Care of cuttings

What do I need to check?

The most important thing is to see whether suitable propagation conditions are still being maintained.

What needs to be checked regularly?

Points needing to be checked once or twice every day:

1. Moisture:
   1. in poly-propagators (A 34, 51):
      1. Unless they are still wet, cover the cuttings with a fine spray of water droplets in late afternoon and early morning especially when the weather is hot and dry. In cool, moist weather, and with well constructed poly-propagators, spray only when the leaves are becoming dry.
      2. top up the water level under the rooting medium, if needed (A 31);
      3. check that the rooting medium is still moist, but don't soak it!
   2. in mist propagation (A 32):
      1. check that the mist controller is working properly;
      2. clean any mist jets that are giving uneven or poor mist bursts;
      3. see whether the rooting medium is much too wet. If the shoots are also very wet, reduce the length or frequency of bursts a little.
      4. check for leaves stopping mist from reaching some of the cuttings.
   3. for potted plants (A 53):
      1. check whether the soil is still moist, and water accordingly;
      2. look out for any signs of wilting (A 51).
2. Temperature: in poly-propagators (A 31):
   1. check that the air temperature is not getting too high in the middle part of the day (A 30);
   2. do the same for the temperature of the rooting medium.

What things can be checked less often?

Make regular weekly checks on:

3. Shading - that it still covers adequately the propagation beds (A 33), newly potted cuttings, and those being weaned.
4. Diseases and pests - look out for any signs of rotting, other than shed leaves or damaged cuttings; and insect pests (A 52).

Do the cuttings themselves need checking?

1. occasionally dig up a few cuttings carefully, to check for rooting.
   NOTE: it is best not to disturb the batch unnecessarily;
2. looking at the cuttings can tell you a lot about whether they are thriving or not.

What can go wrong with them?

1. if cuttings shed their leaves - this could mean that they:
   1. had been too wet in the polythene bags;
   2. were overheated in transit, or damaged by chilling injury if too near to ice.
   3. were kept too long before setting;
   4. had been subjected to bright sunlight, drying up or overheating during collection or propagation;
   5. had too little light during propagation;
   6. older, thicker shoots were used, with leaves that would soon have fallen anyway.
2. if the base of the cutting rots -
   1. the rooting medium is (or was) too wet (A 35);
   2. the rooting medium is not well aerated - add more fine gravel, grit or coarse sand;
   3. it is infected with harmful fungi and needs treating with a fungicide (A 52) or changing;
   4. the stem was crushed when the cuttings were prepared - use a sharp blade;
   5. the alcohol was not evaporated off quickly.

3. if a lot of callus forms at the base, but no roots -
   1. try trimming off some callus and replacing the cutting in the bed;
   2. use a rooting auxin, or another auxin, or a different dose;
   3. trim to a smaller leaf size (A 41);
   4. take cuttings from lower on the stockplant;
   5. prune or coppice the stockplant to get more juvenile cuttings (A 6);
   6. shade stockplants (A 33).
4. if the cuttings survive, but don't root -
   as 3 (b – f) and:
   7. consider how to improve the propagation conditions;
   8. try cuttings with different leaf areas (A 41, 45);
   9. take cuttings at another time or growth stage, for example softer (less woody) shoots.
5. if the cuttings go a pale yellowish green colour -
   1. check that the shading is not too great (A 33);
   2. look for signs of pests or diseases (A 52);
   3. improve nutrition of stockplants (A 27);
   (Note that it is normal for leaves to become a bit paler, as they take up little or no mineral nutrients while they are unrooted.)

What else do I need to look out for?

The most difficult things to guard against are occasional, unexpected problems (A 2). Here are some examples - try and think of others; and what you could do about them:

1. breakdown of watering over holiday periods, and through illness;
2. damage from unusual storms;
3. robbery or vandalism;
4. flooding from rise in river level, blocked drains, broken water pipe, tap left on or failure of pump controls;
5. fire damage to wooden framework, shading or buildings;
6. damage to plants or to installations by domestic or wild animals;
7. sudden change in weather conditions.

How can I improve standards of plant handling?

1. By explaining techniques carefully;
2. By checking the quality of work frequently;
3. By arranging work schedules with a bonus for good results, rather than a premium for numbers of cuttings set (A 44).

Do cuttings need a lot of water?

