Selecting Varieties for Commercial Orchards
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Selecting varieties to plant in commercial orchards is a complicated and to a degree subjective problem.
There are many to choose from, performance varies according to the region where they are planted, there is no perfect variety for all situations, and different people will often place different levels of importance on aspects of variety performance. The following is how we suggest that you select varieties for commercial plantations.
Many comparisons between varieties report Yield of NIS per Tree, but this is in general a poor measure of tree performance.
Firstly, the way that processor’s price tables are worked in Australia, means that growers are effectively paid for First Grade Kernel free of rejects. Yield of First Grade Kernel is the measure that is most closely related to Income.
Yield First Grade Kernel (kg) = Yield NIS (kg) x Sound Kernel Recovery (%) x First Grade (%)
Secondly, tree yields can be misleading if taken in isolation, because in the end you should be interested in Income per hectare. A variety may have a high per tree yield, but if it is excessively large may still perform poorly when assessed on a per hectare basis. Equally a small tree planted on a wide spacing will not achieve acceptable yields per hectare (more on this in the next section).
Yield First Grade Kernel per Hectare (kg) = First Grade Kernel per Tree (kg) x Trees per Hectare = First Grade Kernel per Tree (kg) x 10,000 / Between Row Width / Within Row Width where trees will fit at nominated trees/ha
When making decisions about new orchards, we believe you should convert all Yields, Incomes, Costs, Profits etc to a per hectare basis.
We believe the first decision should be what tree density you intend to plant the orchard. There is an almost unlimited range to choose from. Some examples are
Low Density - 10m x 5m (200 tree/ha) Medium Density - 8m x 4m (312 tree/ha) Medium-High Density - 7m x 3m (476 tree/ha) High Density - 5m x 2m (1000 tree/ha)
Most new orchards are planted at medium to medium-high densities.
In general a low density orchard will take much longer to reach full production, because the trees will take many years to completely cover the otherwise open and non-productive orchard floor. Also the large trees will require larger equipment to manage them in the long term.
High density orchards have higher set up costs per hectare (trees cost approx $10 ea), and will require more intensive management - such as pruning - earlier in the life of the orchard. However the benefit is that the orchard reaches full production much sooner. An orchard planted at 1000 tree/ha can achieve 5 tonne/ha in six to seven years, whereas a low density 200 tree/ha orchard may take 20 years to achieve the same result. Low & high density orchards should achieve similar maximum yields per hectare, but there are still some questions as to whether high density orchards can maintain these yields in the long term. To get the full benefit of early returns from high density orchards it is best to plant precocious varieties.
The planting density of a new orchard will influence the selection of varieties. It is unlikely that a small, compact upright tree like A16 would ever achieve high yields per hectare if it is planted at low densities. It would probably never fill the orchard, leaving a large area of the orchard unproductive. By the same token planting a large tree such as HAES 781 at high densities would mean excessive management would be required to keep the orchard under control.
Hidden Valley Varieties are assessed on their ability to produce high First Grade Kernel Yields per Hectare. In general we have a preference for medium to small trees suitable for medium to high planting densities.
We believe the most important trait in selecting varieties for planting is Yield of First Grade Kernel per Hectare, for reasons explained above.
But when selecting varieties it is important to take all traits into account, rather than concentrating only one or two. To a degree the importance you place on various traits is a subjective decision, and will also depend on the mix of varieties you are considering. For example, many people consider it desirable to have all varieties ready for harvest at the same time so they have a short harvest season. Other people prefer to spread the harvest out to reduce risk and reduce the need for large capital equipment to handle to harvest. Also it is desirable to select varieties that are all more or less the same tree size.
We believe kernel characters are of low importance at the moment. In general, any variety that has been released will have acceptable kernel in terms of flavour and appearance. There is some debate at the moment as to whether small or large kernels are most desirable. We prefer large kernels, because they are less costly to handle, simply because there are less of them for any given weight. Others prefer small kernels for chocolate coating etc - but if you do choose this option make sure the variety has a large percentage of wholes, otherwise you just end up with small halves which are expensive for processors to sort.
Huskspot has become more important in Australia in recent years, but to date there is only limited data regarding varieties. Certainly some are more susceptable than others. Huskspot may become more of a management problem than a spray problem as we begin to understand more about it, but a tolerant variety will always be easier to manage with low chemical use methods.
Pollen compatabilities have also gained prominance in recent years. However we believe there is still more work to be done before it’s importance can be quantified. The trials to date have been based on raceme by raceme tests, and designed to highlight different compatabilities. There is only very limited data on actual orchard situations. For these reasons, we believe you should give this data a low priority in selecting varities, but a high priority when determining your orchard design (see 5. below).
There is a lot data available on varieties, mainly produced by QDPI and NSW Ag from regional trials set up in 1987. This can be accessed through the Australian Macadamia Society (see Links). Unfortunately there is almost too much to comprehend and often the format has changed from year to year. It is probably better to narrow down the varieties you are considering first, and then go to these sources to get down to details. QDPI’s Agrilink publication for macadamia should be available soon and it will include a section on the main varieties.
5. Choose at least Three Varieties then Design & Plant orchard according to Polleniser Compatabilites
We recomend that you select at least three varieties. This reduces the risk of varieties not performing up to expectations. It also gives you the potential to maximise pollenation.
As mentioned previously we do not believe that you should select varieties based on their pollen compatabilities. However once you have selected your varieties, you should use the compatability tables to design your orchard in a way that will maximise cross pollenation - planting the most compatablie combinations close to one another. Keep flowering periods in mind as well.
We recomend planting complete rows of varieties, rather than mixing the varieties in the row. While this may slightly reduce pollenation, it will make the orchard much easier to manage.