Avocados are becoming a very popular backyard tree and, being such a versatile fruit, I’m not surprised.
Persea americana is in the same plant family as cinnamon, camphor and sassafras. Avocados are divided into three races: Mexican, Guatemalan and West Indian. The varieties we grow here in WA are mostly Guatemalan or hybrids of Guatemalan and West Indian.
Hass is the most common variety grown here, making up to 95 per cent of the commercial production. They are grown from Carnarvon down to Albany, with large plantations in Gingin, Busselton, Manjimup and Pemberton.
People think of avocados as tropical trees but some varieties can grow in cold areas where temperatures reach 0C in winter.
Avocado trees are a long-term investment and worth the effort to plant out properly. They are a beautiful tree even without the fruit and require the space to grow to their full potential.Play Video
Rob Broadfield shows us how to split an avocado without any injuries.
0:56 | The West Australian
https://imasdk.googleapis.com/js/core/bridge3.609.1_en.html#goog_1033078698Rob Broadfield shows us how to split an avocado without any injuries.
ONE TREE OR TWO?
One of the main questions regarding growing your own avocados is, do you need two avocado trees?
In order to answer this you must understand the strange flowering behaviour of avocados. They all produce perfect flowers, meaning both the male and female parts of the flower are found on the one flower, but the flower opens and closes twice a day. We divide avocado trees into Group A and Group B.
Group A
When the flower first opens in the morning it is functionally female, ready for fertilisation. Then the flower closes and reopens in the afternoon as a male flower ready to release pollen on to the female parts.
Group A varieties are Rincon, Hazzard, Wurtz, Hass and Reed.
Group B
Group B flowers in the morning as male, releasing pollen then closing. The female flowers open in the afternoon receptive to fertilisation. In a bizarre twist of nature all the flowers on the same tree seem to synchronise and are at the same stage of receptive male or female parts.
Group B varieties are Bacon, Fuerte, Sharwill and Ryan.
Now here’s one for the next quiz night: this process of flowering behaviour is known as protogynous diurnally synchronous dichogamy. Timing is everything.
This is why you are advised to get an avocado tree from group A and group B so there is crossover for the pollinators to flit from staminate to pistillate flowers. You can understand how important pollinators are in this process, which is why growers have beehives in their orchards. Unfortunately, honeybees are not that fussed about avocado flowers but hover bees love them.
After that lengthy explanation, though, I have witnessed many a single backyard avocado tree laden with fruit. Some years will be better than others and much depends on spring weather and how many bees and pollinators are around, but if you only have room for one tree, I suggest you give it a shot. Get a known variety, though; seedling-grown avocados can take up to 15 years to flower.
There are dwarf varieties available, Wurtz and Dwarf Hass. If you only have a small backyard these will do well in a pot and give good quantities of fruit.
PLANTING
The biggest enemy to avocados is heavy soil that doesn’t drain — they will certainly die.
They must be planted in free-draining soil that has had lots of organic matter added at least three weeks before planting out.
They hate hot and cold winds so find somewhere protected that receives full sun. Compost, manure, rockdust, wetting agent, cocopeat, biochar, fish heads, anything you can throw in the hole.
Dig the hole at least 60cm deep and 1m wide, making sure the hole is well watered before planting. Don’t fiddle with the root system because they don’t like it. Always spread a good thick layer of mulch about 15cm deep but keep it well away from the trunk.
Avocado trees transpire a lot in summer so they require lots of water, especially in spring when they flower.
Avocados are highly susceptible to sunburn, particularly when young, so put a shade-cloth tent around them or paint the trunk and branches with white acrylic paint. Use an anti-transpirant spray such as DroughtShield at the beginning of November and liquid potassium as a foliar spray in December.
Fertilising is important for fruit production and should be applied at the beginning of every season.
Trace elements are vital so use a good-quality, slow-release fertiliser such as Grow Safe with the added soil microbes to help protect your avocado from Phytophthora cinnamomi.
DISEASES
The two major diseases that affect avocado trees are dieback (Phytophthora cinnamomi.) and anthracnose (Colletotrichum gloeosporioides).
Phytophthora affects the root system of trees and gradually kills the tree. Symptoms are yellowing leaves, drooping, leaf drop, branches dying back and bark peeling off. Tree injection using phosphorous acid is recommended when the tree is actively putting on new growth and temperatures are above 25C.
Anthracnose is the major post-harvest disease, particularly in Fuerte and Wurtz avocados. Symptoms are seen on the fruit, leaves and stems with small black spots developing, becoming larger as the fruit develops. Spray trees with liquid copper sprays or copper hydroxide during warm, wet weather.
CAN YOU GROW AVOCADO FROM ITS SEED?
Most gardeners would know that avocados are so easy to grow from seed. However, I suggest you only use these as root stock to graft a known variety on to.
They can take at least 8-10 years to bear fruit and it may not be all that good.
They will probably always fruit eventually but is it worth the wait?