Unrooted leafy cuttings must have high air humidity all the time (A 30, 34), but they will not thrive if the rooting medium is too wet (A 35).

How about when they start rooting?

At this point cuttings can absorb more water from the rooting medium. However, because they are still in a humid environment, the amounts taken up will be small. So you are unlikely to find much drying out of the rooting medium during the regular checks (A 50).

When do cuttings need more water?

After they have been potted up (A 53), particularly while they are being weaned and hardened (A 54).
(Note: during all these stages they need very careful watering.)

How should I water them?

Follow these guide-lines during the critical first 3–6 weeks after potting:

1. check each day whether the soil is beginning to dry up;
2. if it is, water the pot well; if not, leave it till next time;
3. only water the plants that need it;
4. don't ‘drown’ them with excessive amounts of water; but also avoid adding just a little each time, because this may not reach all the soil in the pot;
5. make sure that the water does not run off the leaves and miss the soil;
6. if you see any signs of wilting, and the soil is still moist, don't water! Immediately cover such plants with extra shade, move them to a more humid place or even put them back inside a poly-propagator.
   The problem is not a lack of soil moisture, but rather that the new plant is losing more water from its leaves than it can replace from its still limited root system. (Check that the roots are not being eaten!)

Won't plenty of water make the plants too soft?

No, they need extra care until they have had time to grow a sizeable root system. Once they are well established plants, they can be ‘hardened’ (A 54) in the same way as planting stock raised from seed.

What sort of water is suitable?

The water can come from any source (A 26), provided that it is:

1. clean, and without harmful substances in solution; and
2. at around the same temperature as the new root systems.

Why does the temperature matter?

Young roots are quite delicate, and could easily be damaged by a sudden change of temperature, either hotter or cooler. This is particularly important when the trees have been inoculated with fungi to form mycorrhizas (Manual 3).

What can I do about this?

1. Water early in the day, or late in the afternoon;
2. Watch out for shallow pools and slowly moving streams that may be hot; and springs, wells and rapidly moving mountain rivers that may be cool.

How can I get water at the same temperature as the roots?

Store it in clean 200-litre oil-drums in the propagation area. These should be kept under shade, to stop the water heating up. Fill them immediately after finishing watering, so that the water will have time to cool down or warm up before the next time.

How can I protect cuttings from disease?

The basic answer is to have good:

1. stockplant management and production of cuttings (A 20–27);
2. propagation conditions (A 30–35); and
3. handling (A 41–44) and care (A 50, 51) of cuttings.

But surely diseases could still attack them!

Yes, especially because high humidity tends to favour the spread of disease. However, it is much less likely when cuttings are rooting quickly and well.

How can I tell if disease is starting up?

1. by regular checks on the cuttings (A 50);
2. by looking out for discolouration or blackening of attached leaves or stems - note that it is normal for shed leaves to go black;
3. by occasionally digging out a few cuttings to look at carefully.

What causes disease?

1. Fungi - most kinds of fungus are beneficial (Manual 3), but a few attack weakly or even vigorous plants (for example, root rots and damping-off);
2. Bacteria - again, most sorts of bacterium are harmless or useful, but a few cause diseases such as cankers and wilts;

3. Viruses - these can cause discoloration and distortion of leaves, as in the common leaf mosaic disease of cassava (manioc).

How do they spread?

1. Fungi - by spores, which are present in large numbers in the air, water, soil and on (or occasionally within) seeds; and
   - by hyphae, filaments growing in soil and rotting plant material;
2. Bacteria - large numbers of these occur in air, water and soil;
3. Viruses - these are generally transferred to a plant by plant-sucking bugs, such as aphids, or sometimes by tools. If a virus has attacked a stockplant, it may be present in any of the cuttings taken from it, even if they do not yet show symptoms.

What should I do if I find disease?

Choose the appropriate steps from the following suggestions:

1. remove all dead or dying cuttings and shed leaves promptly;
2. if the disease appears to be localised, remove that part of the rooting medium which may have become contaminated;
3. if it is spreading, spray all the cuttings in that bed with a fungicide like benomyl or sulphur (A 63);
4. before setting the next batch of cuttings, use a drench of benomyl, or put in fresh rooting medium;
5. if disease causes persistent trouble, dip new cuttings briefly in benomyl before setting, or use a rooting auxin containing captan;
6. treat diseased stockplants, and dig out and burn any that remain suspect (if you have some healthy ones of the same clone).
7. avoid contaminating potting mixtures (A 53), and mulch (Manual 5);
8. separate potted plants that are affected from healthy ones; potted plants that are affected from healthy ones;
9. try taking cuttings soon after the shoots have elongated.

