Stockplant management

What is vegetative multiplication?

Getting enough planting stock, but not directly from seeds (A 3).

What's the advantage of that?

1. Trees with desirable, inherited features can be used directly to produce improved planting stock (A 10–13).
2. Plants can be produced each year in species with seed problems (A 61).

How do I set about it?

By establishing stockplants that will supply enough of the right type (A 6) of cuttings for rooting, by:

1. planting and managing a stockplant area with the best available clones (A 11); and
2. felling and coppicing selected larger trees (A 12).

What are the snags?

Here are some common ones:

Problem 1 - cuttings are not of the right kind;
Problem 2 - not enough cuttings are produced;
Problem 3 - shoots are only available at one time of year;
Problem 4 - cuttings don't root well;
Problem 5 - coppiced stumps stop producing;
Problem 6 - the planted stockplants get older, producing poor shoots.

How do I get over these difficulties?

Problem 1 - prune stockplants to encourage good shoots (A 6, 21, 25).
Problem 2 - plant plenty of rows of each clone; improve fertility of soil (A 22, 27).
Problem 3 - water during the dry season (A 26).
Problem 4 - cut back (or coppice) stockplants (A 25); introduce shading (A 24); try other clones; improve propagation conditions (A 30–36).
Problem 5 - try watering in the dry season (A 26), or adding mulch or a little fertiliser (A 27); don't rely only on the stump, but also plant the clone in a stockplant area (A 22) and keep some plants in large containers (A 23).
Problem 6 - try re-coppicing or heavy pruning (A 25); if necessary plant a new set of stockplants raised from juvenile cuttings (A 6, 21).

Won't numbers always be low at first?

Often yes, because young seedlings or cuttings used as stockplants don't yield many cuttings, so there are few plants of each clone in the early stages.

How can I speed up multiplication?

1. Plant most of the early batches of rooted cuttings as stockplants;
2. Use coppice stumps (A 21) as these can usually produce many cuttings repeatedly;
3. Before selected clones are available, accept untested seedlings as stockplants for bulk production of unimproved cuttings;
4. Later on, plant many stockplants of the most promising clones.

Are there any general hints for stockplant management?

1. Plant stockplants in a place that is easy to get to;
2. Interplant with a shrub such as Leucaena so that cuttings taken from different clones will not get mixed up (A 11, 22);
3. Arrange a reliable watering system, especially if planting and harvesting are to continue during the dry season (A 26);
4. Visit them regularly each week, to see whether they are ready yet for harvesting cuttings, and to check for any damage, weeds or pests and diseases (A 52);
5. Don't let the stockplants grow tall;
6. Before clones have been selected, avoid taking most of the cuttings from the bushiest stockplants. This could turn out to be negative selection towards branchier planting stock!

What are coppice stumps needed for?

They provide a valuable source of juvenile shoots to take as cuttings, especially useful when starting clones from selected trees (A 3, A 11–12).

Do all trees form coppice shoots when felled?

Most broad-leaved trees coppice, but only a few conifers do so.

If a species coppices, does every tree do so?

Clonal differences were found when 15 year old Triplochiton scleroxylon trees in Cameroon were felled at 4 different times of year. Most stumps produced a lot of vigorous coppice, some a few smaller shoots, while a few did not coppice. Six 25 year old Lovoa trichilioides produced hardly any coppice shoots, so it is best to do a few preliminary test fellings.

Will trees of any age coppice?

In general yes, but sometimes old trees may fail to do so, and very young plants may not have a large enough root system to coppice repeatedly.

At what height should the tree be felled?

At about 0.1 – 1.0 m above ground level.
This part of the trunk is most likely to produce juvenile coppice shoots that grow vertically and are easily rooted.

Where do the shoots grow out from?

From small inactive or newly-formed buds; either in the bark or on the cut surface (in wound tissue between the bark and wood).

How long does it take for coppice shoots to form?

The Triplochiton scleroxylon shoots were ready for harvesting in 1½ – 3 months, at any time of year.

