Common Name: Avocado.
Etymology: Persea: sacred fruit-bearing tree of Egypt and Persia (probably originally related to a pear). americana: from America.
History: The avocado dates back almost 10,000 years with the oldest archaeological evidence (a cave in Coxcatlán) suggesting it originated in Puebla, Mexico. Fossil evidence also suggests that (millions of years ago) similar species occurred as far north as California when the climate there was more hospitable for them. The native undomesticated species (known as a ‘criollo’) is small with dark brown skin and contains a large seed and is probably similar to what the ancient people of the time were collecting and consuming after minimal processing. It is thought, that at this time, they may have started selecting larger fruits that eventually lead to what we see today. The avocado has a long history of cultivation in Central and South America dating back some 5000 years and wide spread distribution followed the Spanish conquest. The earliest account of the avocado in Europe was in a book by Martin Fernandez de Enciso in 1519, it was introduced to Indonesia in 1750, Brazil in 1809, South Africa and Australia in the 1800’s and the Levant in 1908. Today, the avocado is among the most traded tropical fruits in the world with its major producer being Mexico. The common name ‘avocado’ comes from the Aztec word ‘ahuacatl’ which meant both ‘fruit of the avocado tree’ and ‘testicles’ (yes I can see the resemblance). The early Spanish thought that ‘ahuacatl’ sounded similar to their word for lawyer ‘abogado’. Later the English changed it to ‘avogato’ pear and then alligator pear. It all gets a little confusing from here on. Interestingly enough the Aztec word for guacamole is ‘ahuacamolli’.
10 Uses of Avocado: The avocado is a powerful antioxidant and contains a range of vitamins and nutrients needed for a healthy body. It is high in folate, Vitamin C, Vitamin E and is a good source of potassium. Avocados are rich in fibre and healthy fats while naturally low in sugar and sodium.
- Can be used in an endless variety of recipes either as an ingredient or on its own. Cooked, mashed, frozen or whole.
- Drinks, smoothies and daiquiris.
- Excellent alternative to oil, butter and cheese, swapping bad fats for good and for those watching their weight healthy fats also help release hormones in the intestine which can signal fullness, controlling appetite.
- Face moisturizer.
- Foot scrub.
- Hair treatment.
- Seeds can be used as a tea to ease stomach ache, cut and applied to teeth to reduce tooth ache, for massage and decoration.
- Shaving cream.
- Sunsceen. Avocado oil has a high proportion of mono-saturated fats that form a protective layer over the skin (SPF 4-15).
Basic description: Fast growing, dense, evergreen tree, usually to 9m but can grow up to 20m. Although evergreen it does shed leaves briefly in the dry season at blooming time. Trunk is 30-60cm in diameter, greater in older trees branches form a broad tree. Leaves are dark green and glossy on the top and whitish underneath varying from lanceolate to obovate (7.5-40cm). Small, pale-green or yellow-green flowers are borne profusely in racemes near the branch tips. Fruit is pear-shaped to round, 7-20cm long, dark purple (almost black) to green, and can weigh between 100g-1kg with a large central seed. Avocados are classified into 2 flowering types, type A (ready for pollination in the morning, releasing pollen in the afternoon) and type B (ready for pollination in the afternoon, releasing pollen in the morning). The fruit of avocados do not ripen on tree but start to ripen once picked.
Avocado requirements & maintenance: pH 6-6.5 (acid – slightly acid), warm, sunny, sheltered position with particular attention paid to free draining soils as trees will not survive in wet conditions (48 hours submerged and the tree will die), in fact most of the trees disease problems are associated directly with too much water. In saying this, however, the root system is shallow so a regular watering routine will be required over the hot summer months particularly when young (they are sensitive to saline water if irrigating). Avocados are more of a tropical fruit but will survive in cooler climates (as low as -4 in mature trees for short periods) provided the soil conditions are right and tree is protected from high winds. Mulch well with rotted material ensuring no contact with trunk.
Harvesting time: This varies dramatically depending on the variety and climate but generally speaking it is time to harvest when the first couple fall from the tree.
- Comfrey (trap crop for slugs, soil improver).
Problem Solving without chemicals:
- Anthracnose: Fungus that lives in dead twigs, leaves and fruit and spread through the warmer months from splashing water. It causes small, light brown, circular spots that quickly get bigger and darker, centres of these becoming slightly sunken. It becomes active when fruit is damaged or when it ripens. Prune out dead twigs and remove effected fruit from the tree. Leaf spot does not generally require treatment.
- Bacterial soft rot: A bacteria common in both soil and on plant surface usually causing problems in damp conditions. The fruit has a darkened metallic sheen externally and internally is grey to black and soft with a putrid smell. There is no treatment for effected crop (organic or chemical). Discard damaged fruit, do not harvest fruit in wet weather, try not to damage fruit and follow good hygiene practices.
- Banana spotting bug: Bug elongated in shape about 15mm long (very similar to fruit-spotting bug but a slightly lighter green). Sap sucking causes water-soaked area from which sap exudes and drys white later with narrow cracks around them. Fruit is damaged to about 15mm. Avoid planting trees close to native bushland. Assassin bugs and spiders prey on bug.
