On Sunday 21st March the NEC Committee and members of the Ingham and Cairns branches visited the tropical fruit orchard of Mr Alf Uechtritz, north of Innisfail.
First up, Alf showed us his computerised irrigation headworks complete with a large tank used for diluting soluble fertilizers for injecting into the irrigation system (fertigation). A map of the orchard on the shed wall indicated the different irrigation sections and a large white board bore instructions concerning the irrigation, fertilizer and spraying programmes. The whole area is irrigated from the adjacent Treganthenan River. "Growflow" soluble fertilizer 16-17-12 plus trace elements was currently being used through the fertigation system to the undertree sprinklers.
Fruit is exported to southern markets and currently Abius were being packed into cell pack polystyro boxes as the preferred cardboard mango boxes were not available. Fruit is size-graded, but no fruit with marks of any kind are packed for export.
Amazingly, no fruit fly sprays are applied nor are trees netted against birds and bats. If any spraying is done, a "Micromaster" controlled droplet sprayer is used with two hydraulically-driven fan applicators: a very efficient method of spraying tree crops, as droplet size is controlled for better coverage of fruit and foliage. The sprayer uses 600 litres of spray mixture to cover spray 350 four-year-old trees at a time. Alf gave us a demonstration of the sprayer.
Part of the orchard was planted with alternate rows of Mangosteens at 8 metres apart and Durians at 12 metres apart in the row.
Other orchard trees were interplanted within the row, for example: one block had "main crop" Mangosteens around 6 metres apart with a 'cash crop' of Abius interplanted between them. The earlier-bearing Abius are now providing some income, but eventually they may be removed once the later-maturing Mangosteens begin to earn their keep. Another block had a 'cash crop' of Star Apples interplanted between 'main crop' Durians with the same idea in mind.
This close planting within the row using early and late-bearing varieties gives a much earlier return from the block. It thus provides an income to help cover the costs of labour, fertilizer, irrigation and maintenance needed to bring the "main crop" variety to a stage when it begins to pay its way. The idea seems to be working quite well at present, as the Abius and Star Apples are already providing an income. Just how it will work out in the long run will be interesting to follow up in the future.
Trees are kept pruned, the Abius having had their tops taken out. One has to be careful doing this as Abius tend to sunburn. Similarly, Star Apples are not allowed to get too high. With the latter, new growth made after pruning will flower and bear fruit.
The shade tree Albizia falcataria has been planted in parts of the orchard. Older trees of this species observed at Woopen Creek in a block of Mangosteens appeared to have made extremely vigorous growth with large surface roots. One would have thought that these would compete with orchard trees for moisture and nutrients. In East Africa, Albizia stipulata (syn. A. chinensis) is commonly used as a shade tree in tea, and although less rampant-growing, it still tended to compete a bit too much with the crop. Leucaena leucacephala (syn. L. glauca) was also discussed, but this has the disadvantage of producing masses of seedlings. Seedlings do not appear to be a problem with A. falcataria.
As windbreaks, Alf has planted what he called the Galip nut, Canarium indicum. Actually, according to H F Macmillan's book the correct name is Java Almond, C. luzanicum (syn. C. indicum and C. commune) . Can't find the name Galip Nut in the book. These are starting to produce nuts although they are still comparatively young trees. They did, however, appear to be making a fairly extensive surface root system. They are wind-resistant and produce a good timber.
Alf also has windbreaks of a minimum of 10 different varieties of clumping bamboo, one of which he called Arundinaria acea. These, although still young, were already about 50ft high and fairly dense. The root system did not appear to be too extensive. Could be a good subject to consider as a windbreak.
A forage harvester type of grass mower equipped with a side thrower is used between the rows which places the cut grass very neatly along under the trees as a mulch. Because of close planting within the rows, only the inter-row area is mown, thus considerably reducing mowing costs.
Alf showed us some Ilama trees, a type of custard apple, grafted on soursop rootstocks. The trees did not appear to be thriving because of some incompatibility at the graft union. The rootstock was much thicker than the Ilama stem.
There was some discussion about varieties of fruit. Alf remarked that the Z2 Abiu was the juiciest and Z4 was a firmer fruit, both varieties were nice and sweet; the Mark Wheatley pomelo was the best white-fleshed variety, Boswell Pink was hard to peel and 134 and Rang Rin the best Rambutans, in his opinion.
It is of some significance to compare FNQ with other tropical fruit-growing areas of the world. Alf made the interesting observation that the climate in FNQ is an extremely harsh one compared to New Guinea where he was previously. It is certainly a much harsher climate than Uganda or Zaire. Here we have at times extreme heat, much wind, cyclones and long months of dry weather with high evaporation rates. If we had two weeks without rain in Uganda, we considered it a drought!
Abius and Star Apples seem to do alright in our FNQ climate. But is it too harsh for Mangosteens and Durians compared to the climate in their native countries? Perhaps they should only be grown in more protected microclimate areas better suited to their needs, and have we got the right varieties/selections of these two crops considering the high cast and long lead-up time of bringing them into production? Is intercropping as previously described the answer? Time will tell!
One of the great advantages of these orchard walks is the interchange of ideas and the many useful bits of information one gleans from the results of other growers' practical experience, and to compare different ways of doing things around the block.
Alf is to be congratulated an his high standard of orchard management. He gave us a most interesting conducted tour of his property and we wish him all the very best for the future.
DATE: May 1993
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