Can I keep coming back to the same stumps?

Yes, provided that they are managed properly. Important points include leaving enough green leaves to keep the stump alive, maintaining moderate shade (see A 24) and pruning to stop tall, thick shoots and unsuitable branches from forming (see A 25).

How long will the stumps yield cuttings?

This depends partly on things you can't influence, like the species and the clone. But it can be extended to years by:

1. felling with the top of the stump slightly sloping, so that rain runs off rather than encouraging it to rot;
2. good management (as described here);
3. always leaving some basal leaves behind when harvesting and pruning;
4. adding a little fertiliser occasionally (A 27);
5. watering during long dry spells (A 26).

Why do the stumps need managing?

So that they continue to produce plenty of cuttings of the right kind for easy-to-root, upright growing cuttings (A 6).

What is the first step in good management?

Preventing the coppice shoots from getting too tall, or producing a lot of branches instead of vertical main stems.

How do I do that?

1. By harvesting cuttings frequently, rather than occasionally;
2. By often pruning back taller, thicker stems, leaving 2–3 basal leaves;
3. By pruning to encourage shoots with main stem characteristics (A 6, A 25).

What else is important?

(A) Light - felling the tree usually leaves a gap amongst the crowns in the stand that gives the right amount and kind of light to the coppice stump below (A 24). However, it may become too shady because of:

1. displacement of woody climbers during felling;
2. increased growth of saplings, vines, undergrowth and weed species;
3. rapid closing of the crown gap by new foliage.

In cases 1 & 2, give some more light (not too much) by cutting back on the shading plants as needed; for 3, maybe fell a nearby tree.

(B) Protection - against various kinds of damage:

1. cut vines before they twine and choke the shoots;
2. remove insects that are starting to eat or make nests in or near the coppice shoots - if necessary spray (A 52);
3. spray if there are signs of damaging disease, or paint the cut stump soon after felling;
4. make a strong fence if animals like hens, goats or antelopes are in the neighbourhood, or if necessary use pollarding (cutting stump above the animals' reach).
   (Note: the cuttings from pollarded trees may not be juvenile.)

Why do I need to plant a stockplant area?

1. Because stockplants in traditional containers grow slower, and are more liable to damage from drought;
2. To produce many shoots rapidly, in order to harvest plenty of cuttings;
3. To safeguard clones from the risk of extinction;
4. To multiply the numbers of plants in new clones;
5. To reduce the need for travel, especially to distant coppice stumps;
6. To have stockplants in or near the propagation nursery, so that:
   1. cuttings can be taken and set on the same day, early in the morning (A 41–44);
   2. planning and managing the stockplants are more straightforward;
   3. controlling weeds, shade, soil fertility, watering, etc is easier;
   4. protecting the stockplants is easier than with coppice stumps (A 21);
   5. inoculating them with mycorrhizal fungi or nitrogen-fixers is possible (Manual 3).

What sort of trees should I plant?

1. the species that are currently planted, plus those under trial;
2. plants growing in containers, or leafless cuttings direct (A 4);
3. with increasing genetic selection (A 10–13) as work advances:
   1. any seedling plants available;
   2. seedling plants of the better provenances;
   3. rooted cuttings from all coppice stumps;
   4. seedling plants that have scored well in a nursery test;
   5. rooted cuttings of clones that are promising in a field test;
   6. rooted cuttings of known superior clones.

Should I plant as many stockplants as possible?

It is generally best to plant most of the available material when starting a stockplant area, to reach a position quickly where many cuttings can be harvested.
However, it is safer to retain a few plants of each clone (or seed-lot) in large containers (A 23).

How should the site be prepared?

1. If possible, leave some undamaged trees to give moderate overhead shade (A 24);
2. Cut the undergrowth by hand, and fell unwanted tree with minimum disturbance;
3. Avoid tearing up or compacting the soil with a bulldozer or grader;
4. Put in the interplanted shrubs and start planting the stockplants soon after clearing, before the soil has been degraded by exposure to bright sun, wind and heavy rain-drops (A 1).
   [See also Manuals 4 & 5]

How should the planting be laid out?

