Luke has had an interesting career as a school chaplain and pastor, and latterly as president of the Yarra Valley Bee Group and cultivator of heritage fruit trees. Main points of his talk:
Horticulturalists may increase plants either by sexual reproduction (pollination and seed formation) or asexual reproduction (grafting, cutting, layering, division, bedding and tissue culture). The advantages of sexual reproduction are that it is quick, economical and easy, but produces offspring that are genetically diverse, i.e. not necessarily true to the parent. Asexual methods produce clones of the parent plant but are generally more labour-intensive.
Grafting is the joining together of the cambium (growing) layers of the scion (top of the plant) and the rootstock. This gives the possibility of combining the best attributes of two different, but genetically related, plants to produce a superior new plant. It is particularly suitable for fruit trees and has been the means of retaining certain heritage varieties which might otherwise be lost because they are of no commercial value. It has also been useful for the home gardener in enabling the one tree to produce a variety of fruits that ripen at different times, thus extending the harvest season and reducing the need for cold storage and/or transport.
There are a number of different grafting methods using different complementary shapes for joining together the the scion and the rootstock when the two are of comparable size: wedge, splice, whip-and-tongue, and approach grafting; less common and used when the scion is significantly smaller than the rootstock are cleft, side, notch and bark inlay grafting. Budding is a similar technique except that a bud is used instead of the scion.
Tools needed: grafting knife, grafting tape, wax, Clonex rooting hormone (used in very dilute solution to stimulate cell growth).
Plants must be related to each other (same genus or same family);
Tools must be disinfected to avoid transferring any diseases such as apple mosaic virus;
Plant samples are usually best collected during dormancy;
Drying out of plant parts can be prevented by using ziplock bags for collecting them;
Graftable plants include maples and fruit trees such as apples, quinces, plums etc.
There will be a grafting workshop at ECOSS next July, run by Neil Barraclough.
Reference: Dave Wilson in Nursery Educational Video series.
Ancient Greek proverb –
A society grows great when old men plant trees, whose shade they will never sit in.