I guess you could describe avocado as one of the least economical fruits in the vegies section of the supermarket. But it sure is a healthy meal all in one nicely rolled inside a swag of leathery peel with such a large seed that dominates the fruit and leaves us feeling we have all been robbed by Coles et al.
The simple truth is that avocados are a tough nut to crack in the garden and perhaps the truth behind that lies in the enormous challenges that face growing them. They revel in the warmth of Queensland but struggle in the famine and feast of rainfall. Too much and our root enemy Mr Phytophthora gate crashes the party, or too little and it melts like an ice cream in the hands of a welder. So how is that 65% of Australia’s fruit comes from Queensland and what are the keys to that success?
Avocado production in Australia is as rich with history as avocadoes are with healthy oils. The main varieties were imported in the 1930s, and since then commercial avocado production in Australia has gone from strength to strength. There are now over a thousand growers in Australia which produce a total of 46,000 tonnes of avocados a year. The key commercial growing areas include north, central and south east Queensland, northern and central New South Wales. The diversity of Australia’s environment, along with the rise of the selected varieties gives fruit supply to markets on a year-round basis.
Being an evergreen subtropical fruit tree native to Central America and Mexico, 65% of avocado production in Australia comes from Queensland. Warm temperatures however, are far from the complete package with commercial avocado production. High yields of avocados are dependent upon successful flora initiation, floral development, pollination and fruit set. There is clear evidence that avocados must be insect pollinated, and the fruit set appears to be better when the varieties are interplanted.
Being of a sub-tropical origin, avocado trees are frost susceptible, particularly when young, so are best suited to frost free locations such as Queensland. But further evidence suggests that it is the temperature and rainfall that has a marked effect on honeybee activity. Bee activity is very limited below a temperature of 13°C. Bees visiting blooms tend to decrease along with the distance they tend to travel from the hive below 13. With the distance and the bees able to travel in mind, the use of bee tubes in place of the hives is producing promising results and proving to be a cheap option to the use of full hives.
The avocado tree comes into its flowering flush in spring, when the flowers are borne on the current year’s growth. There are two varieties of avocado which is crucial to the process of fertilisation. With the type A, the female organs are receptive to pollen in the morning with the pollen released later in the day. The type B is the opposite way around. Therefore, although avocados are considered to be self-fertile it is crucial that both types are therefore interplanted to ensure cross pollination and higher fruit production.
Avocado trees do not grow true to type from seed, so they must be grafted onto root stocks. The main commercial variety in Australia and much of the world is Hass. This variety has a generally accepted flavour and has proven to be reliable cropper in a wide range of climatic conditions.
Much of the recent work with avocadoes has been in the use of dwarf root stocks. This has lead not only to easier handling, training and growing within the increasingly smaller gardens with what is a traditionally large tree. The smaller cultivars has also led to easier management, pruning and spraying.
As with all fruit crops, pest management is fundamental to their success. Vermin, scale, thrips and fruit fly possess the greatest pest threat with Phytophthora cinnamomi being the major disease challenge to the crop.
With evidence showing that the numbers of bees within the crop canopy playing such a fundamental part in high fertilisation rates with avocados, that IPM (Integrated Pest Management) early on in the season is an increasingly complex but fundamental management technique to keep unwanted pests away but the bee colony numbers thriving.
As most of us don’t particularly want to don the full bee keeping gear and face playing the part of Winnie the Pooh and his pot of bee soaked honey, perhaps if you are keen on getting the avocado to flourish and have that salad complete with the sliver of green, then it’s time to bring in the bees and get planting those Brachyscome, Callistemon, Eucalyptus, Grevilleas and Hibbertia scandens, to name but a few bee magnets.