Here are some general hints:

1. size of stockplant area should be sufficient for a lot of expansion;
2. spacing 1–2 m between rows; 0.5–1.5 m within each row;
3. paths 2–3 m wide, at intervals;
4. road 5–7 m wide for access;
5. clones clearly separated from each other, e.g by lines of Leucaena;
6. planting of clones from one end, leaving room for adding to each.

When should the stockplants be planted?

During the normal planting season - also possible at other times of year if regular irrigation is available, or hand watering for small numbers.

Do they need any special conditions?

Multiplication of clones is slow at first, then increasingly rapid. So it is worth spending extra effort to get the early plantings off to a flying start. This can be helped by:

1. choosing a more fertile site with a gentle slope;
2. digging larger holes;
3. interplanting with nitrogen-fixing shade plants (A 24);
4. mixing in some good soil when planting;
5. careful planting;
6. avoiding planting during dry spells;
7. nursery watering the night before planting;
8. watering if there is no rain during the first week after planting;
9. using plenty of mulch (A 27, Manual 5).

Do planted stockplants need special protection?

Putting up some temporary extra shading, for the first few weeks after planting, will protect your stockplants from stress and drying out before they have grown new roots.
Otherwise, they need the same kind of protection from damage as described for coppice stumps (A 21).

Why would I need to keep my stockplants in pots?

Young potted cuttings and seedlings are generally planted out in a stockplant area (A 22), but there may be advantages in keeping some of them at the nursery.

What advantages are there?

1. Safety: clones are less likely to be lost if a few potted plants are held back in the nursery (A 11). It is also easier to keep an eye on diseases and pests (A 52).
2. Continuous supply of cuttings: potted stockplants can be easily watered, fertilised and moved under shade (A 25–27). Cuttings can often then be harvested all the year round, and the type of shoot controlled more easily. At higher altitudes, stockplants could be kept warmer at night in a heated building, if this promotes shoot growth (Manual 3).
3. Rapid handling: because potted stockplants can be moved right into the propagation area, cuttings can be taken, prepared and set without delay (A 42–44). This reduces water loss to a minimum and cuts out the handling damage from using bags.
4. Altering the shoot position: potted stockplants can be laid horizontally or re-potted at a different angle. Changing the orientation of the shoot in relation to the force of gravity modifies apical dominance, allowing some of the other buds to sprout and grow out into vertical shoots of the main-stem type.

Aren't there some disadvantages too?

The main problems are:

1. Slow growth: the pots greatly restrict growth, so that only a few cuttings are produced.
2. Need for regular watering: unless potted stockplants are watered regularly (A 26), their growth will be further checked, and they could be damaged or even killed.
3. Rooting through: if they are allowed to root through from the pot into the ground, many of the advantages will be lost, and they will be damaged when they are moved later on.

Can anything be done about these disadvantages?

Problems (a) and (b) can be lessened by:

1. using larger containers (diameter 20–30 cm, or more), and improved potting soils (A 53) to promote better root growth;
2. using plastic pots that are white outside and black inside, or trying pots made of other materials, to avoid over-heating the root systems;

Problem (c) can be overcome by the simple methods described in A 54.

What kinds of trees are suited to large containers?

Research is needed to find this out, but species that produce many small shoots and leaves (e.g. Cupressus and some eucalypts) are more likely to be successful.

What species should not be kept a long time in containers?

Pending research results, avoid those:

1. with very strong growth and large leaves (e.g. teak);
2. that are easily damaged by water stress;
3. which rely strongly on a single tap-root;
4. are being grown to provide large, leafless cuttings.

What's the best thing to do with an new species?

Plant out most stockplants, but keep some of each clone for trials in various containers.

Why do stockplants need shade?

1. because it protects the soil they are growing in;
2. because they should grow better and produce more cuttings;
3. because the cuttings may root better.

How does it do these three things?

