on the lower surface of young leaves. They are not covered with white material. The nymphs appear as pale yellow oval specks to the naked eye.

What to do:
  • Conserve natural enemies. Parasitic wasps in particular are very important for natural control of whiteflies. For instance Encarsia formosa, natural enemy of the tobacco whitefly, and Encarsia haitiensis a natural enemy of the spiralling whitefly (Neuenschwander, 1998; James, et al, 2000).
Whiteflies
© B. Nyambo, A. A. Seif, icipe

Whiteflies

Whiteflies…
General Information and Agronomic Aspects
Geographical Distribution of Cassava in Africa
Cassava typically grows as a shrub. Cassava is native of Latin America and was introduced to the African continent by Portuguese traders in the late 16th century.

Cassava is grown on an estimated 80 million hectares in 34 African countries. It is an important crop in subsistence farming, as it requires few production skills or inputs. It is drought tolerant and produces reasonable yields under adverse conditions. Most important is its ability to remain in the soil as a famine reserve. Other factors that make cassava popular with small-scale farmers, particularly in Africa, are that it requires little labour in its production and there are no labour peaks because the necessary operations in its production can be spread throughout the year, and its yields fluctuate less than those of cereals.

The storage root (some people refer to it as "tuber") is a major source of energy and the leaves, which contain a high level of vitamin A and up to 17% protein, are often used as green vegetables. Its limitations are its poor nutritive value (mainly carbohydrates) and its cyanogenic glucoside content (HCN) that can lead to poisoning unless precautions (proper peeling/soaking in water/fermenting/drying/cooking) are taken during preparation of the tubers. The latter is only applicable to bitter cassava varieties. Sweet varieties can even be eaten raw and fresh as they have very low content of HCN.

The main diseases affecting cassava are African cassava mosaic virus (ACMV), cassava bacterial blight, cassava anthracnose, and root rot. Pests and diseases, in combination with poor agronomic practices cause high yield losses in Africa. While biological and chemical control practices are available for other pests and diseases attacking cassava, ACMV is difficult to control. In severe cases, plants become stunted. In fact, this disease can cause up to 60% yield loss, and no biological or chemical control is now available to farmers. Given the vegetative propagation method used for cassava, availability of clean planting material for propagation is a major constraint, since white flies and infescted planting material transmit the disease.

While cassava production demands few external inputs, labour and planting material are main costs of production. As a root crop, cassava requires a lot of labour to harvest. The production of cassava is dependent on a supply of good quality stem cuttings. The multiplication rate of these vegetative planting materials is very low, compared to grain crops, which are propagated by true seeds. Postharvest deterioration of cassava is a major constraint. Cassava stem cuttings are bulky and highly perishable, drying up within a few days. Consequently, roots must be processed into a storable form soon after harvest. Farmers recognise postharvest loss as a major risk factor in cassava production. Nevertheless, the rapid postharvest perishability might lead to comparative disadvantages for small-scale producers linked to small-scale processing units.

Furthermore, many cassava varieties contain cyanogenic glucosides, and inadequate processing can lead to high toxicity. Various processing methods, such as grating, sun drying, and fermenting, are used to reduce the cyanide content.

Varieties
A number of both local and improved varieties exist in Kenya:
1. Coast region
a.) Local types I "Kibanda meno" - very sweet
II "Katsunga" - leaves taste like wild lettuce when cooked
b) Improved types I "Kaleso" (46106/27) - high yielding, for human consumption
II "Guso" - Better yielder than Kaleso. Also for human consumption
III "5543/156" - It is a high yielding variety for livestock. It is bitter.
2. Eastern Region Katumani I "KME 2" - Sweet, less fibrous and has low cyanide content
II "KME 61" - Bitter and more fibrous than KME
3. Western Kenya I "2200", "Tereka", "Serere", "Adhiambo lera", "CKI", "TMS 60142", "BAO"
"Migyeera", "SS 4", "MH 95/0183", "MM 96/2480", "MM 96/4884", "MM 96/5280", "MM 96/5588", "MM 97/2270"