What about insect pests?

There are several different kinds, including:

1. Plant-sucking bugs, such as aphids, psyllids, thrips and scale insects, which can weaken the cuttings and/or transfer viruses;
2. Leaf-eating insects, such as caterpillars and grasshoppers, that can defoliate stockplants and also damage the growing shoot tips;

3. Red spider mites, which can damage stockplants and cuttings;
4. Nest-building ants, that could cause problems with stockplants;
5. Wood-eating termites, which can damage propagators and wooden frames;
6. Root-feeding weevils, that live in the soil.

What should I do?

1. clear away material where insect pests may nest and breed.
2. check the underside of leaves regularly for insect pests.
3. where possible, remove the insects when you first see them, or spray with 5 drops of household detergent in 250 ml water.
4. avoid having other host plants nearby. For example, the young stages of Zonocerus variegatus grasshoppers eat ‘Siam weed’ (Chromolaena [Eupatorium] odorata), but later defoliate Triplochiton scleroxylon.
   Some aphids need an alternative host plant to complete their life-cycle.
5. use chemical sprays only when necessary, and not as a routine measure. Choose one that is recommended for the particular pest (A 63), use the dilutions advised, and follow the safety precautions carefully.

Why shouldn't one use pesticides routinely?

1. because they can leave toxic substances behind, which can harm humans and domestic animals. For this reason, some sprays such as dieldrin are no longer recommended for use;
2. because the pests are more likely to develop tolerance to the chemical, which then becomes less effective.
3. because sprays often kill the natural insect predators that keep down the pests.
   (NOTE: biological control is preferable, if methods have been well tested.)

What chemicals are recommended?

There is a huge range of pesticides manufactured. Amongst those that are effective against several different kinds of insects are:
pirimicarb - especially against various kinds of aphids;
dimethoate - against aphids and red spider mites;
nicotine - against thrips, capsids, woolly aphids and some caterpillars.

Are some clones more resistant to diseases and pests?

Judging by other crop plants, this is very likely. If tolerant clones were available in species where the terminal bud is regularly attacked by insects (for instance mahoganies, Chlorophora), this could allow them to be planted much more frequently and successfully.
Finding tolerant or resistant clones can be helped by:

1. Choosing healthy trees (A 12), especially when others nearby have been attacked;
2. Noticing whether stockplants and rooted cuttings of certain clones are frequently or seldom attacked;

At a later stage:

3. Testing clones by actually inoculating them with a known disease, or putting the insect pest on them under controlled conditions;
4. Breeding to combine tolerance with other desirable characters (Manual 2).

How about other pests?

Stockplants and cuttings might be damaged by:

1. nematodes (eelworms) - tiny worm-like animals attacking roots.
2. rodents - close any small holes that might allow mice to get into poly-propagators.
3. birds - shade netting might be used (A 24, 33).
4. antelopes, etc - fencing may be needed, and sometimes pollarding of stockplants (A 21).
5. domestic animals - goats and hens are particularly destructive.

What other protection might be needed?

Don't forget that humans could damage your propagation work, for example by felling trees or collecting poles, burning areas for farming, harvesting leaves for eating and animal fodder, or through vandalism, including removing labels.

What is important about potting up rooted cuttings?

1. It is a critical stage, at which it is easy to lose a lot of plants;
2. It is not difficult, but a sound technique needs to be learnt.

Why is it a critical stage?

Because :

1. the cutting is no longer in air of very high humidity;
2. roots may easily get damaged;
3. the new root system is usually small compared to the shoot;
4. it has to grow into the new soil before it can function well;
5. new leaves may be flushing, increasing the amount of water lost;
6. the leading shoot may be growing, and can easily be broken off.

What sort of soil is suitable for potting?