1. by reducing overheating, drying out and washing away of the surface soil, and encouraging the recycling of mineral nutrients (A 1);
2. by giving soil and lighting conditions more like a gap in the forest or savanna;
3. by giving the right amount, and also kind of light to the stockplants.

But won't the shade slow down the stockplants' growth?

Only if it is too dense. Moderate shading typically makes shoots elongate more than they do in full sun.

Why is the kind of light important?

When sunlight has travelled through and past green leaves, parts of it (e.g. the red and the blue) are less well represented. This ‘filtered’ shade light stimulates longer internodes and more easily rooted shoots.

What kinds of shade can I use?

Two methods using green leaves, one with dying foliage, and one with a man-made product:

Method 1: leave some large trees to provide overhead shade;
Method 2: interplant with smaller shade trees or shrubs;
Method 3: use palm leaf shade;
Method 4: use plastic shade.

Which is best?

Choose which methods are most suitable for each situation - each method has advantages and disadvantages. Advantages include:

Method 1: maintains the whole stockplant area under ‘open woodland’ conditions; and encourages diversity of mycorrhizal fungi (Manual 3);
Method 2: shade plants can be put exactly where they are needed; and species that are nitrogen-fixers can be chosen;
Method 3: very cheap, quick and easy to put up;
Method 4: gives an even shade, and lasts a long time.

Some disadvantages are:

Method 1: uneven shade; dead branches falling can be dangerous and damaging; shade trees sometimes die because of opening up, bulldozer damage, etc;
Method 2: need to be cut back regularly;
Method 3: only lasts a short time;
Method 4: not cheap; needs to be ordered.

For coppice stumps (A 21): methods 1 & 3 are often suited;
For planted stockplants (A 22): methods 2 & 4 are usually best;
For potted stockplants (A 23): use any convenient method.

Palm-leaf, and three types of plastic shadecloth.

How do plants fix nitrogen?

Certain kinds of trees, shrubs and food crop plants form nodules, a close association between their roots and micro-organisms. These can transform nitrogen gas from the atmosphere into soluble compounds that can be used by the plant (Manual 3). Nearly all are leguminous plants, although not all leguminous plants fix nitrogen.

Which kinds are useful in a stockplant area?

Leguminous shrubs, such as Flemingia rhodocarpa, which is used in stockplant areas for Robusta coffee, and those that cast a moderate shade, like Leucaena. Acacia, Delonix, Cassia, Erythrina, Gliricidia, Parkia, Prosopis and Sesbania could also be tried.

What is the best way to plant shade plants?

Close-planted in single lines between 2 rows of stockplants, as this:

1. gives fairly even shading;
2. makes it easy to cut them back;
3. allows one to walk between the stockplants (A 22);
4. keeps the clones well separated (A 11);
5. provides nitrogen to each of the stockplants (Manual 3).

What about cutting shade plants back?

Aim for the following:

1. to cut often, keeping a moderate, even, overhead shade;
2. to cut less during the dry season, to maintain shade when it is most needed, and when some leaflets or leaves may be shed;
3. to prune back strong leaders before they get out of reach;
4. to remove lower branches that get in the way;
5. to lay the pruned branches on the ground as mulch (Manual 5).

Is plastic shading easy to use?

Yes, the various kinds of shadecloth come in rolls up to 4 m wide, and can easily be joined together with a plastic tie (best done on the ground before fixing it up). It is very light in weight, and can be fastened to a simple framework of wood, bamboo, etc, strong enough to stand up to wind and rain. It should then last for several years.

Is temporary shade needed in a stockplant area?

Yes, sometimes, as for example:

1. to help stockplants or shade plants establish well, immediately after planting;
2. there is some evidence that shading stockplants for just a few weeks before taking the cuttings could encourage better rooting.

For trials with your species, consider making up some light, portable frames for temporary extra shading.
Potted stockplants can be moved from a shadier to a less shady site.

Why do stockplants need pruning?

