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Most plants can be propagated from cuttings however, some plants are quite difficult to persuade to grow roots, whilst others may take an inordinate length of time (years) to “strike”. Do not let such problems, either real or imagined, prevent you from trying. Propagating mix: Generally, sand, or vermiculite, or a mix of the two will be satisfactory. Even compost and/or composted wood-chips have been used with success.

Soft-Tip Cuttings: Usually taken in Spring. Very few fruit trees are propagated by this method, but generally anything in the Solanum group, such as Pepinos and Tamarillos will be fine. Take a reasonably substantial length (normally not less than 10cm) from the growing tip of the branch [twig]. Make the cut directly below a growth-bud. Remove all but the very top leaves, and reduce the size of the leaves which are left on, this reduces evaporation-loss of liquid from your cutting. Plant your cuttings in the propagating-mix to ¾ of its length. A rooting-hormone powder may be used, but is generally not necessary. Do not allow the propagating mix to dry out, and mist over the cuttings daily. Some method of supplying bottom-heat would be an advantage, such as sitting the container with the cuttings in the top of a hot-working compost heap. The cuttings may be potted-up as soon as the roots appear, often after only 3 weeks. Problems: Fungal infections resulting from the moist, humid conditions may require treatment with a fungicide.

Semi-Mature (Tip) Cuttings: Usually taken in Autumn. Citrus, Feijoa, and other evergreens can be propagated by this method. Note that many Citrus are prone  to soil-born diseases, and therefore only resistant varieties such as Poncirus trifoliata and citrange should be propagated by cuttings, usually for use as rootstocks. Take a reasonably substantial length (normally not less than 10cm) from the tip of a branch [twig] that has ceased its seasonal growth but is still green and soft. Make the cut directly below a growth-bud, or, if the propagating-wood is short enough, tear it off the main branch, leaving a “heel” of older wood attached. Remove all but the very top leaves, and reduce the size of those leaves, to reduce evaporation. Plant the cutting in the propagating mix to ¾ of its length. Do not allow the propagating mix to dry out. Some method of supplying bottom-heat is frequently an advantage. Commercial growers often heat the benches upon which the cutting trays are placed. The little plants should be rooted and ready to pot-up in Spring. Problems: Fungal infections are the worst danger, but watch out for snails and slugs.

Hardwood (Mature) Cuttings:  Usually taken in late Autumn or Winter. Deciduous fruit-trees can usually be grown by this method, but evergreens are also worth trying. Take a substantial length (normally not less than 15 cms long, or less than ½ cm thick). Make a slanting cut just above the terminal growth-bud, just as if you were pruning. Make a horizontal cut immediately below the bottom growth-bud on the cutting. Now you know which way is up, and you won’t plant the cutting upside-down! Remove any leaves. A slight vertical slit in the bottom of the cutting may increase the callous (rooting) area. Plant the cutting in the potting-mix to at least ¾ of its length (some propagators only leave the top bud above the surface). Rooting-hormone is generally a waste of money for hardwood cuttings. Do not allow the propagating mix to dry out. Some form of bottom-heat may help things along. The plants should be ready to pot-up by the following Winter. Some plants can take a very long time to produce roots: just put them back in and wait for another year!

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The green sapote (Pouteria viride) tree grows very well in the Brisbane area as long as the soil is well drained. In marginal areas it is, like the avocado, very prone to root rot. The tree is an attractive one similar to the mamey sapote, but smaller. It originates from volcanic, mountainous regions of Central America, which is very well drained.

I recommend planting grafted of marcotted trees only in ideal conditions, otherwise plant seedlings. Hill the soil well if its condition is poor, or not well drained, this way the tree will survive quite wet conditions. Green sapotes can be grafted on mamey sapote rootstock; it can handle wet conditions much better. My experience has shown me that the tree may survive wet periods more successfully, but will drop its fruit in very wet weather. After planting, put a few rocks or concrete slabs on the north side of the newly planted trees, cover the ground and rocks with black plastic, and the tree will grow even in the winter as the ground temperature will be up to 5 deg. C warmer. Green sapote trees will not take more than the lightest of frosts.

I also graft green sapote trees on green sapote seedlings, or marcot them. The grafted and air-layered trees bear fruit in 3-5 years; quicker than trees grown from seed, which bear in 5-7 years. The casualty rate is higher in marcotted trees, this is easy to understand, given their natural habitat in Central America.

They flower in late spring or early summer. The fruit takes 12 months to ripen. Fruit that ripens in spring is not nearly as sweet as summer fruit. Cold weather or too much at flowering can affect fruit set. As the flowering season is quite extended the trees are mostly heavily laden with fruit.

The fruit weighs 200-500 gr. It is green in appearance, turning yellow when ripe. It is delicious eaten fresh out of hand, blended with milk, or served with ice cream. My experience has shown me it is not as popular as mamey sapotes with my Central American customers, and appeals more to Asian and European tastes. Its flavour is milder than the mamey sapote’s, and somewhat sweeter. Its flesh is lighter orange-red, compared to mamey’s deeper red. This suggests to me that green sapote is more suitable for eating fresh, mamey for cooking. My son Peter, who works in the hotel industry, puts a small amount of vanilla or coffee essence in the smoothies he makes, to enhance the flavour, and says both the mamey and green sapotes are fantastic in milk drinks or with ice cream.

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• Also see article titled “Grafting Workshop”
• Custard Apple – take the centre out of your custard apples trees.
• Chester recommends Howe Longans as they have big fruit and the tree is dwarf.
• Grafting Black Sapote you need wood that’s been hardened off – don’t use the soft new growth – October. The variety Bernacher is more upright but you get a lot of seconds and it is also bat prone! Maher is more rounded but is susceptible to splitting. The fruit is on the tree for a year.
• Autumn Bliss and Heritage Raspberry – AB is a late season and Heritage is early but AB has better flavour
• Mango – recommended are late season varieties:  Keitt, Palmer, Brooks and they fruit in that order.

compiled by Sheryl Backhouse
 

Authored by: 

Sourced from: 

STFC newsletter Feb Mar 2008

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Synonym(s)

Myrobalanus catappa;   Terminalia badamia;  Terminalia mauritiana; Terminalia moluccana; Terminalia myrobalana

Family:

Combretaceae (combretum)   According to the World Agroforestry Centre, the tree is native to Australia, Cambodia, India, Japan, Laos, Malaysia, Thailand and Vietnam.

