Setting up an orchard for success – Part 1: Selecting Good Quality Trees

We often get asked the question “how old will my macadamia trees get”? Well, no one is really sure, but what we do know is that they will be around to feed our grandchildren when taken care of. The real question that we need to ask ourselves is will our trees be able to produce above average yields for the next 40 years? Well, as most consultants (the good ones at least) would tell you is that it depends. On what you may wonder? It depends on a range of factors including water, nutrition, tree health etc., but none of these factors are as important as starting with good quality trees and a well prepared and planned orchard. In most orchards that we encounter, especially the ones that collapsed directly after planting, the biggest problems are often related to poor quality trees, poor planting techniques or an unfortunate combination of both. It is therefore essential to ensure that you have good quality trees and that you plant these trees correctly.

So what is a good quality tree?

This is the same as asking what is the best vehicle to have, and there is not a single right or wrong answer when it comes to tree quality. There are , however, a few things that you need to look out for when buying and receiving trees.

 Good trees should: 

  • Be fairly uniform in size and color 
  • Be free from any nutrient deficiencies 
  • Be free from pest and diseases 
  • Have well developed root systems and an abundance of new white root growth 
  • Have a strong graft union 
  • Have a fairly straight stem 
  • Be at least 60 cm tall 
  • Not be grafted too high (>60 cm) or too low (<10 cm) 
  • Have a well-drained medium which is preferably free from soil 

 Bad trees usually: 

  • Lack uniformity in size and color 
  • Have a range of nutrient deficiency 
  • Have a range of pests or diseases 
  • Have poorly developed root systems 
  • Have poor graft unions 
  • Have crooked or damaged stems 
  • Are too tall (>1.5 m) or too short (<50 cm) 

According to the South African Macadamia Industry standard, the following points should be noted when purchasing trees: 

Avoid trees that are stunted, pot-bound or infested with pests or infected by a disease. To ensure the orchard gets off to a good start, select vigorously growing trees free from nutrient disorders, insect pests and disease with a good healthy root system. Buyers should look closely for: 

  • A healthy well-formed root system that is not spiralled or twisted. 
  • A root system that has masses of very fine roots throughout the potting mix. 
  • A potting mix that is well-drained, friable, and free from waterlogging and hard compacted clods. 
  • Healthy, vigorous, well-formed growth with dark green foliage/plant leaves. 
  • A minimum of 150 mm of hardened new growth above the graft. This should consist of at least two growth flushes with a strong graft union. 
  • • Trees that are free from insect pests and diseases. 

When examining the roots the following scenarios are unacceptable: 

It is highly recommended that you visit the nursery from which you have ordered your trees multiple times before the trees arrive on your farm. During these visits you should investigate root development, tree color and size, and try to gauge the number of trees allocated to your order to ensure that your trees that have been ordered are in the nursery. You should also ask your nurserymen the following question on a regular basis: 

1. Are my trees still on track for the agreed upon delivery date? 

2. Can you confirm the cultivars and rootstock used in my batch of trees? 

3. Could you please let me know well in advance if there are any problems with regards to the grafting success rate? 

4. Have my trees been pruned/manipulated as per our agreement? 

5. Would you mind if I bring my consultant to your nursery to come and inspect my trees? 

In conclusion, growers are advised to order trees well in advance of their proposed planting date to avoid any disappointment in tree quality. Most growers are desperate for trees, which is understandable, but waiting an extra six months for your trees could be the difference between a orchard yielding 5 tons/hectare every year for the next 50 years and an orchard that struggles to yield 2.5 tons/hectare in a good year. Selecting a good quality tree is one of the most important things that a grower can do to ensure that they are setting up their orchard for future success. 

– Dr. Theunis Smit

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