🌿 Planting Material

Nearly all commercial cassava is propagated from stem cuttings, called stakes, not from botanical seed. Module 2 established the biology. This lesson establishes the economics, because the economics is where the trouble lives.

Compare cassava with maize or improved rice for a moment. Certified cereal seed is small, dry, storable for months, and cheap to ship across a country in a sack. A national seed company can multiply it, treat it, bag it, brand it, and sell it through a thousand agrodealers. That industry exists because the product physically permits it.

Cassava planting material permits none of that. Stakes are bulky. A hectare's worth is a truckload of woody stems, not a sack. They are perishable, deteriorating rapidly during storage and transport from dehydration, from pests and from disease. And a synthesis of the seed-systems literature states the position plainly: cassava planting materials, in themselves, have no economic value in most farming systems.

Read that phrase carefully, because it explains almost everything. It does not mean stems are useless. It means that in most farming systems nobody has been paying for them. They come free from your own field or from a neighbour who has finished harvesting and has stems to spare. There is no habit of paying, so there is no price, so there is no margin, so there is no business, so there is no formal cassava-seed industry comparable to the certified-seed trade in cereals.

Now follow the consequence, because it is not merely a supply inconvenience. It is a disease pathway.

Cassava mosaic disease and cassava brown streak disease both travel in infected stem material as well as by their whitefly vector. Cassava bacterial blight spreads through contaminated seed and stem cuttings among other routes. Cassava anthracnose damages stems so badly that infected material is associated with a 50 to 75 percent reduction in cutting viability, and severely infected stems show germination rates of only 40 to 60 percent. At least four of the six major cassava pest and disease problems move with planting material.

So the informal cutting exchange that keeps African cassava farming going, neighbour to neighbour, village to village, is also the fastest way those diseases cross a region. Nobody in that chain is doing anything wrong. A farmer giving stems to a neighbour is being generous. The system itself is the transmission route.

That is why a clean-seed multiplication and distribution scheme is a disease-control intervention, not just an input-supply convenience. When a national programme sets up seed multiplication or runs a positive-selection extension programme, it is not trying to make farmers buy something they used to get free. It is trying to break a transmission chain.

And it is why the single highest-leverage thing a learner can do against most cassava diseases, before any spray, any biological agent, any resistant variety, is to plant clean material. Clean, certified, or at minimum locally inspected. That intervention costs you attention rather than money, and it outranks everything else in the disease toolbox.

Here is the practical translation for your own farm, and it is uncomfortable at first.

Your stems are an asset. Stop treating them as harvest waste. When you dig your roots, the stems standing in that field are next season's crop, and if you burn them, feed them to livestock, or leave them in the sun for a week, you have thrown away the input you will otherwise have to beg or buy.

Be willing to refuse free material. Free stems from a field showing mosaic mottling are not free. They are a season of reduced yield, and then they are your own field's mother plants next year, and the year after. The commonest way a farm acquires a chronic disease problem is by accepting generosity without inspecting it.

Be willing to pay when paying buys inspection. If a certified or inspected source exists near you, the price is not for the wood. It is for the assurance, and in a crop with these transmission routes, the assurance is what you are actually short of.

And start thinking of a part of your farm as a multiplication block rather than a root field. Lesson 5 does the arithmetic that shows why you need one.

A stake is a piece of stem you cut and plant. Getting it right is one of the cheapest yield improvements available to you, because it costs nothing but attention at the moment of cutting.

Here are the reported practical specifications, drawn from an FAO and IAEA cassava production guide and a CIAT planting-materials chapter.

Cutting length is commonly 20 to 30 centimetres. One farmer-facing guide works with 25 centimetre sticks. Measure this rather than judging by eye, at least until your eye is trained. Cut a stick of the right length and lay it beside you as a gauge.

Nodes per cutting should be at least 5, with 5 to 8 commonly cited. A node is the point on the stem where a leaf was attached and where a bud sits. Buds are what sprout. No buds, no plant.