Common names:

Indian almond, Sea Almond, Beach Almond, Story Tree, Tropical Almond, Wild Almond

I grew up in Bowen, a small town on the Whitsunday coast. Indian Almonds or Sea Almonds as we called them, grew along the beaches, in the parks and in our yards. I have eaten the raw nuts since I was eight years old and for years thought they were the same nuts found commercially packaged at the supermarket as they look and taste the same. The fruits are almond-shaped and green turning brown to purple when ripe. The fruit surrounding the kernel is (apparently) also edible but I haven’t tried it, nor would I like to. About 18 years ago I found myself in Kuranda (north Queensland) without access to food. My friend (from Adelaide) and I had caught the train so were without transport. It was a public holiday and the shops were closed. We thought we were destined for starvation until we noticed an Indian Almond tree towering over the other trees in the rainforest, some distance from the road.  We made our way through the bush and found hundreds of nuts on the ground near the base of the tree. We used a large rock to remove the nuts from the husks (fruit) and we lived on those nuts (and water) for the next two days. The tree has since been a favourite of mine. My mother has (8) 32 year old Indian Almond Trees growing in her yard. When she first moved into the house they were the only plant that survived the beach conditions. They provided mulch which allowed other plants to survive. She now grows ferns, begonias and a magnolia underneath them. She had a sewerage line put in two years ago. The pipe was to pass one trunk no more than 4ft away. The workers told her they did not come across one root. She believes the trees have a very deep tap root and says they are very stable in a cyclone. About 7-8 years ago I asked her for three seedlings. She didn’t think they would survive well at my place in Brisbane as they normally grow in sand and I have shale.

Growing conditions

“The species grows in greatest concentration on sands and loamy sands”. They are “also found on silts, loam, and clays. Soil pH is usually neutral to moderately alkaline and rich in bases. However it will also grow in strongly acid soils. Good drainage is required on clay soils” [www.worldagroforestry.org]. I have seen them growing beside running creeks with their roots in the water. Most of the literature states that it does best in full sun, moist, well drained soil and that it is salt and drought tolerant.  It is not however frost tolerant. The trees biophysical limits are “Altitude: 0-800 m, Mean annual temperature: 15-35 deg. C, Mean annual rainfall: 750-3 000 mm” [www.worldagroforestry.org]. Two of the three trees I planted here in Brisbane survive to this day. They are known to be fast growers (in excess of 1 metre pa) however mine did not appear to grow until six years after being planted out.  Last year they trebled in size. The largest is now about two metres high, a far cry from the 15 – 30 metres they can grow to in ideal conditions. The good news is I have seen specimens that have been kept in pots for years looking beautiful and healthy. Recently my mother visited me and she brought with her eight seedlings and seven seeds. I mentioned to Sheryl that I planned to donate six of seedlings to the club and as a result she asked me to write this article.

Uses:

Food: the kernel is eaten raw (apparently unlike commercial almonds) or roasted and used to “extractable edible oil used for cooking” [www.worldagroforestry.org]. Flavonoids present are “quercetin and kamferol.” [www.tropilab.com/terminalia-cat.html]

Fodder: “The foliage is used as a feed for silkworms and other animal feeds” [www.worldagroforestry.org] including ornamental fish food [www.tropilab.com/terminalia-cat.html]

Timber: “The tree provides a red, good-quality, elastic, cross-grained timber that seasons well and works easily.” “It is strong and pliable and is used for the construction of buildings, boats, bridges,floors, boxes, crates, planks, carts, wheelbarrows, barrels and water troughs” [www.worldagroforestry.org].

Erosion control: “The tree’s vast root system binds together both sands and poor soils” [www.worldagroforestry.org].

Soil improver: “A good provider of mulch for the protection of soil and young crops.” [www.worldagroforestry.org].

Gum or resin: “The trunk is a source of gum” [www.worldagroforestry.org].

Tannin: “Bark, leaves, roots and fruit are all important sources of tannin with the astringent bark containing 9-23% tannin. The outer shell is also rich in tannin.” [www.worldagroforestry.org]. “The tannins contained in the leaf are  s. a. punicalin, punicalagin and tercatein” [www.tropilab.com/terminalia-cat.html].

Dyes: “The trunk is a source of yellow and black dye; it is used in leather preparation and as a base for inks; sometimes the roots and fruits are used for the same purposes” [www.worldagroforestry.org].

Medicinal: I don’t recommend you treat yourself with the tree products for the following disorders or afflictions, rather I feel it is better for you to see your doctor.

a) Liver related diseases: “In Taiwan the fallen leaves of [the] tropical almond are used as a herbal drug in the treatment of liver related diseases” [www.tropilab.com/terminalia-cat.html]. The American Journal of Chinese Medicine [An International Journal of Comparative Medicine East and West], Vol. 25, No. 2 (1997) 153-161 describes experiments carried out in relation to the trees efficacy in treating liver problems in rats. “The results apparently indicated that T. catappa possesses

good antihepatotoxic activity and superoxide radical scavenger activity” [www.tropilab.com/terminalia-cat.html]

The following medicinal uses have been taken from the following sites: [www.worldagroforestry.org] [www.tropilab.com/terminalia-cat.html]

b) Astringent: the leaves and fruit

c) Dysentery: Suriname’s traditional medicine used against dysentery and diarrhoea is a tea from the leaves.

d) Vermifuge: red leaves

e) Leprosy: young leaves, cooked with oil from the kernel

f) Bilious fever, diarrhoea, thrush, and as a remedy for sores and abscesses: bark and roots

g) Headaches: young leaves

h) Colic: young leaves

i) Chemo-prevention of cancer: (this in my mind is always suspect as it may indicate it is cytotoxic. Cancer cells and hair follicle cells etc can be more readily killed by poisons because being fast growing they have high metabolism and therefore take in more toxin than normal cells).

