There are several books on plant propagation available from Libraries and Bookshops, however these are generally for English or American conditions and species. Practical courses on Plant Propagation are conducted by the Rural Youth Community Extension Service at Clare and Gatton Colleges.
Grafting is a form of vegetative or asexual propagation, used generally only when other forms of propagation cannot be satisfactorily used.
Grafting is the art of joining parts of plants together in such a manner that they will unite and continue their growth as one plant.
Because it is labour intensive, commercial nurseries tend to use it when it is absolutely necessary - navel oranges and some avocados, and I know of no local nursery which uses grafting. They find it more economical to buy in grafted plants.
Before you attempt any grafting, read whatever material you can get. Get your equipment together. Prepare your rootstocks and scions. Then practise making your cuts on similar material to what you will be using. All cuts must be neat, flat and even, as any pockets or depressions could mean a source of infection.
Remember, you must have a very sharp instrument for grafting, so take extreme care to make your cuts properly and pull the wood through the knife. The knife can be lethal if not used correctly.
PARTS OF GRAFT:
In all types of grafting or budding, there are two essential parts:
The Rootstock or Base
and Bud Scion or Top.
Rootstocks are generally strong and healthy seedlings, while the scion is selected from healthy mature plants or trees which are true to type and have produced good fruit.
The main difference between grafting and budding is that in grafting, the scion can consist of from 1-4 buds, whilst in budding, only one bud is used per union.
Budding is therefore advantageous where limited material is available. There are many forms of grafting and several of budding; some have particular application, whilst some applicators vary their methods to suit their purpose the best.
Some species can be propagated by any of the methods of sexual or asexual propagation, Leucaena being a classic example. It is normally grown from seed, but can be grown from woody or tip cuttings, airlayers, buds or grafts.
In grafting, the first consideration must be that there is an advantage in creating the new plant by grafting. Then we must know if the rootstock and scion are compatible. You have to experiment, but generally plants of the same genera are compatible with varying degrees in sub-families and families. e. g. Tomatoes and Potatoes will graft easily, while Acacias and Leucaena are not compatible, even though they both belong to the family Leguminosae.
We can be guided to a degree by the commercial operator: e.g. Bush Lemon as rootstock for Citrus and Briar Rose as rootstock for most Roses, or we can experiment with a variety of combinations, which should be tried with a variety of methods at varying seasons.
Don't ever give up after a failure - go back and check everything and see if you can improve anywhere.
Preparation: Whether grown in the field or in pots, rootstocks must be growing well and have free-flowing sap. They must be healthy and disease-free, as a failure can as often be the result of poorly prepared rootstock as poor techniques.
SCIONS or BUDS:
Scions should, where possible, be selected with dormant, but near bursting, buds, and again be healthy and disease-free. They should be dipped in suitable fungicide, if available, to stop or reduce virus and fungal attack. However, selection of clean material, the use of sterilized equipment and general hygiene and good techniques should suffice.
When taking scion material from the parent plant, convenient lengths can be taken and the leaves, but not the leaf petioles, removed. These petioles protect the new buds during transport and grafting.
In making a graft or union, the operator must match the cambial layer or cambium of both scion and stock, as this is the only area where the union is made by callousing. The better the combination, the better the graft.
In budding, the bark of the rootstock must lift freely to allow the bud to be inserted without damage.
Scions or bud material are best used as soon as possible after collection, however where there is a delay, the material should be placed in a sealed plastic bag and kept in a cool, preferably dark, place.
The operator needs a good pair of secateurs that leave a good, clean, neat cut with a minimum of bruised material; a clean, sharp knife, scalpel or razor blade; and some form of keeping it sharp; something in which to sterilize your implements - a bottle of metho; some form of tape or strips of clean plastic to bind the graft; and a label on which should be recorded identity of stock and scion and possibly date done and type of graft.
Where a grafting knife is not available - and the only difference, really, is that a grafting knife is bevelled on one edge - a scalpel or razor can be used.
Once the plant is grafted, it should be given special care. It must be kept out of the wind and is best kept out of direct sunlight, or covered by a paper bag.
Freshly-grafted plants should be watered carefully, as under- or over- watering will cause problems. Never apply water above the graft, as water-borne fungi kill grafts.
Nutrients can be given, as long as this is done carefully.
DATE: March 1983
* * * * * * * * * * * * *