This figure is not decoration, and the reason is worth understanding. Cuttings with fewer than 5 nodes show reduced root production and smaller average root weight in the cited comparison. Notice that it is both, not one. Fewer roots and each root lighter. Those two losses multiply together, which is why a short-cut stake costs far more than the length of stem it saved.

Stem thickness is roughly 2 to 4 centimetres. Thickness matters because the stake lives on its own stored reserves during establishment, before it has any roots or leaves of its own. A thin stake carries a smaller pantry. It is the same reasoning behind the moisture rule in Lesson 3.

Source plant age and health is the specification most often ignored. Cuttings should be taken from healthy, mature stems of the current season's growth, visibly free of stem borer damage, mealybug and disease symptoms.

Unpack that. Current season's growth means the wood you cut should be this season's, not old woody material from further down that has already spent itself, and not the soft green tip that has not hardened. Mature means it has hardened enough to survive the cut and the wait. And visibly free of symptoms means you actually look, plant by plant, before the machete moves.

So the cutting operation has an order to it, and the order matters.

1. Select the mother plant first, standing back and looking at the whole plant. Leaves mottled or distorted with mosaic symptoms, or a stem with borer holes or mealybug, means you move to the next plant. Do not salvage the good-looking half of a diseased plant. The virus is systemic, meaning it is in the plant, not only in the part that shows.
2. Cut the stem from a selected plant and lay it aside from the rejected ones. Keep two piles and never let them mix.
3. Cut the stem into stakes of 20 to 30 centimetres, working from the mature middle portion of the stem rather than the soft top or the old base.
4. Count nodes on each stake as you cut. Any stake below five nodes goes to the discard pile.
5. Keep the stakes shaded and out of the sun the moment they are cut. Lesson 3 explains what sunlight is actually doing to them.
6. Sanitise your cutting tool between plants and especially between fields. Contaminated tools are a listed spread route for cassava bacterial blight. A cloth and clean water between plants, and a proper clean between fields, is not fussiness. It is the same logic as a clinic changing a blade.

A note on orientation before you cut. Cassava stakes have a top and a bottom, and planted upside down they sprout poorly or not at all. Keep track of which end was up as you cut. A common working habit is to cut the bottom end square and the top end at a slant so the orientation is visible on the pile even after the stakes are carried across the field.

One more discipline. Count what you cut. If you know you cut 400 stakes and planted 400, then a sprouting count at four weeks gives you a real percentage rather than an impression, and that percentage is the single best early measure of whether your material was any good. Module 3 asked you to record it per variety. Record it per batch too, because two batches of the same variety, cut and stored differently, will not perform the same.

Cuttings die of thirst. That is the plain version of this lesson and it should govern everything you do between the machete and the planting hole.

Here is the sourced figure that should anchor your practice. A reported 20 percent reduction in cutting moisture content can reduce sprouting, meaning viability, by 50 percent.

Stop and read that again, because the ratio is what makes it powerful. A one-fifth loss of moisture costs you half your plants. Not a fifth of your plants. Half. A stake is not slowly declining in proportion to how dry it gets; it falls off a cliff.

Now put that beside a normal day on a normal farm. Stakes are cut in the morning and left on the ground at the edge of the field. The sun climbs. Somebody is called away to another job. Planting starts the next day, or the day after when the rain comes. Nobody did anything visibly careless, and half the batch may already be lost before it touches soil.

That is the whole reason this lesson exists. Nothing about drying looks like damage. There is no rot to see, no insect, no symptom. The stake looks like wood, because it is wood. It just does not sprout.

So the first rule is speed. The shortest possible time between cutting and planting is the best storage system there is, and it is free. Plan the cutting around the planting, not the other way round. Cut what you will plant.

When you cannot plant immediately, storage becomes a real decision, and here is where the second sourced fact matters enormously.