j) Anticlastogenic effect: (i.e. reduces chromosome breakage)

Description:

Some sources describe the tree as “pagoda-like” in that it has tiers of several horizontal branches. The bark is grey-brown. The trunk can be up to 1.5 m in diameter. The trees I have seen in rainforests are often buttressed at the base however those I’ve seen growing on the beaches don’t seem to be. I could be wrong about this though. The leaves are obovate, approximately 30 cm long and turn hot pink- red to orange and yellow before falling. The leaves can fall off a number of times in a year. I’ve noticed mine defoliate during dry spells. Regeneration occurs after being watered. The male and female flowers are inconspicuous, found on the same tree and are greenish white in colour.

Propagation Methods

“The ratio of male to hermaphroditic (female) florets is 16:1.” “Various insects (Coleoptera, Diptera, Hemiptera, Hymenoptera and Lepidoptera) pollinate the flowers” [www.worldagroforestry.org]. “Pollination is not [however] required” [www.tropilab.com/terminalia-cat.html]. The fruit are eaten and the seeds distributed by fruit bats and birds. The seeds float and can be carried considerable distances on the oceans and still remain viable” [www.worldagroforestry.org]. “Seeds for planting are generally gathered beneath mature trees. A suggested pre-treatment is soaking seed in cold water for 24 hours. Germination of the seeds is epigeous. About 70% of ripe seed germinate in about 20 days.”

“Seeds should be set 25 x 25 cm apart in nursery beds. Transplanting to the field is done during the next rainy season.” [www.worldagroforestry.org].

Pests and diseases

Terminalia catappa is said to be susceptible to defoliating insects, especially when young. Grasshoppers and beetles are apparently especially troublesome in Malaysia. Thrips and the West Indian termite Cryptotermes brevis are known problems and the thermophilic fungus Paecilomyces varioti is said to cause die-back of T. catappa seedlings. [www.worldagroforestry.org/Sites/TreeDBS/Botanic] My Terminalias have not had any of the above mentioned problems. Recently, when my other plants were being eaten to bits, my Terminalias remained untouched.

Tree management

Before planting, fertilizer should be applied to poor soils. Although the seedlings develop slowly at first, growth soon accelerates. Weeding is necessary for a few months after planting, but there is soon sufficient cover to shade out competition. It will coppice as a seedling or sapling, but the species is not a strong sprouter. The species is known to form natural root grafts and has natural pruning characteristics. [www.worldagroforestry.org/Sites/TreeDBS/Botanic]

Related readings

Available on request as there are too many to mention or refer to the www.

“Bush Tucker Field Guide” by Les Hidden

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 On our property on the upper slopes (300m ASL) of Mt Tamborine, we are blessed with great views, minimum temperatures of only plus 8 (no frost) and a northerly aspect on sloping land that traps a lot of heat and sun. The soils are rich, black and volcanic in nature with a major presence of highly weathered basalt, overlaid by some clay and alluvial soil. Drainage is good once roots get below the thin clay layer. While this all sounds perfect, rainfall has not been perfect by any stretch of the imagination and this has been exacerbated by the northerly exposure with strong winds. Keeping soil wet is a major challenge, especially for newly planted trees. We have planted over 500 trees over the last 8 months, and even with a bore and plenty of water, we still ran into problems. The main issue is water repellancy of the soil once it has dried out. All the books I have read talk about the wonders of compost, sheet mulching with paper to suppress weeds, the joys of deep layers of mulch and many other topics related to the soil nutrition and pH. I am yet to see an article on soil that has dried out and the resulting water repellence problem. So here is my experience and my solution as applies to planting new trees in the sub tropics.

The soil it would seem gets much hotter and much drier than the average garden in Melbourne and Sydney. As a result, some of the practices suitable for conditions down south appear less suitable here in SEQ. The rainfall in SEQ tends to be more concentrated in the summer months with a considerable period of little soaking rain during the dry. This situation was worsened this year (2001/2002) with very little summer rain to date. As a result soils have dried out and irrigation does not alleviate the problem.

When we planted most of our trees, we planted the trees into the best commercially available “organic soil” into a shallow hole. The soil had poultry manure applied and was then covered with wet layers of paper to suppress the weeds with an area around the trunk of the tree to allow water to penetrate. The whole area was covered by a thick layer of forest mulch to depth of 20 cm at least. Liberal quantities of water were applied before the paper was laid and after the mulch layer. We watered religiously for the first 4 weeks and then a sprinkler irrigation system once a fortnight. It was at this time that we notices trees were becoming stressed. The problem became obvious after a simple examination of the root area of the trees. The problems with the system we used are listed below:

• The ‘organic soil’ used did not hold water very well because the organic content was too low;
• The soil applied to the roots was in many cases already water repellent and all the water we applied was shed and thus did not solve the problem;
• The paper had dried out and become an impenetrable water repellent barrier, so all water applied over the mulch was shed. The paper didn’t break down, although in direct contact with the manure, because it was not wet;
• In many cases, the trees were planted above the level of the surrounding ground for extra drainage and this did not allow the water to pool so that the soil, paper and mulch could not soak up the water;
• The sprinkler irrigation system allowed water to penetrate into the soil around the plant, but the “organic soil” did not wick it up because it was water repellent.

 We have now changed our system of planting to overcome the problems listed above:

• The soil used for planting (all soil really) should be kept moist and under a tarpaulin until used;
• The organic content of commercially available soils needs to be increased with compost or other organic matter. We buy soils by the truck load, specify that enriched compost be added and mixed in before delivery;
• Water crystals are always added to the soil at planting time. We apply a wetting agent to the soil, in addition to the water crystals during planting and no paper is used over the planting hole;
• We hand water for 8 weeks after planting and never, never let the soil dry out during this period;
• We plant in spring and summer now so that we catch the increased rainfall and also allows more cold sensitive plants to become established before the colder months.