Occasionally a local source can be used directly. However, it is generally better to mix various materials together, to make a potting soil which:

1. has good aeration, to encourage root growth;
2. has good drainage, but also retains moisture well;
3. contains some organic matter and mineral nutrients;
4. is easy to handle, and does not become hard or sticky;
5. does not contain material infected with pests, diseases or weeds;
6. does contain suitable mycorrhizal fungi (Manual 3), and (in the case of some leguminous tree species) nodulating bacteria.

Why do I need a special potting soil?

1. Because using the nursery soil usually gives poor results;
2. Because a tree in a pot makes greater demands on a limited amount of soil for water, air and nutrients than one rooted in the ground;
3. Because some species will otherwise not thrive (for example Cedrela if drainage is poor);
4. To give better survival and more uniform growth in the nursery (Manual 3);
5. To form a good root system which will help in field establishment (Manual 5).

What can I mix together?

1. Forest top soil - collect in relatively undisturbed forest, especially the surface layer that is a darker colour - good for (c) and (f) above;
2. Black soil from decayed rubbish, but watch out for (e) and broken glass;
3. Coarse sand (0.2–2.0 mm) or grit - especially if you need to improve (a), (b) and (d);
4. Sawdust or shredded bark (well ‘weathered’) - for (b) and (c);
5. Crop residues, such as groundnut shells, rice husks or coconut fibre - for (c);
6. Inoculum for favourable mycorrhizas or nodules, if available - useful (and occasionally essential) for (f) (Manual 3);
7. Fertilisers or trace elements:
   • where there is a particular shortage of nutrients in local materials;
   • when rapid growth is needed;
   • for trees grown for research as pot plants, or in the field;
8. Sub-soil may occasionally be used to bulk up the quality of potting soil, but not if it is clayey, hard or full of stones.

How much of each should I use?

This depends very much on the type of materials available. However, you could start with:- one-third of 1 or 2 above; one-third of 3; one-third of 4 or 5. It is a good plan to try out several contrasting potting mixes, using uniform batches of rooted cuttings or seedlings.
Sieve out any large pieces, and mix the potting soil well, adding water if needed to make it moist enough that it just holds together when squeezed in your hand.
(NOTE: Don't make it too wet!)

When should I pot up cuttings?

When they have at least 2 cm total length of roots, but before any of them get longer than about 4 cm. This stage can be reached in as little as 10 days, but it may take 3 – 6 weeks, and sometimes more.

How can I avoid damaging the roots?

1. By potting up in a moist, shady place, protected from wind;
2. By getting the pots, potting soil, labels, pencil etc, ready first;
3. By digging the cuttings up gently with a small, flat piece of wood;
4. By digging up a few at a time, so they don't dry up;
5. By holding the cutting by the stem, and leaving any rooting medium still attached (Not too deep or too shallow);

6. By putting some of the potting soil into the pot first, before inserting the cutting. Then add some more soil, and firm it down with the fingers without breaking the roots or pulling them off the stem; (This is the most critical stage!)
7. By rooting in bio-degradable containers, which rot away after a few months.
   (Note: don't let them dry out or they may restrict root growth.)
   The rooted cuttings, still in the container, can then be potted on into the normal size of pot without disturbing the root system (A 36).

How can I speed up the work?

1. by training a team to work well together;
2. by making a simple funnel to get the potting soil quickly into polythene pots;
3. by using a bonus scheme based on successful potted cuttings.

Where should I put the pots afterwards?

They need to go straight into shady, humid conditions again. A good place is an empty propagator, or you could make a movable cover lined with polythene sheeting.

But don't they have to get used to ordinary conditions?

Yes, but this needs to be done gradually. If you go too fast, wilting is likely (A 34), which will slow growth, and may damage or kill the young plant. For further details of weaning and hardening see A 54.

Do I water them in?

No, it is much better to use potting soil that is already moist enough, and to rely on high humidity to check evaporation. When the soil is beginning to dry, moderate and careful watering is needed (A 51).

What else is needed?

Write some labels, showing the batch number, and date of potting, and fill in the record sheet (A 67). It is better to go to the trouble of labelling each plant than to get the clones mixed up.

What is weaning?

Gradually accustoming potted cuttings to grow under ordinary nursery conditions.

How is it done?

By decreasing, step by step, the additional humidity (or mist) that is needed for rooting the cuttings.

What's the best way of doing that?