Cassava KME 2, 6 months old
© A.A.Seif, icipe
Cassava KME 2, 12 months
© A.A.Seif, icipe
Cassava KME 2, 18 months old
© A.A.Seif, icipe

For more information on these varieties please contact the Kenya Agriculture Research Institute (KARI)

Cassava varieties in coastal and eastern Kenya (KARI/KEPHIS)
Variety Optimal production altitude range (masl) (region) Maturity (months) Tuber yield (t/ha) Special attributes
"5543/156" 1-500 (coast/eastern lowlands) 10-12 40-50 Tolerant to ACMD; bitter
"Guso" 1-700 (coast/eastern lowlands) 12-15 20-40 Resistant to (ACMD); sweet
"Kaleso" ("46106/27") 1-1500 (coast /eastern) 10-12 25-30 Tolerant to ACMD and cassava brown streak disease (CBSD); sweet
"Karembo" ("KME-08-05") 15-1200 (coast/eastern) 8 50-70 Tolerant to ACMD and CBSD; sweet; short with open structure
"Karibuni" ("KME-08-01") 15-1200 (coast/eastern) 8-12 50-70 Tolerant to ACMD and CBSD; sweet; high branching; good for intercropping
"Kibanda Meno" 1-500 6-8 20-30 Very susceptible to ACMD,; very sweet
"KME 1" 250-1500 (eastern) 12-14 20 Sweet
"KME 2" 250-1500 (eastern) 8-10 40 Tolerant to ACMD; sweet
"KME 3" 250-1500 (eastern) 8-10 40 Tolerant to ACMD; sweet
"KME 4" 250-1500 (eastern) 8-10 40 Tolerant to ACMD; sweet
"KME 61" 250-1500 (eastern) 14 35 Tolerant to ACMD; bitter
"Mucericeri" 250-1750 (eastern) 12-14 20 Sweet
"Nzalauka" ("KME-08-06") 15-1200 (coast/eastern) 6-8 50-70 Tolerant to ACMD and CBSD; sweet; straight stems ideal for intercropping
"Shibe" ("KME-08-04") 15-1200 (coast/eastern) 8-12 50-70 Tolerant to ACMD and CBSD; sweet; straight stems ideal for intercropping
"Siri" 15-1200 (coast/eastern) 8-12 50 Tolerant to ACMD and CBSD; sweet; very short without branches
"Tajirika" ("KME-08-02") 15-1200 (coast/eastern) 8 50-70 Tolerant to ACMD and CBSD; sweet; straight stems ideal for intercropping

Examples of cassava varieties grown in Tanzania (varieties listed are resistant/tolerant to ACMD)
  • "Kachaga"
  • "191/0057"
  • "191/0063"
  • "191/0067"
  • "MM 96/0876"
  • "MM 96/3075B"
  • "MM 96/4619"
  • "MM 96/4684"
  • "MM 96/5725"
  • "MM 96/8233"
  • "MM 96/8450"
  • "SS 4"
  • "TME 14"
  • "TMS 4(2)1425"

Examples of cassava varieties grown in Uganda (varieties listed are resistant/tolerant to ACMD)
  • "Migyeera"
  • "NASE 1 to 12"
  • "SS 4"
  • "TME 14"
  • "TMS 4(2)1425"
  • "TMS 192/0067"
  • "TMS 50395"
  • "Uganda MH 97/2961"



Nutritive value per 100 g of edible portion
Raw or Cooked Cassava Food
Energy
(Calories / %Daily Value*)
Carbohydrates
(g / %DV)
Fat
(g / %DV)
Protein
(g / %DV)
Calcium
(g / %DV)
Phosphorus
(mg / %DV)
Iron
(mg / %DV)
Potassium
(mg / %DV)
Vitamin A
(I.U)
Vitamin C
(I.U)
Vitamin B 6
(I.U)
Vitamin B 12
(I.U)
Thiamine
(mg / %DV)
Riboflavin
(mg / %DV)
Ash
(g / %DV)
Cassava raw 160 / 8% 38.1 / 13% 0.3 / 0% 1.4 / 3% 16.0 / 2% 27.0 / 3% 0.3 / 1% 271 / 8% 13.0 IU / 0% 20.6 / 34% 0.1 / 4% 0.0 / 0% 0.1 / 6% 0.0 / 3% 0.6
*Percent Daily Values (DV) are based on a 2000 calorie diet. Your daily values may be higher or lower, depending on your calorie needs.