If you are in the unfortunate position of having water repellent soils around your plants the only solution is to physically agitate the soil with a jet of water. Simply sprinkling the surface of the soil will NOT work no matter how long you water. The water jet method works well, but you do need to be careful that you do not damage the roots of the plant. Applying a wetting agent before you break the water repellency does not work either. Wetting agents can be applied after you have solved the problem, then the wetting agent helps to keep the problem under control.       Happy Gardening

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Joe says you can induce seedless fruit on pummelo by spraying with GA3 (Gibberellic Acid) when the plant is at 50% bloom. He wrote to not spray before bloom because that would prevent blooming.  Before the bloom opens, there are reproductive buds, or unopened flower buds that are pyramidal shaped and about 1 to 2 mm diameter. If you spray GA3 at that stage, they will revert back into vegetative buds, thus you prevent blooming. 

Technically, you minimize blooming when you spray GA3. Because of non-uniformity of statistical distribution of stages of bloom, a few of the flower buds would be at the point of no-return and wouldn’t revert back to vegetative stage, but there is a stage of the unopened flower bud that can revert back into vegetative buds when sprayed with GA3. During 50% bloom, I meant that approximately 50% of the flowers have opened and are receptive for pollination.

We know that this is a population of distribution of stages of flowers, numbering in the hundred thousands or millions within a canopy, and for sure they don’t have the same phenostage, and you would have various stages from unopened flower buds to petal fall, but approximately 50% of them are open and are receptive for pollination. When the flowers have opened and they are sprayed with GA3, the flower is tricked into reacting that it has been pollinated and so the fruit would set without forming any seeds, and thus we have seedless fruit.

This has been observed with watermelons, and other fruits.  Again, it is not 100% seedlessness because of the population distribution of the stages of flower, and some of them have already been pollinated before the application of GA3 but majority of the fruits would be seedless, to those that were receptive but have not been pollinated and received a whiff of GA3, and then you would have tremendous fruit sets that are seedless. 

Because you would have tremendous fruit set, you may need to spend extra labour to thin out the crop but that depends on your flower density, and so you may have to apply GA3 either at 25% open blooms or even at 10% but this depends on flower density. If you have few flowers, the 50% bloom would be the best time, but if you have a tremendous amount of flowers, you may need to spray during the 10% bloom. Some of the blooms would revert back, depending on the stage of the flower, but those that are open and are receptive for pollination would have fruit set that are seedless when sprayed with GA3. You can search for the references about GA3 application in citruses on how to control the alternate year bearing in Clementines.

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At our most enjoyable field trip, I heard our most kind host say that his roses were no good to talk about, as they were not edible so I thought I should mention that indeed they were.
Two parts of the rose are edible: the hips and the petals. The hip (fruiting body or berry) is in Northern Europe a well known gift of autumn, picked from briar roses. During the war years, school classes were let loose over the ‘commons’ and forest lands on school outings, though no doubt many hips were picked too green, for you need a lot of them to make cooking worthwhile. They were greatly valued for their vitamin C content, though how much of the vitamin survived the cooking process is questionable. Anyway, the jam tasted nice.

I remember having the time consuming task under my grandmother’s supervision of cutting the fresh hips open and scooping out the seeds and the hairy fluff surrounding them, leaving the exocarp and fleshy layer 2-3mm thick. Later I acquired a wonderful attachment for my hand mincing machine which squeezed the pulp of the boiled fruit through a cone of sieve holes and pushed out the pips and hair at the front end. This does not yield quite as much pulp, but it makes the job a lot easier.

The lovely hybrid tea roses of our Australian gardens are not normally suitable for producing hips. They stay green, the edible layer is too thin, and the hips are produced over most of the year, so there are never enough at any one time to make harvesting worth-while. Besides, most roses are pruned or have their fruit removed to conserve their strength for producing more flowers. Old-fashioned shrubs flowering once a year are more suitable, as buds open all at once.

Some roses, mainly Rosa Rugosa, a deciduous shrub species, have been grown in the Netherlands and northern Germany along roadsides expressly for their hips. They have single white to dark red flowers in early summer, mostly large, with a delicious perfume and a particularly high vitamin C content in their large hips. In times when citrus fruit was scarce or unavailable , they were highly prized. Rose-hip syrup is still sold in health shops to give to infants, but is rather expensive.

Now to the glorious edible petals. Most rose varieties are selected for long flowering seasons and for keeping well in vases, but what is worth saving is the fragrance. Without a really good old-fashioned damask fragrance, rose petals are of no use, for when boiled they are rather tough to chew. To make a good jam with them, you need to use enough apples to give it body.

Cordial  I have used petals to make rose syrup as a cordial, using this recipe: fill a very large bowl with petals of fragrant, preferably red roses, and pour hot water over them, just covering them. Cover the bowl with a cloth, let it stand for a day to extract the fragrance and colour, and then pour the liquid into a big pot, squeezing out the petals and discarding them. Add an equal weight of sugar and, if you like, a little citric acid powder to taste. Boil up the mixture and pour into bottles with airtight screw tops to overflowing, screwing the tops down tightly. If you don’t care for the slightly bitter flavour, twist the petals all together off the stem end of the flower and cut off the white section at the base of the petals with scissors before soaking them. I have also found that rose petals with a little citric acid and plenty of sugar and gelatine make a nice dessert jelly. It’s best to add the rose petals freshly chopped, after the gelatine has cooked slightly.

Roses prefer a cold winter, preferably heavy soils, and/or constant attention. “Papa Meilland” seems to do quite well in Brisbane clay soils. In sandy soil where I live, nearly all rose cultivars deteriorate after one or two years. Only the particularly strong-growing “American Home” (bred by Boerner in the USA in the late 50s and 60s) survives long without spraying. Unfortunately it does not seem to be on the market anymore. Half a dozen plants of this cultivar would supply all the petals needed for a few bottles of syrup or wine in several flushes of perfect flowers a year.

