Citrus: sweet and sour by Malcolm W. Campbell BA, MAIH, MIPPS.

Although many of our citrus cultivars have originally been imported from the Middle East or the United States, we have an enormous variety that have been bred locally from bud sports that have appeared on imported cultivars, so that now most of the Australian crop is the result of such a sport or chance branch. A sport that produces a better fruit than the original parent plant will soon show up and be budded by keen orchardists until it has proven itself. Such is the case with the 'Seedless Valencia', which was identified at Richmond NSW in the early 1920's as a superior and almost seedless form of the popular, but seeded variety 'Valencia'. The 'Red Navel' orange is also the result of a bud sport taken from the 'Washington Navel', at Mundubbera Qld. The 'Red Navel' is almost seedless and its rich colour makes it popular with home gardeners. The juice keeping qualities of the 'Washington Navel' is only a few days in the fridge, which is what makes 'Valencia' the world's favourite, because it keeps for much longer.

When selecting citrus for your region, be persuaded by what local experience tells you about particular cultivars. While the period of fruit set might seem important, it's far more important to select cultivars and varieties that will tolerate your soil type, your weather, rainfall or quality of reticulated water, distance from the coast and amount of winter sunshine. Most retail nurseries, supermarkets and garden centres secure their citrus stock from local wholesalers since the varieties and the rootstocks they are budded onto, are often quite specific to your region. Plant quarantine on citrus is so stringent in some states that importing plants beyond your local area is quite difficult or prohibited altogether in South Australia for example. The propagators have an Elite Budwood Scheme in citrus growing states, where newly imported buds or local selections that are certified virus free buds are distributed to three citrus propagators in each state, who then bud them onto their local rootstocks to trial for several years before releasing some of them. Most citrus for home gardeners are budded then grown for two years before selling them as sturdy container-grown citrus plants. Citrus are not easily grown as open rooted plants like the deciduous fruit and nut trees, since they often put on growth during the cool season as well as the fact that some rootstocks resent root disturbance. They also take two years to become sturdy enough and for the bud union to mature on the rootstock, that's why you seldom see small citrus in 140mm pots. As for the rootstocks which propagators use, that's probably of no interest to anyone other than the commercial growers. The home gardener should be aware that there are rootstocks that are well suited to clay and alkaline soils and there are those that thrive on acid soils. There are also special rootstocks for dwarf varieties and that there is also a considerable degree of rejection if a scion was to be budded onto a no-compatible rootstock, but that really is far too specialised for this text. Best advice is to buy your citrus locally and that will have already been considered.

Citrus nomenclature, is used fairly casually by some growers and retail outlets, so that you will encounter some common names abbreviated and other regularly misspelt. I've used the synonyms where there is obvious confusion, such as with 'Honey Marcott' (syn. 'Marcott' & 'Marcot'), but some retail nurseries also use a local promotional name that is not tregistered cultivar. I have not used these names, because they only add to the confussion and should be discouraged. The range of natural selections used by propagatators, further clouds this simplicity a bit. If you are aroused to seek more information, approach your local citrus marketing body or citrus nursery person, I've found then to be most willing. Their names are listed under "Acknowledgements" at the front of this publication.

When reading the descriptions of the cultivars you can take it as understood that all citrus will grow to 4 metres tall and as wide, have thorns on their stems, and seeds in their fruits, unless stated to be otherwise.