Storage tolerance is highly variety-dependent, and the difference is not small. In one CIAT comparison, the variety M Col 1468 could be stored for 6 months, while M Col 1684 deteriorated within 2 to 3 weeks. Same storage conditions. Different varieties. That is an order-of-magnitude difference.

The lesson from those two names is not to look for M Col 1468, which is a research collection accession, not something in your market. The lesson is structural: the question how long can I store my cuttings has no single correct answer independent of variety. Anyone who gives you one number for all cassava is giving you a number from one variety and calling it a rule.

Which means you must find out for your own varieties, and the way to find out is to record it. Store a small marked bundle, plant a few stakes from it at two weeks, at four weeks, at eight weeks, and count sprouting each time. After one season you know your own variety's storage curve, and that knowledge is worth real money at the moment when planting is delayed by late rain.

On arrangement, one thing is reported clearly: vertical storage of bundled cuttings reduces deterioration and losses compared with horizontal storage. So bundle your stakes and stand them upright rather than laying them in a heap.

Build the rest of your storage around the moisture rule, since moisture loss is the mechanism you are fighting.

• Shade, always. Direct sun on cut stems is the fastest way to reach that 20 percent moisture loss.
• Out of the wind, because moving air dries wood faster than still air at the same temperature.
• Standing upright in bundles rather than lying in a pile.
• Bases in contact with damp soil or covered with damp material or mulch, which is common practice for keeping cut stems from drying out.
• Off the path of livestock and away from stored crops that attract rodents and insects, since pests are listed alongside dehydration and disease as causes of deterioration in storage.
• Checked. Walk past your stored stems every few days and look at them. A bundle drying at the top of the stack is a problem you can still fix.

One last piece of judgement. When you doubt a batch, test it rather than gambling a field on it. Plant twenty stakes from that batch in a corner, count sprouts at four weeks, and use the percentage to decide. Twenty stakes is a trivial cost. Replanting a hectare because a batch was dead is not, and the gaps in a poorly sprouted field will not close: they simply become weeds, exactly during the critical weed period that Module 6 covers.

Treatment is where farmers most often want a simple recipe and where a course most owes them precision instead. There are two families of pre-planting treatment reported in the literature this course is built on, and they work differently.

The first family is chemical dips. Fungicide and insecticide dips are reported in the planting-material literature, cited there by trade name. This course does not repeat those product names as a recommendation, and the reason is not squeamishness. Pesticide product availability, registration, permitted dose and safe-use rules are set by national authority and differ by country. A product legally registered for cutting treatment in one country may be unregistered, restricted or banned in the next.

So the principle is what travels, and the principle is this: a chemical dip is a targeted intervention against a named pest or pathogen, applied at a registered dose, using a product registered for that use in your country. The correct authority to ask is your national plant-protection or agrochemical regulator, usually reachable through the extension service. Ask three things: which products are registered for cassava planting-material treatment here, at what dose, and what protective equipment and re-entry rules apply. Never take dose advice from a seller with stock to move.

The second family is thermotherapy, which means heat treatment, and it is the more interesting one for a smallholder because it requires no registered product at all, only water, heat and a thermometer.

Two hot-water treatments appear in this course's reference and they are not the same treatment. Learn them as a pair, and learn why they must not be merged.

The first is hot-water immersion at 49 degrees Celsius for 49 minutes, reported in the planting-materials literature as a non-chemical thermotherapy used specifically against bacterial and vascular pathogens.

The second comes from the cassava bacterial blight literature, where hot-water treatment at 60 degrees Celsius is reported to show no sign of bacterial survival in one cited trial.

Two different temperatures, two different pathogen targets, two different sources. Do not conflate them into one cutting-treatment temperature, because there is no such single number here. If someone tells you the hot water temperature for cassava, ask which pathogen and which source they mean.