Editor’s note: Helga supplied numerous recipes for using roses and a list of types of roses most suited to using in cooking – here is one recipe, for rose petal jam. 

Rose Petal Jam  500g strongly scented rose petals, (red or pink are best), 2 cups pure apple juice, 1.5kilo sugar, juice of 1 lemon. Cut off white heels off rose petals because these become bitter in cooking. Combine rose petals and apple juice, bring to boil, strain liquid and reserve petals. Return liquid to pan, add sugar, stir until dissolved, add lemon juice, and rose petals, continue cooking over heat until mixture gels. Pour into sterilised jars, seal with paraffin wax.

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1. Highest possible profitability 2. Earliest fruit production and $ returns 3. Highest possible yield per hectare 4. Consistent reliable yield every year 5. Long lived orchard 20-30 years 6. High quality fruit of desired size 7 Easy management – pruning, thinning, spraying, harvesting etc. 8. Able to physically protect crop as required    frost, hail, birds etc.

9. Able to grow desired crop on marginal soil types

The above can be achieved if we: a) Select the correct variety to suit the climate and market b) Use proper cultural management techniques c) Select the correct rootstock – not necessarily dwarfing d) Limit tree size to a maximum height of 4-6m

e) Use correct canopy management techniques

Limiting Tree Size and Maintaining Regular Cropping

Smaller trees will obviously produce less fruit per tree than larger trees. It is therefore necessary to plant smaller trees closer together to achieve the highest yield possible per hectare. There is well documented research that high density, deciduous and citrus orchards with more easily managed small trees will make better use of sunlight and as a result will consistently produce higher yields collectively per unit area than wide spaced orchards in the long term.

The difficulty in the past has been to manipulate and control naturally tall growing subtropical fruit trees by timely pruning and managing the canopy to discourage strong summer growth while still producing enough growth to produce heavy crops. These trees must produce new growth each year to develop and mature the existing crop and at the same time produce extra food reserves in stems and branches for next year’s crop.

Recent research in the past 5-10 years has resulted in a better understanding of tree growth cycles or phonological cycles to enable timely tree manipulation to control tree growth and size and to know what to do when. Subtropical fruit growers that do not have an established culture of timely pruning may have difficulty in coming to terms with canopy management. Mangoes and Lychee that have a simple, clear 12 month flowering, fruiting, harvest, growth and dormancy cycle are much easier to manipulate than Avocados. Avocados can have a simple cycle when fruit mature before flowering in warm subtropical areas. However the late maturing Hass variety when grown in cool to cold areas mature fruit so late that often growing cycles overlap and flowers and/or young new season fruit are competing for 2-3 months before the previous season’s fruit is harvested. The result is often biennial bearing with an acceptable crop only being harvested every second year. New varieties should be planted in cool areas that not only mature
fruit later but flower later so seasons don’t overlap to enable easier canopy management procedures and regular annual cropping.

Controlling Tree Size using Canopy Management Techniques

1. Promoting Heavy Early Bearing

The best way to slow tree growth and contain tree size is to promote heavy early bearing. Once trees are well-established 4-6 months from planting, tree complexity must be rapidly increased to develop as quickly as possible as many horizontal fruiting laterals that have fruiting potential. By carrying out ‘controlled leader pruning’, the young tree is still able to grow upright while still producing laterals for fruiting. Good levels of well balanced nutrients must be applied to promote, strong growth and heavy fruiting.

2. Promote and Develop Multi Leader Growth Habit

This is important for when trees reach maximum height when we need to implement major limb removal to reduce tree complexity and keep the orchard ‘young’ to ensure new growth is produced each year and fruit size is maintained. The development of multi leaders happens with little effort as all trees will do this as part of their natural growth habit. The number of leaders that naturally develop is dependant on tree spacing that determines light availability.

3. Maintain Desired Tree Shape

This should start as early as possible after tree establishment and strong growth commences. Most unpruned stand alone trees have a natural growth habit. Some grow upright and some spread out. Almost all subtropical fruit cultivars will grow more or less in a pyramid shape until fruiting occurs. Heavy fruiting has the effect of weighing down branches and shading the branches below. During this period summer growth develops into the open spaces where light is now plentiful to once again to be weighed down next year. Lower branches that become continually shaded by higher branches soon die out due to lack of sunlight. The long term result is that of an inverted pyramid shape wider at the top and narrow at the bottom with fruit being produced higher and higher up the tree as lower branches die out

By selectively pruning back vigorous terminal shoots higher up in the tree at the correct time of year ensures less fruit is produced higher up, lower branches are maintained through good light exposure and produce more fruit down low. A ‘narrow pyramid’ shape or ‘tent shape’ should be selected to suit the growth habit of each specific fruit cultivar and pruned at the correct time of year. The correct time of the year to selectively head back or tip prune strong high growth back to tip prune strong high growth back to laterals is 3-4 months prior to cold weather or ‘dormancy’ to limit regrowth time but still allow mature enough growth to develop and properly flower and set a good crop. Heavy late pruning may result ‘m growth that is too immature to set fruit in spite of flowering due to insufficient food reserves. Heavy or too frequent early pruning of the spring growth flush will encourage excessive stronger summer growth that will require more regular selective hand pruning during summer.

4. How and When to Prune

Suggested recommendations are listed in detail in crop canopy management calendars. Avocados are light pruned during the latter stages of the spring flush but mostly in midsummer 3-4 weeks after the main summer flush commences. Provided trees have been pruned back to the desired shape from year 2, little fruit will be removed as it will be back inside the outer tree canopy. Pruning back summer flush allows light into the tree and encourages the development of fruiting wood within the inner framework.

Mangoes and Lychee are basically outside tip pruned back to the desired tree shape, and size immediately after harvest to bring the entire tree, into a uniform regrowth cycle in late summer.