- Boron deficiency: Leaf dieback, scorching and dead areas. Leaves may develop too close together. Distorted yellowing and dying twigs. Cracked, rough fruit. Boron governs the flow of glucose from chloroplast to roots (feeding microorganisms in the soil) who in return send essential nutrients via the roots back to the plant. Soil may be too alkaline locking out Boron or sandy causing it to be flushed out. Use Borax at 2g per square meter (do not overdo borax as plants only require tiny amount.
- Fruit-spotting bug: Australian native green-brown bug about 15mm long with prominent antennae that when disturbed will fly away or somersault to lower branches or quickly hide behind fruit and under leaves. Eggs are 1.7mm long, pale green and somewhat triangular. Both adults and nymphs feed by piercing fruit and sucking the juice from the tissue. They insert their long mouthparts into the fruit and in feeding, exude saliva containing enzymes that break down the cells of avocado and causes hard lumps or stones under the skin. This causes deep-set breakdown of significant areas of tissue. Avoid planting trees close to native bushland. Assassin bugs and spiders prey on bug.
- Fruit fly: In summer (particularly wet and humid weather) flies lay their eggs in small groups just beneath the skin, larvae make their way to centre of the avocado and destroy it. Affected avocados are easy to recognize as skin around the sting marks becomes discoloured. Fruit will be full of maggots and inedible. Burn and destroy all fruit or seal fruit in plastic bag and leave in the sun for several days. The ‘Cera Trap’ and ‘Eco-Naturalure are new and effective organic fruit fly baits. Adults lay eggs (‘sting’) in the fruit and the larvae feed in the flesh.
- Phytophthora root rot: Pathogen in wet soils that rots roots causing yellowing and dieback of plant from the tips. It is spread in water through chemical stimulus as well as root-generated electric fields. Add compost to soil (stimulates competition also ammonia and volatile organic acids released by decomposing organic matter kill Phytophthora), improve drainage.
- Red-shouldered leaf beetle: Australian native beetle, 6mm long, yellow with red band top of wing cover. Rapid skeletonization of foliage. Hard to control, beetles can be knocked into bucket of soapy water on small plants. In larger plots Eucalyptus torelliana (as a windbreak) is highly attractive to these beetles and is useful for early detection and control.
- Scale: Small black, brown, pink or white insects that have either a hard or soft outer shell and attach themselves (usually) to underside of leaves (in veins) and along branches. Use White-oil at recommended dose on bottle, control ants that also help spread them.
- Stem end rot: Fungus that lives on any dead twigs and leaves on the plant, spores are splashed about during wet weather. Fungus remains dormant until fruit is mature and begins to ripen. Prune out dead twigs and remove effected fruit from the tree. Control irrigation.
- Sun-blotch: Symptoms include pink, white or yellow leaf variegation, yellow streaks on bark and yellow or red streaks on fruit, also fruit can be small and tree low yielding. There is no cure known cure and other plants can be effected. Remove and destroy plant and ensure future virus free stock is purchased.
- Swarming leaf beetles: Small 3-5mm shiny brown/black insects that swarm after first heavy rain causing sever damage to terminal growth of plant causing retardation. Eucalyptus torelliana is a favoured host for this beetle.
- Zinc deficiency: A yellowing between the veins of new leaves, veins may turn yellow particularly at the tips. Zinc can be added as a trace element in a foliar spray or as part of a kelp solution spray. Soil maybe too alkaline.
Growing avocados: Listed below are some of the popular varieties for growing in Australia:
- Bacon – (type B) 9m tall, harvest Jun-Jul ,most cold tolerant down to -8 degrees Celsius, unlike other varieties fruit will fall from tree when ripe.
- Edranol – (type B), harvest Aug-Sep
- Fuerte – (type B) 10-12m tall, cold tolerant, harvest Jun-Oct every second year, does require deep, well-drained soil in excess of 4-5m which together with their height may be a disadvantage in backyards.
- Hass – (type A) 10m tall, Sep-Jan harvest, does require deep, well-drained soil in excess of 4-5m which together with their height may be a disadvantage in backyards.
- Pinkerton – (type A) harvest Jun-Aug, warm temperate to sub-tropical, large quantities of fruit.
- Reed – (type A) 4m tall, harvest Nov-Mar.
- Rincon – (type A) 4m tall, Jul-Sep harvest, warm temperate to sub-tropical.
- Sharwil – (type B) 10-12m tall, Jun-Aug harvest, sub-tropical to tropical, does require deep, well-drained soil in excess of 4-5m which together with their height maybe a disadvantage in backyards.
- Wurtz – Type A, 2.5-3m tall, compact tree, warm temperate to sub-tropical, harvest Oct-Dec, will not tolerate the cold.
Many of the large varieties are also grown on dwarf root stock and shouldn’t exceed 2.5m making them suitable to smaller gardens.
- What Garden Pest and Disease is That by Judy McMaugh.