Tree Friend Avocado (PERSEA AMERICANA)
An evergreen tree about 3- 6m high x 3-5m wide with large, dark green leaves and green to dark, fleshy, oval fruit.
The avocado (Persea americana), from the family Lauraceae (Myrtle).
Varieties in Australia
The most common varieties in Australia are: Type A – Gwen, Hass, Lamb Hass, Pinkerton, Reed, Rincon, Secondo and Wurtz. Type B – Bacon, Edranol, Fuerte, Llanos Hass, Ryan, Sharwil, Shepard and Zutano
Best varieties to grow in Perth
Type A: Hass, Lamb Hass (smaller Hass variety – about 3-4m instead of 5-9m) Type B: Sharwill and Wurtz (3m). Other suitable varieties Reed(A) Feurte (B), and Bacon (B).
Average expected life of the tree
An avocado tree will continue to grow and produce fruit until something kills the tree. If healthy, 50-400 years
Years until first fruit
Seedling trees take up to 8 years to fruit. However grafted trees can produce fruit in 2-4 years.
2-year-old trees, which are usually about 2m high, can provide a yield of up to 40 fruits if planted in a good aspect with well-prepared soil. Fully grown trees can produce between 500-1000 fruits per year depending on variety.
Most productive season/s In Perth, avocados usually flower on new growth in early spring, form the fruit in late spring and are harvested from June until November, depending on the variety.
Expected or average number of years the tree is expected to fruit
The original Hass tree (1926) produced fruit until it died from root rot and was cut down in 2002 at the age of 76. There are reportedly wild trees in Mexico that are over 400 years old that are still producing.
Country/area of Origin
Central and South America. 50% of the world’s avocados are grown in Uruapan, Mexico
Average rainfall in area of origin
Uruapan has average rainfall of 1625 mm which occurs mainly in its summer months from June to October with winter being moderately dry.
The ideal pH for avocados is between 5.5 and 7, although the trees can tolerate slightly more acid or alkaline. They enjoy similar conditions to citrus.
Generally, avocados are self-fertile but yields will increase if an A variety and a B variety are planted to allow pollination overlap. Type A avocado flowers are ready to be pollinated in the morning, but any blossoms flowering in the afternoon are releasing their pollen. Type B, therefore, release pollen in the morning and are ready for fertilising in the afternoon.
Shelter and positioning
Avocados prefer a sunny position sheltered from hot drying winds, particularly the easterlies. Their tap root systems are shallow and spreading so If the tree is to be let grow to more than 4m high, do not plant too close to buildings or pathways. Avocados need some shade in summer for the first couple of summers or at least until they have grown their full leaf canopy which largely occurs when they are about 2m high.
Avocados are adaptable. They may be espaliered if preferred (2.5m apart is ideal, less if dwarf varieties are grown) and the smaller cultivars (Lamb Hass, Wurtz) may be grown in pots. They make a great windbreak when planted close to each other. For shade, plant in the west or south west of the property and allow it to grow into a large tree.
An annual rainfall between800 -1200 mm is desirable. Perth has an average rainfall of 850 mm. The trees are shallow rooted and have poor water uptake. Drip line irrigation or bubblers are ideal for avocados, with some hand watering if necessary in very hot weather in Summer. Over irrigating can lead to root rot. If the tree’s root system is fully saturated for 48 hours it will die.
Mulch is critical for avocado trees. It retains moisture, slowly feeds the tree, encourages soil biota and protects the soil from extreme temperatures. Ideally, in August, mulch with a thin layer of compost, then a layer of Lucerne and top with aged recycled tree prunings. A depth of 60- 75mm in total for all layers is ideal.
Products, benefits, useful/ interesting facts
Avocados are used mainly as a food however are also used to make oil, soap, shampoo and skin care products.
An Australian woodworker has reported that it is suitable for carving, resembles White Beech (Eucalyptus kirtonii); is easy to work, and dresses and polishes beautifully. He has made jewellery boxes.
Avocado came from the Nahuatl (Aztec) word “ahuácatl” which means “testicle. It is also referred to as alligator pear.
Avocados will not ripen while they are still attached to the tree, apparently because of an inhibitor in the fruit stem.
Height, width and shape of tree at maturity
Avocados are attractive evergreen trees which usually grow in a cyclical manner between 3- 6m high x 3-5m wide in metro Perth.
Trunk: 30-60 cm in diameter.
Fruit: Large berry. Yellow-green or reddish brown, large, usually pear-shaped, sometimes ovoid or globose, 70-200 mm; exocarp corky; mesocarp fleshy and edible. Weighs 100-1,000 grams with a single large central see
Foliage: Avocado leaves are alternate, glossy, elliptic to obovate-oblong, 10–30 cm long, 4–10 cm wide, leathery, upper surface dark green, lower surface glaucous and sparsely hairy; secondary veins prominent, reticulum coarsely areolate; petiole 2–7 cm long. They normally remain on the tree for 2 to 3 years
Flowers: Although the trees produce an abundance of flowers, usually less than 0.1% of the flowers set fruit and most of these fruits abscise within 6 weeks from full bloom. Avocado flowers are inconspicuous and appear in terminal panicles of 200 – 300 small yellow-green blooms. Each panicle will produce only one to three fruits.
Harvesting: Avocados will naturally grow into large trees, which can make harvesting difficult. It is advisable to prune the tree when young to create a low branching structure which is easy to climb on to collect the fruit. Best to prune them back to 2-3m picking height each year.
Challenges or special requirements
Root rot (Phytophthora cinnamomi) can develop fairly quickly in poorly-drained soils. It is therefore essential to determine in advance the suitability of the soil for avocado production. The tree’s primary requirement is good drainage. It cannot stand excessive soil moisture or even temporary water-logging.
Scale, aphids and thrips can also attack avocados.
Anthracnose is another fungal disease affecting avocados. It appears as small black spots on the foliage which spread out and cover the leaf, drying out the leaf which then falls off. It can also spread to the fruit causing fruit drop.
Avocado leaves, bark, skin, or pit are documented to be harmful to animals. Cats, dogs, cattle, goats, rabbits, rats, guinea pigs, birds, fish, and horses can be severely harmed or even killed when they consume them. The avocado fruit is poisonous to some birds.
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