To keep them producing plenty of the right type of shoots (A 6, 20, 21).
Note: Tying down the shoots of stockplants, or planting them obliquely also affects the number and type of shoots that grow out (A23).

Doesn't harvesting cuttings do that anyway?

It does part of the job of pruning. However, extra cutting back is usually needed, because:

1. stockplants tend to re-form strong leading shoots, which:
   1. are too thick to make good cuttings;
   2. grow too tall to reach easily from the ground;
   3. soon lose easy rooting ability;
   4. suppress the growth of the lower shoots;

2. branches need to be checked that are unsuitable for cuttings;
3. dead parts are better removed.

What should I prune with?

For thinner twigs: a sharp pair of secateurs or knife;
For thicker stems: a sharp machete or saw.

When should I prune?

1. just after harvesting cuttings;
2. before any shoot turns into a dominant leader;
3. before new shoots reach about 30–40 cm in height.

How should I do the pruning?

Allow for differences between species, but aim to:

1. make sloping rather than horizontal cuts, just above a bud;
2. cut back strong vertical shoots to 2–3 good basal leaves and buds;
3. remove shoots with a flattened, ‘branch-type’ growth habit (if the stockplant has few other leaves, just remove their tips and any growing buds);
4. try removing the tip of the strongest shoot, in order to favour the others.

Can pruning completely prevent the loss of easy rooting?

Regular pruning certainly delays the changes that happen rapidly if the stockplant is allowed to grow back into a tree (A 6). It is not yet clear whether they can be stopped altogether.

Doesn't that mean I could lose my source of clonal cuttings?

This is not yet known, but is a possibility, perhaps for example in Terminalia. However, you can:

1. coppice the planted stockplants, cutting them back near to ground level just before you expect a new flush of growth;
2. allow a few trees of each clone to grow tall, so that these could later be coppiced, if needed.

Why should I need to water stockplants?

There are three main reasons:

1. to ensure their rapid and successful establishment;
2. to encourage them to grow quickly and produce more cuttings;
3. to enable them to produce cuttings all the year round.

Won't watering make the cuttings too ‘soft’?

1. Not with leafy cuttings, as they usually root best when the shoots were growing fairly vigorously, and had not yet become very woody;
2. For non-leafy cuttings, it would be sensible to stop watering 2–3 months before you expect to take the cuttings.

But won't the rooted cuttings still be too soft to survive?

No, because they will have been ‘weaned’ (A 54), grown on and ‘hardened’ before they are ready for planting out. The ‘softness’ is just a temporary state, not a permanent feature of the trees.

Will any water do?

1. Rainwater: usually suitable, though watch out for:
   1. supply failing in dry season;
   2. toxic chemicals washed off new roofs into water tubs;
   3. workers using soap in them;
2. Mains water: usually very suitable, even if chlorinated, though it may prove expensive;
3. Stream water: usually suitable, but may run short in dry season;
4. River water: usually suitable, but could contain a lot of iron, aluminium, or industrial pollutants.

How often should I water in a stockplant area?

1. For newly planted trees: regularly every 1–3 days during the first 2 weeks, unless it rains;
   (Note: Mulch should be laid on wet soil)
2. For established stockplants: plenty of water twice a week is better than a little more frequently.
   [NOTE: if you want to stop watering during dry weather, do it gradually!]

What about coppice stumps?

These often grow well throughout the year, probably because they have a very extensive root system, perhaps with mycorrhizas. However, if there is a water supply nearby, an occasional good soaking could be useful for:

1. stumps that have very few or small shoots;
2. mulch or fertilisers applied in the dry season (A 27).

How about potted stockplants?

1. For stockplants to be planted out: daily or twice-daily watering, including weekends and holidays, unless it rains (Manual 3)
2. For stockplants held permanently in large containers: work out a watering schedule (e.g. a good soak on Mon/Wed/Fri or Mon/Thurs), which keeps the soil throughout the container moist, but not excessively so.

Don't trees get all they need from the sun, air and soil?

Yes, these are the sources of the energy and the chemical substances needed for growth of plants. However, mineral nutrients are often in short supply, making growth much slower than it could be.

