Commercial-Cassava-Production-Technical_Bulletin-Final

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Commercial Cassava Production Technical Bulletinanchor the plant to the ground; and tuberous roots, which storecarbohydrates.Growth and DevelopmentThe cassava plant has two distinct growth phases.1. The first growth phase (from planting to 8 weeks) involves theproduction of stems and leaves and the thin and thick rootsystems. During this phase, the cassava tuber begins to form.2. The second growth phase (8–72 weeks) involves the rapidgrowth of the stems and leaves, as well as the swelling orbulking of the cassava tuber formed in the first phase.Cassava plant (Manihot esculenta Crantz)GROWING CONDITIONSCassava thrives best when rainfall is well distributed throughoutthe growing period. Maximum root production occurs within atemperature range of 25°C to 32°C. At higher temperatures, starchproduction in the leaves is slow. As such, the amount of cassavaproduced is reduced. Shade will also produce low yields, so thecrop should be cultivated in areas where there is full sunlight.THE CASSAVA PLANTCassava is a member of the Euphorbiaceae family of floweringplants. It is a perennial and can grow to a height of 4.5 m (15 feet).The entire plant may be viewed as a food production factory withthe end products being tubers for human and animal consumption.High tuber yields depend on the varieties cultivated and on theproper growth, development and functioning of the leaves, stemand roots supported by optimal growing conditions provided byclimatic conditions and the soil.Plant PartsLeaves: The leaves produce starches and protein, which arethe building blocks for cell growth and development. Hence, theamount and health of leaves on a cassava plant during the growthof the crop are important factors affecting yield.Stems: The stems act as the transport organs for the foodproduced in the leaves, sending it to different parts of the plant forits growth and development. Stems also provide planting materialfor subsequent crops.Roots: The cassava plant has three types of roots: fine, whiteroots, which absorb water and nutrients; thick roots, whichSOILA good soil is one of the most important factors required for highcassava yields. The crop requires adequate root room to expand,so the best soil is loose (friable) with an abundance of availablenutrients for healthy plant growth.Soils can be acid with a pH less than 7 or alkaline with a pH greaterthan 7. Cassava can tolerate soils within a wide range, from pH4.0 to pH 8.0. However, the best pH range for growing cassava is5.5–6.5. Limestone should be incorporated into more acidic soilsat 3 to 4 months before planting, using a rate of 2 to 4 tons perhectare, depending on the level of acidity. Liming acid soils hasmany benefits. It reduces the uptake of aluminium and iron, whichare toxic to cassava plants; provides calcium for proper cell wallformation; and enables good bacteria to decompose soil organicmatter making nutrients available for plant growth.Avoid fields that are prone to flooding, since most cassava varietiescannot withstand prolonged waterlogged conditions. Excessivewater will cause the tubers to rot, producing unmarketable tubersthat deteriorate rapidly. Always choose sites that can shelter theplants from fierce winds.4
Commercial Cassava Production Technical BulletinLAND PREPARATIONThe land should be well prepared to allow optimal tuberdevelopment. Clear the site of all grass, brush and trees. Plough,rotavate and ridge the soil using tractor drawn implements. Formthe ridges 1–1.5 m [approx. 3–4.5 ft] apart and 45 cm to 60 cm[approx.18–24 in] high. In hilly areas, plough along the contour.Perform subsoiling (deep tilling) to break up the soil below the topsoil. This will ensure good drainage. A good farming practice is toallow the ploughed soil to remain exposed to the sun for 2 weeksto a month. This helps to kill deeply embedded weed seeds. Asecond ploughing is then done in preparation for planting.The addition of manures or composted material helps inmaintaining a good soil structure; they provide nutrients for the sixto nine months that the crop is in the ground.SELECTING CUTTINGS FOR PLANTINGUse cuttings from strong, healthy cassava plants between 8 and18 months old. Younger material tends to be soft and susceptibleto dehydration. Older material lacks the food reserves necessaryfor the growth and development of the plant. Select cuttings fromthe middle portion of the stems. Using a handsaw or clean, sharpcutlass, cut stakes 20–30 cm [8–12 in] long with an average of9–12 nodes. Sterilize cuttings in a 1% bleach solution.Diazinon® or Basudin®) and a foliar fertilizer (e.g. Nutrex®). All ofthese should be used at the manufacturer’s recommended rates.STORING PLANTING MATERIALIdeally, cuttings should be planted immediately after they are cutand treated. The pieces dehydrate quickly when stored under hightemperatures (32ºC–36ºC) and lose their ability to germinate. Ifthe cuttings must be stored, select long pieces, preferably 30–50 cm [12–20 in], dip them in a fungicide / insecticide / nutrientsolution, allow the solution to dry then place them in a shaded andwell-ventilated area. Use a watering can or hose to wet the storedcuttings periodically.PRODUCING HIGH-QUALITY CASSAVAPLANTING MATERIALThere are two systems for producing high-quality cassava plantingmaterial, the mini-stem technique and tissue culture. Farmers canperform the mini-stem technique themselves, while the tissueculture method is normally done in a tissue culture laboratory.Mini-stem TechniqueThe mini-stem technique uses small stem pieces, which meansthat a single cassava stem will yield more planting material thanthe conventional method. A three-foot [90 cm] single stem with80–100 intact nodes will normally produce 3 plants, each 30 cmlong with the conventional method. The same stem will produce40–50 two-node cuttings or 20–25 four-node cuttings using themini-stem technique.Examples of types of planting material from left to right - too young, too old, correctTREATING PLANTING MATERIALPlanting material should be dipped in a fungicide / insecticide/ nutrient solution for 5 minutes to protect the crop from pests.A possible solution is copper hydroxide (e.g. Kocide 606®,Manzate® or Tri-Miltox forte®), a broad spectrum insecticide (e.g.Cut as many 2–4 node stempieces, or mini-stems, fromhealthy cassava plants between8 and 18 months old. Sprout theselected stem pieces in seedlingtrays, propagation bins, nurserybeds or polythene bags. This willtake 2–4 weeks. Use a foliar spraylike Nutrex® to provide major andminor nutrients and so enhanceplant vigour. Periodically examinethe young leaves for pests anddiseases, identify any infestationor damage, and use appropriatecontrol measures.Examples of suitable material [left],which will be cut into two-node cuttings[right]5
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Commercial-Cassava-Production-Technical_Bulletin-Final

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