Propagation and planting
Propagation from storage roots is impossible, as the roots have no buds. Cassava is propagated through cuttings. The most suitable cuttings are 20-30 cm long and 20-25 mm in diameter (with 5-8 nodes), preferably from the middle browned-skinned portion of the stems of plants 8-14 months old. Cuttings from older, more mature parts of the stem give better yield than cuttings from younger parts, and long cuttings give higher yields than short cuttings. Select cuttings from healthy plants. Cuttings slightly infested with pests can be treated by immersion in heated water (mixing equal volumes of boiling and cold water) for 5-10 minutes just before planting.

The interval between cutting stems and planting should be as short as possible (not more than a couple of days). Cassava cuttings may be planted vertically, at an angle, or horizontally. The drier the soil the bigger the part of the stem placed in the soil. Under very dry conditions, plant cuttings at an angle and cover the larger part with soil. Vertical planting is best in sandy soils, as the roots develop deeper in the soil. Horizontal planting leads to a large number of thin stems, which may cause lodging. Moreover, the roots develop more closely to the surface and are more likely to be exposed and attacked by rodents and birds. Do not plant cuttings upside down, as this drastically reduces yield.

The spacing between plants will depend on whether cassava is grown as a sole crop or with other crops (intercropping). If cassava is being grown alone, plants should be planted 1 meter apart from each other. This means that 10.000 cuttings are required for 1 ha (4000 cuttings per acre). If cassava is being grown as an intercrop, the branching habit of both the cassava and the other crops should be considered, making sure there is enough space for the plants.

The best land for planting cassava is flat or gently sloping land. Steep slopes are easily eroded. Valleys and depression areas that usually get waterlogged are not very suitable and cassava roots do not develop well. Before planting get to know the history of the land (previous crops, types of weeds, diseases and pests).

Soil preparation varies from practically zero under shifting cultivation to ploughing, harrowing and possible ridging in more intensive cropping systems. Planting on mounds and ridges is recommended, especially for areas with rainfall of more than 1200 mm per year or in areas where soils get waterlogged (e.g. valleys and depressions). Ridging may not give higher yield, but harvesting is easier and soil erosion may be reduced, especially by contoured ridges. In sandy soils, minimum tillage and planting cassava on the flat are appropriate. Plant at the beginning of the rainy season.


Husbandry
Weeding is necessary every 3-4 weeks until 2-3 months after planting. Afterwards the canopy may cover the soil and weeding is less necessary.
Although cassava grows rather well on poor soils, it requires large amount of nutrients to produce high yields. To maintain high yields, it is necessary to maintain the fertility of the soil. Phosphorous is important for root development. Symptoms of phosphorous deficiency are stunted growth and violet or purple discolouration of the leaves. In the absence of good compost, rock phosphate can be applied if needed. Potassium is also needed by cassava and can be applied in the form of compost or wood ashes. Potassium deficiency symptoms are: stunted growth, dark leaf colour which gradually becomes paler, dry brown spots on tips and margins of the leaves and "burnt" edges of leaves.

Fertilisers and manures are usually not used by small-scale cassava growers in most African countries because, in many cases, they cannot afford such additional inputs. However, it is important to provide good growing conditions for the plants, as healthy plants are able to withstand some damage by pests and diseases. In general, cassava responds well to farmyard manure. Manure can be applied at land preparation to increase soil nutrients, to improve the soil structure, and to improve the ability of the soil to hold water.

Mulching cassava, especially after planting, is helpful when growing cassava in dry areas or on slopes.


Crop rotation and intercropping
There is a wide variety of cropping patterns and rotations with cassava. Though rotation with other crops is preferable, cassava is sometimes grown continuously on the same land, especially in dry areas not suitable for other crops. When grown in bush-fallow systems, cassava is usually planted at the end of the rotation cycle, as it still produces relatively well at lower fertility levels and also allows a smooth transition to the fallow.