5. Major Limb Removal (window pruning)

This is carried out in early flowering to partially rejuvenate the tree by selectively removing a major vertical upright limb to make the tree less complex from year 5-6 onwards. A maximum of 15-20% of total tree only should be removed otherwise excessive vegetative growth and fruit drop may result during the following late spring/early summer growth flush. Any excessive vegetative growth must be selectively pruned as necessary. However removing the correct amount of major limb during winter should result in low vigour growth coming back evenly over the entire tree after fruit set with the spring growth flush, and some watershoot development regrowing with the summer flush. Repeated major limb removal means some watershoots  must be allowed to regrow to eventually replace major limbs during summer.

6. Restricting Root Development in Fertile Soils as an Aid to Canopy Management

Controlling tree growth in highly fertile soils in hot subtropical climates can be difficult. In Mexico, Florida and South Africa, various methods are employed to restrict root development, that in turn aid in canopy management and strong vegetative growth control. In hot dry areas, controlling irrigation and water distribution effectively restricts root system development and coupled with fertigation, gives the desired result.

Deep ripping, an essential part of land preparation for any fruit tree planting, in particular Avocados, can be a very effective means of restricting root development. By only ripping with a single ripper down to 0.5m or by double tynes 30cm apart down to only 30cm in very fertile volcanic soils works well. Conversely in shallow soils or poorly aerated infertile soils, deep ripping preplant on a 0.5 metre cross grid to a depth of lm+ can mean the difference between successful rapid establishment of young trees or slow, erratic growth and poor long term productivity.

7. Natural Restrictive Root Development Effect of Shallow Soils

In Florida, solid ‘coral’ deposits are machine trenched along the row and across the row. Trenches are approx. lm wide and lm deep. Trees are planted where trenches cross. The result is trees can only grow to a certain size as they are virtually growing in ‘a pot’ with highly restricted root area and regular rejuvenation pruning must be carried out to produce new growth and corresponding fruit production.

This same principle applies with most soils that have ‘a bottom’ or an impervious clay, sandstone or rock ‘C’ horizon 1-2-3m below ground level and explains why so many unpruned subtropical fruit orchards become non-productive after a given period of time depending on available soil depth.

Canopy management practices are easier to apply in shallow soils that aid in the control of tree size when trees reach a maximum size relevant to soil depth.

Summary of recommendations

1. Increase complexity of small trees for heavy early fruiting 2. Promote and develop multi leader growth habit for future major limb removal after year 5-6 3. Maintaining desired tree shape from year 2 4. How and when to prune – crop canopy management calendars 5. Major limb removal

6. Restricting soil preparation and root development as an aid to canopy management

Conclusions

Growers planting permanent high density orchards must look closely at the overall concept and implement the total canopy management package to achieve success. Varietal selection, planting density, row direction, correct soil preparation, well balanced nutrition both pre and post planting, and application of correct pruning techniques at the correct time all must fit together to achieve success.

Long term canopy management systems operating in high density orchards in Israel and Florida and more recent research being carried out in South Africa indicates that success can be achieved. Systems and methods employed in manipulating high density orchards must be easily understood and easy to do for industry to adopt them as a standard practice. It is hoped this paper has addressed some of these issues to give growers the confidence to venture into canopy management of high density subtropical fruit orchards Avocado, Lychee and Mango.

References

Stassen, P.l.C. and Davie, S.J. (1996). Principles of a Tree Management Programme. Institute for Tropical and Subtropical Crops Information Bulletin No. 285. Goren, M. and Gazit, S. (1992). Small-Statured Litchi Orchards; A New Approach to the Growing of Litchi. ACTA Hort.349:69-72. Middleton,S.G. (1996). Theoretical/Practical Design of Orchards – Proceedings of the 4’h National Lychee Seminar, Australia, pp 24-29 Wolstenholine, B.N. and Whiley, A-W. (1996). Strategies for Maximising Avocado Productivity – A Review. World Avocado Conference III Israel.

Snijder, B. and Stassen, P.J.C. Manipulation of Hass Avocado Trees – Pruning – A Progress Report. South African Avocado Growers Association Yearbook, pp 73-76.

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Australian tropical fruit orchards are traditionally grown on flat or slightly undulating land. This is primarily because of the costs of harvesting and tree management – a large expense given our high labour costs. In Thailand however, their good flat agricultural land is used for rice and vegetable production and the hillsides are reserved for fruit tree orchards. Obviously the low labour costs make this possible. Khun Pradoldej Kalayanamit, the largest lychee grower in Thailand with 8 lychee orchards, is also a mango, tangerine and strawberry grower. He told me he pays his workers 75 baht a day (about A$3.10) for a dawn to dusk workday and has about 10 full time workers per farm. The all year round jobs such as slashing, spraying, watering and pruning are all then done by hand at little expense to the grower.

Watering

I observed several methods of watering in Thai orchards. Several lychee farms, as well as some mango and longan orchards I inspected, dug a shallow pit around each tree on the drip line, which was then filled with water by buckets. Other orchardists in the Thaton / Fang area whose trees are often grown on 50 degree slopes, pump water to the top of the slope and simply let the water run down the hill. Many of the more affluent orchardists used under tree irrigation, but used tall aluminium stand pipes (2 – 3 m) to spray high up in the tree. They claimed this spread the water further and also added humidity to the air at the important ripening time, when fruit can dehydrate quickly, if not watered sufficiently. All farmers watered regularly but in small volumes. While most agreed to my way of thinking that water application was most important during early fruit set when cell division and development were taking place and again on colouring of the fruit, few seemed to use practices to take this into account. The bucket brigade watered “when the soil dried out” and I had little faith in flooding from the top of the hill. However the farmers with a regulated and controlled system (under tree irrigation) most often explained they watered for one hour every three days. Couple this with an 80 litre per hour microjet, and each tree only got about 200 litres per week! I regularly give my trees between 750 – 1000 litres per week, but in one single application, increasing this to 1500 litres per week during the rapid fruit enlargement just prior to harvest. Tests carried out in Australia several years ago indicated that water stress on bearing lychee trees had little bearing until the last 4 weeks before harvest, when fruit failed to develop to any size, and a lot of fruit was dropped by the stressed tree. As this does not seem to be a common problem to the Thai growers, there must be some other factors at work in Thai orchards. Further investigation is warranted on this apparent inconsistency.