For poly-propagators, you could work out stages such as these:
Stage 1 - newly potted cuttings remain in poly-propagator or under polythene cover;
Stage 2 - covers opened up during the night;
Stage 3 - covers opened up night and day, except in very hot spells;
Stage 4 - weaned plants moved to nursery beds, still under shade;
Stage 5 - reduce the shading (light-demanding species).

How long should each stage be?

Try weaning with one week each for Stages 1 – 3. However, not all tree species react the same, and longer may be needed for stage 1 in hot, dry weather.
If weaning is done too fast, plants may wilt, causing a check to growth and perhaps damage or deaths (see A 34, 51).
If it is done too slowly, the trees may make a lot of very soft new growth, which they cannot maintain with the roots they have.

What about weaning from mist?

The same stages could be given under polythene covers, or alternatively the misting programme could be altered each week to give shorter, less frequent bursts, and no mist at night.

How about weaning from micropropagation?

The plantlets are very small, and have been growing in low light, so they need a longer period to acclimatise to nursery conditions. Follow the suggestions in sheet A5, and don't rush the early stages!

What is hardening?

This is the gradual reduction of shading to accustom the plants to stronger sunlight. It is similar to the hardening of seedling stock before planting, but can take rather longer because the original conditions were very humid.
With shade-bearing species, retain some shade in the nursery, as for seedling plants. Light-demanding trees can be hardened further to grow with little or no shade. New leaves may have to be produced that are adapted to a drier environment.

What is the easiest way of doing this?

If there are only a few rooted cuttings, they can be moved, in several stages, from a very shady place to full sun. If there are large batches, it can be easier to alter the shading progressively:

1. with palm-leaf shade: as the fronds dry, more light will penetrate. Finally thin out the shade, and then remove it entirely;
2. with shade-cloth: use two grades, such as those which cast 60% and 30% shade. Start with both, which gives about 72% shade, then go in turn to 60%, 30% and full sunlight.

How long should hardening take?

If possible, allow about a month for each step, so that more hardened leaves and stem tissue can have time to develop at each stage.

What can go wrong with weaning and hardening?

1. The plants wilt: this could be because:
   1. they should have been watered that morning;
   2. the conditions have been changed too rapidly;
   3. they are growing in an unsuitable potting soil, or were badly potted;
   4. their roots have been damaged by previous drought or waterlogging;
   5. too much fertiliser has been applied;
   6. they have been attacked by a disease or pest (A 52);
   7. weeds have been allowed to grow in the pots, and these are absorbing water rapidly.
   (NOTE: slight mid-day wilting in hot, sunny weather is normal, while in some plants the angle at which leaves or leaflets are held can alter.)
2. Plants stop growing: besides 1(b-f) above, possible reasons include:
   1. their natural growth habit is by repeated flushing and dormancy;
   2. they are shade-bearing species reacting to bright sunlight;
   3. they are short of important nutrients or trace elements (A 27).

What else is important?

Stopping the plants from rooting through into the ground below. This is a common reason for poor field establishment, which originates in the nursery. It happens because:

1. plants often grow better when their roots can explore a greater volume of soil;
2. this makes them more tolerant of poor potting soils and to lax nursery procedures;
3. however, such plants may make rather few fine roots inside the pot;
4. when they are moved, their main roots are broken, and they often wilt irreversibly and die.

How can I stop them rooting through?

1. by using polythene pots with adequate drainage holes in the sides, but not in the bottom;
2. by standing the pots on polythene sheeting (but avoid puddles);
3. by putting them on a concrete surface;
4. by standing them on broken stones, so that emerging roots dry up;
5. by making benching to keep them clear of the ground;
6. by moving them frequently, and breaking or cutting emerging roots.

What else do I need to know about the nursery stage?

1. Information and advice on sources of seed and the growing of seedlings. This is to be the subject of Manual 2 - Raising Seedlings of Tropical Trees;
2. Similarly on the planning and running of tree nurseries, and plant nutrition. This will be covered in Manual 3 - Growing Good Tropical Trees for Planting.

Can I now be sure my cuttings will grow and establish well?

They will definitely have a very good chance of doing so. However, there are still two stages at which all the work could fail in its objective:

1. planning and preparation of the site have to be thought through. This will be examined in Manual 4 - Preparing to Plant Tropical Trees;
2. planting and weeding have to be well done, so that your trees can establish successfully. This will be explored in Manual 5 - Planting and Establishment of Tropical Trees.