And note what is not stated for the second figure: the reference gives 60 degrees for CBB without an immersion duration you can rely on. This course will not supply one, because supplying a time nobody sourced is exactly how a plausible-sounding instruction gets people to cook their planting material or to under-treat it. If you intend to use hot-water treatment against bacterial blight, get the protocol, temperature and duration together, from your extension service or the national plant-protection service.

Here is what any farmer using heat treatment must understand about the risk, because it is real. Heat that kills a pathogen inside a stem is not far below heat that kills the stem. That is the entire difficulty of thermotherapy. It works in the narrow band where the pathogen dies and the plant tissue survives, which is why the temperature and the duration are stated together to the exact figure, and why guessing either one is dangerous. Forty-nine minutes at 49 degrees is a specific protocol, not a rough idea.

So if you are going to do it, do it properly. Use a real thermometer, not a hand in the water. Keep the water at temperature for the whole immersion rather than letting it cool as cold stems go in, which means heating a volume of water large enough for the batch. Time it. And test the protocol on a small batch, planting them and counting sprouting at four weeks, before you treat a whole season's material with a method you have not yet proved on your own varieties.

And keep the hierarchy straight. Treatment does not rescue bad material. A stake cut from a diseased mother plant, or dried to half its viability, is not repaired by a dip or a hot bath. Selection comes first, as in Lesson 2. Moisture protection comes second, as in Lesson 3. Treatment is a third layer on top of material that was already good, and any seller who offers treatment as a substitute for inspection has the order backwards.

This is the arithmetic lesson, and it is one of the most important economic facts in the whole course for anyone planning a planting-material business or simply planning to expand.

Start with the sourced figure. A single mature, healthy cassava plant typically produces only about 10 usable 20-centimetre commercial stakes.

Ten. From a whole plant, after a whole season.

Work the consequence out. At the common monocrop spacing of 1 metre by 1 metre, planting density is approximately 10,000 plants per hectare. If each of those plants gives about 10 usable stakes, then one hectare of mother plants produces about 100,000 stakes in a year, which at 10,000 plants per hectare will plant roughly 10 new hectares.

That is a multiplication ratio of about 1 to 10 per year under normal field multiplication.

A farmer-facing version of the same idea comes from an IAEA production guide: planting one 25 centimetre stick of an improved variety this year yields at least a minimum of eight sticks next year. Broadly consistent with the CIAT figure, and worth using as your conservative planning number, because a business plan built on the lower figure survives a bad year and one built on the higher figure does not.

Now feel what a ratio of 8 to 10 per year actually means, because it is slower than people expect.

Suppose you have one hectare of a new variety and you want to reach 100 hectares, which might be a cooperative's ambition or a district programme's target. Using the conservative factor of 8: after one year you have material for 8 hectares. After two years, 64. After three years, 512. So three full seasons to cross 100 hectares, and that is with every single plant kept for multiplication and none of it harvested for food or sold for roots.

That last clause is the part that hurts. Every stake you use to expand is a plant you did not eat and did not sell. Multiplication competes directly with income, season after season, which is exactly why it does not happen on its own and why national programmes have to fund it.

Compare that with maize, where a farmer buys a bag of certified seed and is planting the new genetics this season. Now you understand, in numbers, the point Module 2 made in words: a good new cassava variety travels across a country far more slowly than a good new maize seed, and that is a structural feature of the crop, not a failure of anybody's effort.

Here is how to use the arithmetic on your own farm. Work backwards from the area you intend to plant.

1. Decide the area you will plant next season and convert it to a plant count using your spacing. At 1 metre by 1 metre that is about 10,000 plants per hectare, so half a hectare needs about 5,000 stakes.
2. Divide by your conservative per-plant stake figure of 8. Five thousand divided by 8 is 625, so you need about 625 healthy mother plants standing this season to supply half a hectare next season.
3. Add a margin for rejection, because you will discard diseased plants, short stakes and stakes below five nodes. If you expect to reject one in five, divide by 0.8: 625 divided by 0.8 is about 781 plants.
4. Now go and count what you actually have that is healthy enough to cut from. The honest number, not the hopeful one.
5. The gap between those two figures is your planting-material problem, and it is far better to discover it now than on planting day when the rains have started.