Does this apply especially to stockplants?

Yes, because:

1. planted stockplants are usually grown in opened sites, where the supply of mineral nutrients is declining;
2. rapid growth is needed to produce plenty of shoots that will give good cuttings;
3. quite a lot of nutrients are being removed by repeated pruning and harvesting of cuttings, and in weeding;
4. stockplant root systems may be restricted by the removal of much of the shoot system.

What can I do to overcome these problems?

1. Leave some shade trees (A 24);
2. Interplant with nitrogen-fixing shade plants (A 24);
3. Put plenty of mulch around the stockplants (Manual 5);
4. Apply fertilisers to stockplants, including coppice stumps (A 21);
5. Inoculate stockplants with the appropriate mycorrhizal fungi (Manual 3).

Which is the best method?

A combination of techniques, starting with the first.

Does that mean that mulch is more important than fertilisers?

Yes, because:

1. restoring a woodland environment comes before trying to compensate for its loss;
2. mulching lowers the temperature of the surface soil and helps maintain its moisture content, as well as adding nutrients;
3. mulching adds organic matter to the soil;
4. mulching laid on wet soil makes the conditions more favourable for root growth, earthworms, mycorrhizas etc and encourages the recycling of nutrients;
5. using branches from interplanted nitrogen-fixing shade plants (A 24) as mulch adds extra nutrients to the stockplant area;
6. applying fertilisers is generally more expensive than mulching.

So I shouldn't use fertilisers at all?

Yes, they can be a valuable addition to the other techniques, especially if:

1. the soil is infertile - short of most nutrients;
2. there is a lack of specific main or trace elements;
3. material for mulching is in short supply;
4. research shows that they make the cuttings root better.

What fertiliser should I use?

Try a general purpose fertiliser first. It should contain N, P & K (the main nutrients - nitrogen, phosphorus and potassium) in amounts and proportions that have been selected for agricultural crops (if possible tree crops). Calcium (Ca) and sulphur (S) are usually present in NPK fertilisers; magnesium (Mg) and trace elements (micronutrients) might be required in some cases. Modern slow-release fertilisers may prove well suited to tropical conditions, where heavy rainfall can quickly dissolve and wash away most of the nutrients that have been applied. At present, however, they are more expensive.

What are trace elements?

They are chemicals that are essential for normal plant growth, but are only required in minute quantities. In fact, many of them are toxic to plants at higher doses. They are:

Boron (B)
Copper (Cu)
Iron (Fe)
Manganese (Mn)
Molybdenum (Mo)
Zinc (Zn)

How much fertiliser should I apply?

It is better to apply them in small quantities (eg. 25 g per m² NPK):

1. until trials have shown that more is needed;
2. because too much can damage the stockplants;
3. because too much of one nutrient can restrict uptake of another;
4. because the extra nutrients will probably be washed away by rain, and wasted;
5. because high levels of nutrients may restrict mycorrhizas, which are particularly important in taking up P from the soil that would not otherwise be available to the trees;
6. because large amounts could increase soil acidity (reduce pH).

When should I apply them?

1. when planting (P fertilisers);
2. after the stockplant has had time to form some new roots (others);
3. during the rains, rather than the dry season;
4. after taking cuttings, rather than before (unless fertilisers have been shown to promote subsequent rooting).

How should fertilisers be applied?

1. little and often;
2. P is best applied at the bottom of the planting hole, near to, but not touching the roots;
3. N and K (and NPK) fertilisers can be applied as a top-dressing on the mulch or soil around the stockplant, but not touching its stem or roots;
4. If the stockplants are being watered (A 26), nutrients can be applied dissolved in the water. Apply frequently at low concentrations;
5. Trace elements and urea can also be sprayed as a very dilute solution on to the leaves (foliar feeding).

How big a difference does nutrition make?

Except in very fertile, favourable sites, the differences can be very large indeed. In some cases, applying mulch and/or fertilisers could double or triple the production of cuttings.