Growing dragon fruit
The trials that were undertaken in the Gascoyne from 2006 onwards have provided some advice in growing dragon fruit.
Plant support
Trials have shown that plant support is essential. Treated pine poles at 1.8 metre intervals were used to support the 2006 plantings with four rooted cuttings per pole. Support frames were fitted to the pole tops.
In 2011 four alternative wire-with-pole structures were trialled, with plants spaced at a 1 metre row interval.
Trellis safety consideration
The weight of the developing plant must be taken into account when planning a trellis. Support pole stability may diminish if the soils become saturated after heavy rainfall or local flooding.
If action is not taken regularly to remove overlapping stems at the top of the plants, the covered stems will contribute little in terms of crop but may become a source for rot and disease and may dangerously overburden support frames.
Support wires tend to cut into those plant stems that rest above and upon them. To avoid this risk, sections of the support structure were fitted with white plastic coated ‘horse sighter wire’ rather than plain fencing wire.
Natural fibre twine is recommended for tying (sisal or cotton) as this biodegrades efficiently and resists ultra-violet light.
Prune to stimulate flowering
Prune back regularly, removing overlapping growth to maximise light penetration. If pruning established plantings, where buds and immature fruit are present, favour these and remove surplus unproductive stems; particularly those low on the plant.
Overcoming sunburn
The Gascoyne trial was conducted under crop net to overcome the sunburn issue in the arid sub-tropics.
In the Gascoyne, high levels of fruit splitting can be expected and 73% of the July-ripened fruit was affected to some degree in 2013.
The red flesh variety is impacted more by sun because the white flesh form ripens earlier and over a shorter (particularly during April).
To minimise this risk, take every opportunity to advance late summer flowering and fruit set by pruning individual plants hard in mid to late April.
Scale infestation
Scale infestation is usually associated with ant activity and is frequent on developing flower buds and on new stem growth.
There are no registered chemicals for scale control on the crop in WA, however organic industry-approved horticultural oils can be used when diluted at the recommended rate with clean water.
Take care to apply oil to developing fruits to the necessary minimum because the skin of oil-treated fruit is particularly susceptible to scarring.
Scale control oil applications should only be made when temperatures are low, to minimise stem discolouration and scarring.
Plant maturation and harvest
The red flesh variety can commence fruit set about 14 months after cutting plant-out (if plant-out is in April or early May while relatively warm conditions favour fast establishment).
The white flesh variety commences fruit set later. (This may explain the wide disparity in yield between the red and white varieties in 2013. The 2014 yields will provide clarity.)
The red flesh variety is productive in Carnarvon from early February through to the end of July. However, as explained earlier, July crops can be substantially damaged by mature fruit splitting and growers are urged to adopt pruning regimes structured to discourage July fruit maturation.
Pick the mature fruit as soon as colouration is complete, preferably in the cool of the morning. Transfer immediately to the coolroom to optimise storage life (beyond 14 days in-store is achievable).
Cut the fruit from the stem and cut the dried flower from individual fruits as you pick. The fruit structure is prone to tear. (If the dried flower is pulled away, an entry point is commonly created at the fruit apex that can potentially harbour dirt and insect pests.)