One more consequence worth planning for. If multiplication competes with income, then treat it as a separate enterprise with its own piece of land. A dedicated multiplication block that you do not harvest for roots keeps the arithmetic honest, because a block you keep raiding for food will never deliver the stake numbers you calculated. Mark it, record what goes in and what comes out, and count its stakes at the end of the season against the figure you predicted. That comparison is how you learn your own true multiplication rate rather than the reported one.

Lesson 5 left you with a hard number: about eight to ten stakes per plant per year. This lesson covers what changes that number, and how honestly to think about it.

Rapid multiplication techniques exist and they change the ratio dramatically. Two are reported in this course's reference.

Shoot-induction techniques, which sit close to tissue culture, are reported to yield roughly 800 shoots per year from a single mother plant.

Leaf-and-bud mini-cutting techniques are reported to produce up to 60,000 stakes from a single mother plant within about 18 months.

Set those against the field figure of about 10 stakes per plant per year and the scale of the difference is obvious. Eight hundred is roughly eighty times field multiplication. Sixty thousand within eighteen months is in a different category altogether.

Now the honest framing, which matters more than the numbers. These are specialist, capital-intensive and skill-intensive techniques. They are not standard farmer practice, and this course is not telling you to attempt them with a machete and a field. They are the answer to a specific question: how does a clean-seed multiplication enterprise scale fast enough to serve a district. They are not the answer to how an individual smallholder plants more cassava next season.

So where does that leave you? It depends entirely on which enterprise you are building, and there are three honest positions.

The first position is the ordinary farm. You are multiplying for your own planting and perhaps a little for neighbours. Field multiplication at eight to ten is your reality. Your levers are the ones in Lessons 2, 3 and 5: cut good stakes, keep them from drying, keep a dedicated multiplication block, and plan on the conservative figure. Nothing exotic is required and nothing exotic will help.

The second position is the local multiplier. You have decided to produce planting material as a product, serving farmers around you. Field multiplication still applies, but your business depends on something the ordinary farm does not need: the ability to demonstrate that your material is clean. That means inspected mother fields, records of where material came from, separation between varieties, and a working relationship with whoever inspects or certifies planting material in your country. Your product is not stems. Your product is confidence, and stems are how it is delivered. Price it accordingly and expect to explain the price.

The third position is the district or programme scale, where rapid multiplication becomes relevant. This is institutional work, usually involving a research station, a national programme or a funded project, with the facilities and trained staff that shoot-induction or mini-cutting techniques require. If you are approached to participate in such a scheme as a grower, the right questions are who inspects the material, what happens if a batch fails inspection, and who carries that loss.

Whatever position you occupy, hold onto the reason any of this matters. Because there is no mature certified-seed market, the fastest way cassava mosaic disease and brown streak disease spread across a region is through farmers sharing infected cuttings. A clean multiplication and distribution scheme is a disease-control intervention. That is the logic behind national seed-system and positive-selection extension programmes, and it is why a multiplier who cuts corners on inspection is not merely selling a weak product. They are running an infection route with a delivery van.

There is one more reason to take clean material seriously that reaches beyond your own district. Recommended interventions in the climate literature include stricter national and international controls on the movement of planting material across borders, and prioritising replanting with clean material in current high-outbreak areas. The direction of travel is towards more control of stem movement, not less. A multiplier who already keeps records of where material came from and where it went is positioned for that. One who cannot say where a batch originated is not.

Finally, a word on ambition and arithmetic together. Rapid multiplication figures are exciting and they are real, but the binding constraint in most districts is not the biology. It is whether anyone will pay for a clean stake in a system where stems have always been free. That is a market-building problem, and Lesson 1 of this module is where it starts: with a farmer who has understood why a free stem from a mottled field is the most expensive input on the farm.