Cassava when planted as an intercrop along with cowpea groundnut or tree crops like Leucaena reduces soil run-off and soil-loss. Forage yield of Leucaena improves when grown with cassava and groundnut. Canavalia or Crotalaria (legume crops) when planted as intercrops with cassava improves soil productivity.
Sow 1 row of Canavalia or Crotalaria between rows of cassava immediately after planting cassava. Let these grow until harvest. Plough after harvest to incorporate crop residues into the soil.


Harvesting
Harvesting is done either piece-meal or by uprooting whole plants. Young plants are usually harvested piece-meal, while old plants are more commonly uprooted to prevent the storage roots becoming very fibrous. As cassava roots do not keep fresh more than 2-3 days after harvesting, not all plants are harvested at once, but rather harvesting as the roots are consumed. When cassava is grown for urban markets they are harvested in bulk. Cassava is usually harvested 9-12 months after planting. It is sometimes harvested earlier if needed for food. Storage roots become too woody if harvesting is delayed. Early maturing varieties are ready for harvesting at 6 months while late maturing varieties are ready 12 months after planting.


Storage
Cassava does not store well when fresh and therefore has to be peeled, chopped and dried in the sun. It can then be stored in the form of chips or flour under dry conditions.

Average yields are between 3-4 tons of fresh tubers per acre (7.5-10 tons per ha) although with reasonable care and attention yields of up to 10 tons per acre (25 tons per ha) and more are possible. The ratio of fresh tubers to peeled and dried chips is about 3:1.


Marketing
Manual from ITTA Starting a cassava farm

Of the world production of cassava, 65% is used directly for human consumption, 20% for animal feed and the remaining 15% for starch and industrial uses (alcohol production). In Africa, stems are often used as firewood.


Climate conditions, soil and water management
In equatorial areas, cassava can be grown up to 1500 m altitude. The optimum temperature range is 20-30°. Specific cultivars are necessary for successful cultivation at an average temperature of 20°.
Cassava is grown in regions with 500-6000 mm of rainfall per year. Optimum annual rainfall is 1000-1500 mm, without distinct dry periods.
Once established, cassava can resist severe drought. With prolonged periods of drought, cassava plants shed their leaves but resume growth after the rains start, making it a suitable crop in areas with uncertain rainfall distribution. Because of its drought resistance, in many regions cassava is planted as a reserve crop against famine in dry years. Good drainage is essential for cassava; the crop does not tolerate water logging. High irradiance is preferred.

Best growth and yield are obtained on fertile sandy loams. Cassava is able to produce reasonable yields on severely depleted or even eroded soils where other crops fail. Gravelly or stony soils cause problems with root penetration and are unsuitable. Also heavy clay or other poorly drained soils are not suitable.
Cassava growth and yield are reduced drastically on saline soils and on alkaline soils with a pH above 8.0. The optimum pH is between 5.5 and 7.5, but cultivars are available that tolerate a pH as low as 4.6 or as high as 8.0. Reasonably salt-tolerant cultivars have also been selected. Very fertile soils encourage excessive foliage growth at the expense of storage roots.