Fertilising

As is the case in Australian orchards, fertilising of lychee trees was dependent very much on the soil types on which the trees were growing and the weather and rainfall statistics for the area. To grow trees successfully, free draining and not overly rich soils were needed, so that the supply of water and nutrients could be more or less controlled, especially in the all important pre-flowering time. All Thai farmers used a complete N-P-K fertiliser, with the most common one observed being a 15-15-15 mix. Application time was late March – early April when fruit was at pea size, with the rate being 1 kg per metre of tree height. Most farmers also used a foliar spray once a week for 3 weeks before panicle emergence. These rates were increased significantly for the few growers with orchards on the flat land, especially if they were on river flats.

While the use of fertigation is becoming increasingly popular in Australian orchards, I only saw one instance of this practice in Thailand. This was at the huge Boonrawd orchard near Chiang Rai in Northern Thailand. Owned by a major brewery in Thailand, money was not a limiting factor, so that recently sourced overseas technology was rapidly integrated into the whole farming enterprise. Here a 10-52-17 mix at 2500 parts per million was applied in two applications totalling 3kg. The first application was made just before the rainy season and the second during the rain. It was interesting to note the poor crop on these trees, which the owners attributed to the adverse weather conditions. My own experience however, would suggest that applying fertiliser both before and during periods of heavy rain would be counter productive, with the fertiliser being washed away or carried so far down into the sub-soils as to be unavailable to the shallow rooted lychee trees.

In summary then, Thai farmers operated under a similar belief to Australian growers, that is you fertilise to produce bigger and better fruit, rather than bigger trees. Fertilising both before and after fruit set is now widely practised in both countries, in the expectation that after harvest when trees are nearly drained in regard to available nutrients, the wet weather will result in only one or at the most two post harvest flushes, so that trees are kept smaller and in a fruiting rather than flushing state.

The use of organic fertilisers, though only practised by a small number of farmers at present, is, according to one grower I spoke to in Lamphun in Chiang Mai province, increasing rapidly. He uses a system called EM (essential micro-organisms) that he buys in from Japan. The make up of this liquid is kept secret by the Japanese, but is claimed to be a mix of soil health promoting organisms that replace the need for any fertiliser application. This product is mixed in to rice husks, animal manure and whatever other biodegradable product is available, has molasses poured over it and is then left for three days covered with hessian bags. There was obviously some reaction taking place, as this mixture was very warm to the touch, even though it was in the shade of a large shed. This is then used as fertiliser at the rate of 10kg per tree 3 times a year. Neem oil mixed with the EM is also used as an insecticide whenever necessary. The farmer claimed he produced the biggest and best fruit in his area and was rapidly convincing more and more of his fellow growers to switch to his methods. Unfortunately I could not see any of his fruit because he had already completed his harvest and neither could I see his trees as his paddock was too wet! Perhaps some follow up visits may be appropriate when I am next in that area.

Flowering induction

In Australia at present, getting trees to flower regularly and heavily takes up most discussion whenever lychee growers get together. This is especially a problem on the hotter and wetter coastal regions, rather than on the cooler Tablelands region where I grow these delicious fruit. Flower induction is brought about by a combination of two factors – the point of growth of the tree and the weather. The first of these we can try to control, the second we cannot. The ultimate is to have your trees just starting a new growth cycle as the cold weather starts. This means having buds around the 1-3 mm size with the arrival of cold weather (< 15 degrees C) during the night, and in the low 20’s during the day. Buds bigger than 3mm will result in either all new growth or a mixture of leaf and flower and if the trees are not in a growth cycle and are dormant, they will likely stay dormant until the warmer weather arrives again and then be vegetative. Farmers in Thailand have similar problems and have developed several methods to ensure they have good flowering at least 9 years out of 10. These are cincturing, the use of potassium phosphate and the use of potassium chlorate, calcium chlorate or sodium chlorate. This method requires further investigation in the warmer growing areas of Queensland where flowering can often be irregular. Initial attempts at this practice have proved unsuccessful in Queensland in the one large scale trial that was conducted. However on talking to the grower involved in this, I believe the timing, so critical in this exercise, was not correct. While not being necessary on my own farm where I can more easily control growth, such a process needs to be revisited on coastal orchards in Northern and Southern Queensland. Already several growers in these areas to whom I have spoken, or who saw the process themselves when I took a group of growers to Thailand in May, 1999, have decided to put the process into practise on small areas of their own orchards for evaluation.

Depending on tree vigour and water availability, lychee trees can continue growth cycles well after the desired one or two flushes following the post harvest wet season. This dramatically increases the chances of trees being in a growth or hardening off stage with the onset of colder weather, resulting in little or no flowering. This was a particularly bad problem in the Chiang Rai province of Thailand.

Cincturing and Potassium Phosphate

This is a method also practised in Vietnam and China, where trees are ‘ringbarked’ to stop all vegetative growth. Each tree in an orchard has a narrow cut made around each branch after the tree has divided into the 4 – 6 branch stage. This cut must be very precise as far as depth is concerned, because if it is too shallow nothing is achieved and too deep and the branch dies. This is why individual branches and not the whole trunk is cinctured – better to lose one branch rather than the whole tree. The cut must go down to the cambium layer and no deeper. This has the effect of stopping the trees growth, with all its energy put into repairing the damaged section. Once this repair has been made, the tree switches back into a growth cycle. The Thai farmers, with assistance from their agricultural advisers, have found that if they cincture their trees in October each year, the exact date depending on their area, the trees will take around two months to repair themselves and then start a new growth cycle just in time for the new Thai winter, so that flower initiation occurs in January. Chiang Rai Horticultural Research Station set out to find an easy solution for growers of large orchards where cincturing was not realistic.

