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Canopy Management Strategy 2 - Baggenstos method

15 October 2015

Targets

Evenly spread limbs and canopy within the tree with more of a lateral spreading habit and minimal vertical crowding.

Flat on top with a slight slope towards the north.

Height kept low and allow light into middle of tree to get production inside tree, avoiding need for tree to get wider.

Figure 1: Frank Baggenstos' pruning method targets, Bay of Plenty

Benefits

  • Maximise light interception thereby maximising energy captured by the tree
  • Easy picking
  • Access
  • Early flowering
  • Quick return flowering

Method overview


 

Top and side views of desirable tree structures, obtained using the following steps;

  1. Decide on final tree height wanted.
  2. Look for and retain most low, horizontal-spreading limbs.
  3. Form a scaffold of spreading limbs with large gaps between them.
  4. If you wish to retain a higher tree (e.g. 5-7 m) then retain more limbs, but ensure they are not vertically above each other due to the negative effects of shadowing.
  5. The tree should end up with a fairly flat top and an open centre.

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Timing of pruning

Structural pruning
Pruning should ideally be carried out through autumn and winter to avoid sunburn of wood and encourage early regrowth in spring.

If everything is pruned, then outcome will be to miss a crop so this needs to be considered. An "off” year is ideal to start structural pruning as very little fruit is removed, limiting financial impact. If trees are balanced or other factors necessitate pruning in an "on” year then a compromise option is to only prune the Northern half of tree. This maintains production on half the tree and the Southern half receives more sunlight. The Southern half can then be pruned the following year.

Flower and limb pruning to manage stress

Intensity of flowering should be assessed in August - September and pruning should be carried out if flowering is deemed to be excessive. Cuts should be made where wood is about 2cm thick.

If larger limbs should be removed for tree structure, then remove whole limb rather than flower panicles alone.

Assess balance of flowering and new leaf growth in November and if no or very little new leaves flushing then prune flowers and fruitlets harder to encourage vegetative flush.

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Stages of remedial pruning to achieve shape

Before starting
Study the tree to make decisions about what limbs need to be removed to achieve the desired height and structure/scaffold. Ideally want 4-8 main limbs that are evenly spaced with a gap between limbs of 2-4m depending on the total number of limbs retained. Suggested height is 5m. Tree spacing can be 12m X12m but smaller spacing such as 5m X 5m shouldn’t present any issues. If possible, when pruning to leave existing small branches along and at the end of limbs - with more light these will produce fruit quickly.


 

If there are no laterally spreading limbs to choose from, then one on a 45° angle is fine. This can be pruned and one of the regrowth shoots selected to become the main limb that is trained outward.

 Ideally wait for an off year to begin pruning. Refer Timing of Pruning section for more information about when to carry out pruning.

Year 1

Remove crossover limbs, limbs preventing access and any others that you have previously selected so you are only left with the 4-8 main limbs that are well spaced.

Take out the main central vertical trunk to allow light into the inside of the tree. Prune the top of the tree so the Northern side is slightly lower than the southern end. This will allow a similar amount of light to get to the southern parts of the tree as the northern half.

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Year 2

Year 2 follow up pruning is vitally important to establish adequate spacing of the canopy that will hold fruit. Spacing of the main structural limbs was established in year one. Heavy pruning generally encourages a lot of new vegetative growth that can shade each other and limit productivity. It’s important to thin this regrowth to allow enough light into the canopy. If new shoots do not receive enough light they will continue to extend rapidly to seek out light and will have little in the way of leaves and flower and will not contribute much to the tree.

Similar to the spacing of the main limbs, smaller branches, whether they are old or new, also need to be spaced. On each main limb branches and suckers (new growth) should be spaced 1m to 1.5m apart. This spacing should be considered for both vertical and lateral growth. On the outside of the tree where there is a good gap between the main limbs, both vertical and horizontal branches can often be kept without infringing on each other. Closer into the trunk, horizontal branches will more easily crowd each other so these should be removed in favour of vertical ones that can maintain a 1m – 1.5m spacing. Prune unwanted shoots right back to main limb (i.e. flush cut), to prevent regrowth.

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Top view of a section of tree showing spacing of horizontal and lateral shoots off the main limbs to achieve 1m – 1.5m spacing.

Figure 2: Unwanted shoots pruned flush back to the main limb to prevent regrowth, Bay of Plenty.

Year 3

There should not be a lot of pruning to do in year three and production should be good. Any new suckers that are growing in between the ones you have selected should be removed.

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Year 3+

Beyond 3 years you will need to prune the highest 2-3 branches to maintain the height of the tree. Once the canopy has grown to the point that it is limiting the amount of light into the middle of the tree, the central leader regrowth will need to be removed to open the middle back up again. This is important to maintain new growth and flowering inside the tree. If you have good growth, flowering and fruit set inside the tree then pruning can be carried out on the outside to maintain spacing’s and access.

 

 

 

 

 

 

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