Information on Pests
Information on Diseases
Information Source Links
  • AIC (2002). Field Crops Technical Handbook, Ministry of Agriculture and Rural Development, Nairobi, Kenya.
  • Bellotti, A., Smith, L., Lapointe S. (1999). Recent advances in cassava pest management. Annu. Rev. Entomol. 44: 343-70.
  • Bohlen, E. (1973). Crop pests in Tanzania and their control. Federal Agency for Economic Cooperation (bfe). Verlag Paul Parey. ISBN: 3-489-64826-9
  • CAB International (2005). Crop Protection Compendium, 2005 edition. Wallingford, UK www.cabi.org
  • Ezulike, T.O., Egwuatu RI. (1993). Effects of intercropping cassava and pigeon pea on green spider mite Mononychellus tanajoa (Bondar) infestations and on yields of the associated crops. Discovery and Innovations, 5:355-359.
  • ICTVdB Management (2006). 00.057.0.71.002. Cassava brown streak virus. In: ICTVdB - The Universal Virus Database, Columbia University, New York, USA. ICTVdB - The Universal Virus Database http://ictvonline.org
  • INPhO. Post-harvest Compendium. Cassava. www.fao.org
  • James, B., Yaninek, J., Neuenschwander, P. Cudjoe, A., Modder, W., Echendu, N. and Toko, M. (2000). Pest control in cassava farms. International Institute of Tropical Agriculture (IITA). ISBN: 978-131-174-6 www.iita.org
  • James, B., Yaninek, J., Tumanteh, A., Maroya, N., Dixon, A.R. and Kwarteng, J. (2000). Starting a cassava farm. International Institute of Tropical Agriculture (IITA). ISBN: 978-131-173-8 See also online under www.iita.org
  • Msikita, W., James, B., Nnodu, E., Legg, J., Wydra, K. and Ogbe, F. (2000). Disease control in cassava farms. International Institute of Tropical Agriculture (IITA). ISBN: 978-131-176-2 www.iita.org
  • Natural Resources International Ltd (2004). DFID Renewable Resources Research Strategy Annual Reports for 2003-2004 for Crop Post-Harvest, Crop Protection, Forestry Research, Livestock Production and Post-Harvest Fisheries research Programmes. Natural Resources International Limited, Aylesford, Kent, UK. (CD-ROM)
  • Neuenschwander, P. (1998). Impact of two accidentally introduced Encarsia species (Hymenoptera: Aphelinidae) and other biotic and abiotic factors on the spiralling whitefly (Aleurodicus dispersus (Russell) (Homoptera: Aleyrodidae), in Benin, West Africa. Biocontrol Science and Technology. 8, 163-173.
  • Neuenschwander, P. (2003). Biological control of cassava and mango mealybugs. In Biological Control in IPM Systems in Africa. Neuenschwander, P., Borgemeister, C and Langewald. J. (Editors). CABI Publishing in association with the ACP-EU Technical Centre for Agricultural and Rural Cooperation (CTA) and the Swiss Agency for Development and Cooperation (SDC). pp. 45-59. ISBN: 0-85199-639-6
  • Nicol, C. M. Y., Assadsolimani, D. C. and Langewald, J. (1995). Caelifera: Short-horned grasshoppers and locust. In "The neem tree Azadirachta indica A. Juss. And other meliaceous plants sources of unique natural products for integrated pest management, industry and other purposes". Pp. 233- Edited by H. Schmutterer in collaboration with K. R. S. Ascher, M. B. Isman, M. Jacobson, C. M. Ketkar, W. Kraus, H. Rembolt, and R.C. Saxena. VCH. ISBN: 3-527-30054-6 r ISBN
  • Nutrition Data www.nutritiondata.com.
  • Olaifa, J. I., Adenuga, A. O. (1988). Neem products for protecting field cassava from grasshopper damage. Insect Science. Appl. Vol. 9, No.2, pp 267-270.
  • Plant Protection and Regulatory Services Directorate (PPRSD) (2000). Handbook of crop protection recommendations in Ghana: An IPM approach. Vol. 3: Root and Tuber Crops, Plantains. E. Blay, A. R. Cudjoe and M. Braun (Editors). Published by PPRSD with support of the German Development Cooperation (GTZ). ISBN: 9988-8025-6-0
  • Théberge, R.L. (Ed) (1985). Common African pests and diseases of cassava, yam, sweet potato and cocoyam. International Institute of Tropical Agriculture, IITA Ibadan, Nigeria. ISBN: 978-131-001-4
  • Yaninek, S., Hanna, R. (2003). Cassava green mite in Africa-a Unique Example of Successful Classical Biological Control of a Mite Pest on a Continental Scale. In Biological Control in IPM Systems in Africa. Neuenschwander, P., Borgemeister, C and Langewald. J. (Editors). CABI Publishing in association with the ACP-EU Technical Centre for Agricultural and Rural Cooperation (CTA) and the Swiss Agency for Development and Cooperation (SDC). pp. 61-75. ISBN: 0-85199-639-6
Cassava crop
Crop rotation
Crop rotation is the practice of growing different crops in succession on the same land.
Cortex
The cortex is the bark of a plant/crop.
Diameter
Thickness or width.
Mulch
Plant material such as straw, leaves, crop residues, green manure crops, saw-dust etc. that is spread upon the surface of the soil. A mulch cover helps protect the soil from erosion and evaporation, nourishes soil life, increases soil organic matter content and provides nutrients to the crop.
Farmyard manure
Droppings and beddings of farm animals, usually of cattle.
Disinfect
To reduce, by physical or chemical means, the number of potentially harmful microorganisms in the environment, to a level that does not compromise food safety and suitability.
Fungi
Occurring worldwide, most fungi are largely invisible to the naked eye, living for the most part in soil, dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in all ecosystems in decomposing organic matter and are indispensable in nutrient cycling and exchange. Some fungi become noticeable when fruiting, either as mushrooms or molds.

