I hope you remember this is the second lesson in this series of cassava farming. In case you missed the first lesson here is the link. Today, I shall be talking about the second lesson; which is: How To Start Cassava Farming And Select The Best Cassava Varieties!
How To Select The Best Cassava Varieties To Plant?
The best cassava varieties are those that are liked by consumers, grow fast, give good yields, store well in the soil and are tolerant to major pests, and diseases. The particular variety chosen by a farmer depends on her/his objectives for planting the crop, and the factors looked for in selecting cassava varieties usually include the following.
Look for varieties with high dry matter and good food quality:
Cassava storage roots consist mainly of water and dry matter. The dry matter is mainly starch and a little bit of fiber. The percentage of dry matter in the roots determines the quantity and quality of the products obtained after the roots are processed. Cassava varieties whose storage roots have 30% or more dry matter are said to have high dry matter content. Such varieties produce good quality products and are profitable for growers and market women.
Look for varieties with good mealiness:
Mealiness refers to the cooking ability of cassava storage roots without processing. Mealy varieties are commonly called “sweet” cassava whilst non-mealy varieties are called “bitter” cassava. Bitter cassava requires processing before consumption and this is related to the total cyanide content (referred to as cyanogenic potential, CNP) in the storage roots. The higher the CNP of a variety, the greater the need to process its storage roots for safe consumption. If cassava leaves will be eaten, you can also consider the cooking quality of the leaves.
Look for varieties that bulk early:
Bulking refers to the swelling of the storage roots as they are filled with stored food. Varieties that bulk early are better able to offset losses in storage root yield caused by weed competition, leaf-feeding pests, and disease than late maturing varieties.
Look for varieties with good ground Storability:
Ground storability is the ability of the mature cassava storage roots to stay in the ground for a long time without getting spoiled. Good ground storability prolongs the period over which the crop can be harvested.
Look for varieties that are tolerant to weeds, pests, and diseases:
Some cassava varieties tolerate weeds, pests, and diseases better than others. In selecting a variety to grow, it is advisable to consider how well the variety can compete with weeds, and resist pests and diseases.
Such varieties are able to develop a lot of branches and leaves quickly to shade the ground and prevent weeds from growing vigorously and becoming a problem. You can also find out if the variety has other features you may want
How To Select Healthy Cassava Stem Cuttings?
The most common sources of cassava stem planting material are farmers’ own farms. Occasionally, cassava stem cuttings are sold at village and town markets.
Many cassava pests and diseases are stem-borne and spread by distribution, sale, and planting of infested or diseased stem cuttings. By planting healthy stem cuttings, you can greatly reduce
the spread and damage caused by these cassava pests and diseases. The following guidelines will assist you to avoid unhealthy stem cuttings and to select healthy planting material for a healthy crop of cassava.
Look for healthy cassava plants:
Select healthy cassava plants in the farm. Healthy cassava plants have robust stems and branches, lush foliage, and minimal stem and leaf damage by pests and diseases. From each plant select the middle brown-skinned portions of stems as stem cuttings.
Avoid plants with pests and diseases:
In selecting cassava plants as sources of stem cuttings, you should avoid those infected with these pests and diseases. The common stem borne cassava pests and diseases are cassava mealybug, cassava green mite, spiraling white-fly, white scale insect, cassava mosaic disease, cassava bacterial blight, cassava anthracnose disease, and cassava bud necrosis.
The cassava mealybug:
Phenacoccus manihoti, occurs on cassava leaves, shoot tips, petioles, and stems. The mealybugs are covered with white waxy secretions. Cassava mealybug damage symptoms include shortened internode lengths, compression of terminal leaves together into “bunchy tops”, distortion of stem portions, defoliation, and “candlestick” appearance of shoot tip. The insects survive on cassava stems and leaves and are easily carried to new fields in this way.
The cassava green mite,
Mononychellus tanajoa, occurs on the undersurfaces of young leaves, green stems, and axilliary buds of cassava. The mites appear as yellowish green specks to the naked eye. Mites survive on cassava stems and leaves and are easily carried to new fields in this way. Cassava green mite damage symptoms include yellow chlorotic leaf spots (like pin pricks) on the upper leaf surfaces, narrowed and smaller leaves, “candlestick” appearance of the shoot tip, and stunted cassava plants.
The spiraling whitefly,
Aleurodicus dispersus, damages cassava by sucking sap from the leaves. Colonies of the insect occur on the undersurfaces of cassava leaves and are covered with white waxy secretions similar to those of the cassava mealybug. Spiraling whitefly eggs occur in spiral patterns of wax tracks, mostly on the undersurfaces of leaves. Symptoms of whitefly damage are black sooty mold on the upper leaf surfaces, petioles, and stems, and premature leaf fall of older leaves. The insects survive on cassava leaves and stems and are easily carried to new fields in this way.
The white scale,
Aonidomytilus albus, covers cassava stem surfaces with conspicuous white waxy secretions. The insect sucks sap from the stem and dehydrates it. Stem cuttings derived from affected stem portions normally do not sprout. The insects survive on cassava stems and leaf petioles and are easily carried to new fields in this way.
Cassava mosaic disease is caused by a virus which occurs inside cassava stems. Symptoms of cassava mosaic disease damage are patches of normal green leaf color mixed with light green and yellow chlorotic areas in a mosaic pattern. Generally, plants with these symptoms should be avoided as sources of stem planting material. However, the disease is very common in Africa and it is sometimes difficult to find cassava plants that are completely free from the disease.
You can, however, reduce cassava mosaic disease problems by selecting stem cuttings from cassava stem branches and not from the main stems. Stem cuttings from the branches are more likely to sprout into disease-free plants than stem cuttings from the main stems.
Cassava bacterial blight is caused by a bacterium which occurs inside cassava stems. The disease damage symptoms are angular leaf spots on the under leaf surfaces, leaf blighting and wilting, gum exudate on the stems, and shoot tip die-back. Avoid selecting stem cuttings from plants with these symptoms.
Cassava anthracnose disease is caused by a fungus which occurs on the surface of cassava stems. The disease damage symptoms are cankers (“sores”) on the stem and bases of leaf petioles. The disease reduces the sprouting ability of stem cuttings.
Cassava bud necrosis is caused by a fungus which grows on the surface of cassava stems covering the axilliary buds or the “eyes” of stem cuttings. The affected buds die, and the sprouting ability of stem cuttings is reduced.