Researchers there have found the use of the chemical potassium phosphate goes a long way to solving this problem. The chemical is applied through a misting machine at 5000 parts per million at 7 day intervals for 2 or 3 times, about 6 weeks before anticipated cold weather (and flowering). This has the effect of hardening off any flush on the trees in only 2 or 3 weeks, much shorter than the normal 5 – 6 weeks and putting the trees into a dormancy stage – exactly what you want. Then with careful manipulation of water, you can induce flowering at the right time. A fellow lychee grower in Sarina has already put this process into effect on his own property, because when he arrived home from Thailand with me, he found his trees covered in a brilliant flush. He immediately applied potassium phosphate, the flush hardened off quickly and his trees are now flowering well. The process seems to work well and further research is needed into its causes and long term effects. Growers now have some hope of generating flowering on trees that are overly vigorous at the wrong times in the year, trees, which dutifully flowered 6 weeks later, and then set fruit. I ate about 2 dozen of these fruit when I visited his home (he would not let me eat too many, because they were making him a fortune, being out of season) and we then inspected his nearby orchards where the chemical had been applied at the usual time. These trees were covered in the most beautiful flowering you could imagine and he was expecting a crop of around 50 tonnes (A$165 000). All the longan orchards in Thailand used this chemical, although no one else mentioned the out of season application to induce flowering.

Opinions varied as to the best way to apply the chemical, with most farmers preferring the ground application method. One farmer I visited in Chiang Mai province physically raked all the litter and mulch out from beneath his trees before applying the potassium chlorate. He did this to aid absorption of the chemical into the ground. The litter was then raked back into place. However the results seemed to be worth the trouble. His 1000 five year old trees had a magnificent crop of fruit, which he estimated at 75 tonne, worth A$250 000. In Chiang Mai I had the privilege of having dinner and a long discussion with two Thai horticultural advisers. They were private consultants working mainly in Cambodia, who informed me that both calcium and sodium chlorate were both just as effective as potassium chlorate in this process, but claimed foliar application was more effective than ground application. Their recommended spraying rate was 50g per metre of canopy (ie a 3m tree requires 150g), six weeks before expected flowering. This matched exactly the rates given by the Chiang Mai farmer discussed above, who claimed to use 150g per tree on his trees of 3 to 4 metres. (They also showed me pictures of high density apple orchards in Cambodia with 36 000 trees per acre. They were harvested like sugar cane and simply left to reshoot from the stump). The use of these chemicals in promoting flowering in lychees is now just starting to be investigated in Thailand. One large grower in Thaton tried it for the first time this past year and did not notice any appreciable difference in these trees compared to his others, as they all flowered well anyway. This year he is going to apply the chemical earlier to see if he can induce an early flowering and has promised to keep me informed of the results. Should such a process be as successful in lychee as it appears to be in longan, the potential for further development would be enormous.

Pruning

This process has been occupying the thoughts of Australian growers for several years now, as the Canopy Management Research team, with funds from the Australian Lychee Growers (ALGA) and the Horticultural Industry Research Development Council (HIRDC) have looked for ways to control canopy size in lychee trees, while maintaining production. For this reason, I was particularly interested to see how growers in Thailand pruned their trees to keep them manageable. The major point I gained from many growers with whom I spoke about this was prune immediately after harvest and heavily. This was best illustrated with a visit to a small orchard at Mae Sai in the Golden Triangle area. His pruning theory was to remove all upwardly growing branches immediately after harvest, leaving his trees in a hollow mushroom shape. The trees then flush heavily for 2 flushes, at which time they are cinctured to prevent further flushes. He claimed figures of 200kg per tree on a regular basis, however I visited his orchard just after harvest and could not see this for myself. I did see his pruning taking place and may attempt his method on some of my larger trees in the near future. Other growers pruned the top out of their trees one year and the sides the next, claiming this was less stressful on the trees than a full prune each year. From what I have seen both overseas and in Australia, I would suggest that pruning, whether it be light or heavy, doesn’t really matter as long as it is done straight after harvest and the trees are encouraged to flush heavily after that. The trick is to manage to stop them in time to provide a period of dormancy before flowering should commence.

Harvesting, Transporting and Processing the Fruit

While some similarities were evident in the Thai harvesting exercise, there were a great many differences. Thai farmers only picked from sunrise to around 10am, but whether this was to promote shelf life as is the case in Australia, or to meet deadlines for transport was not explained. Once in the packing shed the differences were considerable. The Thais use no machinery – all work is done by hand, mostly using imported Burmese people at around A$2 a day. The fruit panicles are roughly graded and split or damaged fruit removed. The fruit is packed still on the panicle into 10 kg boxes, but not refrigerated. The whole process must be completed before 12:30pm, when the fruit is loaded onto a truck to be taken to the nearby depot, where it is loaded aboard a larger truck that leaves for Bangkok at 1:00pm. Here it arrives at the markets in the early hours of the morning, where it is sold that day. There is no need for refrigeration facilities due to the rapid turnover of the fruit. Thai people adore lychee – they are no sooner on the shop shelves than they are walking out the door, so that new stock is required each day in large quantities.

Thai supermarkets also have a very low mark up on local fruits, so that they may compete with the hundreds of street vendors also selling fruit. This of course helps to ensure rapid turnover and fresh product each day. A visit to Talad Thai, the newest and largest Fruit and Vegetable Market in Bangkok, confirmed this. Despite the huge range of fruits available, it seemed every buyer there made sure they had lychee on their list. At 250 baht per 10kg box (farmers were getting between 17 and 19 baht per kilo) the fruit was very inexpensive by Australian standards, but the supermarkets were still retailing them at only 30 to 35 baht per kilo.

Fruit rejected at the farms as not suitable for fresh sale is sent to one of several canneries in the lychee growing areas. On a visit to such a cannery on the outskirts of Chiang Rai, I witnessed this lower grade fruit being processed into canned fruit, boiled down into syrup for the canned product or processed into juice. Nothing was wasted. The wage structures in Australia would preclude such an operation on a seasonal fruit being set up here. Instead our reject fruit is dumped on the ground to rot and be used as mulch – one of the prices we pay for growing a seasonal crop in a rich industrialised country