Fungi are responsible for a range of serious plant diseases such as blight, grey mould, bunts, powdery mildew, and downy mildew. Crops of all kinds often suffer heavy losses.

Fungal plant diseases are usually managed with applications of chemical fungicides or heavy metals. In some cases, conventional breeding has provided fungus resistantcultivars.

Besides combatting yield losses, preventing fungal infection keeps crops free of toxic compounds produced by some pathogenic fungi. These compounds, often referred to as mycotoxins, can affect affect the immune system and disrupt hormone balances. Some mycotoxins are carcinogenic.
IPM
A combination of chemical and biological control methods, based on the concept of economic tresholds. Pest management in organic farming uses many biological control methods developed as par of IPM.
Distortion
deformation or malformation
organic
Refers to the farming system and products described in the IFOAM standard and not to 'organic chemistry'.
Fungi
Occurring worldwide, most fungi are largely invisible to the naked eye, living for the most part in soil, dead matter, and as symbionts of plants, animals, or other fungi. They perform an essential role in all ecosystems in decomposing organic matter and are indispensable in nutrient cycling and exchange. Some fungi become noticeable when fruiting, either as mushrooms or molds.

Fungi are responsible for a range of serious plant diseases such as blight, grey mould, bunts, powdery mildew, and downy mildew. Crops of all kinds often suffer heavy losses.

Fungal plant diseases are usually managed with applications of chemical fungicides or heavy metals. In some cases, conventional breeding has provided fungus resistantcultivars.

Besides combatting yield losses, preventing fungal infection keeps crops free of toxic compounds produced by some pathogenic fungi. These compounds, often referred to as mycotoxins, can affect affect the immune system and disrupt hormone balances. Some mycotoxins are carcinogenic.
Breeding
is a selection of animals to reproduce and/or to further develop desired characteristics in succeeding generations.
Internodes
Internodes is the region of a plant stem between any two nodes (i.e., the point at which leaves are attached). Buds are commonly borne at nodes in the axils of leaves (i.e, the upper angles between leaves and stems).
Predator
Animal that attacks and feeds on other animals, such as an insect (e.g. ladybird beetle), bird or spider feeding on pest insects.
Resistance
Ability of a living organism not to get affected by a disease or pest; or of a pest not to be affected by a pesticide.

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.
Resistance
Ability of a living organism not to get affected by a disease or pest; or of a pest not to be affected by a pesticide.

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.
Cultivar
Cultivar is a plant variety. It is a group of similar plants which through their structural features and performance can be identified from other varieties within the same species.
Biopesticides
Biopesticides include microbiological pesticides (based on fungi, bacteria and virus) but also botanicals (plant extracts), since they are extracted from or are products of living organisms (plants)
Necrosis
Necrosis is the death of some or all of the cells in an organ or tissue, caused by disease, physical or chemical injury.
Intercropping
Intercropping is the planting of two or more crops in the same field, usually planted in alternating rows or sections.
IPM
A combination of chemical and biological control methods, based on the concept of economic tresholds. Pest management in organic farming uses many biological control methods developed as par of IPM.
Chlorosis
Chlorosis is yellowing of leaves.