Different crop load management on columnar apple trees: first year results

Research on the optimisation of crop load management in apple trees is mostly concerned with cultivars of common growing types.
However, there is not much research work related to crop load management of columnar apple cultivars.
After some decline in interest, the columnar apple cultivars are again considered promising, especially for 2D canopy systems.
The interest in 2D systems is driven among other things by the prospect of increasing robotisation in orchard management.
One of the main limitations for the introduction of columnar apple cultivars in conventional orchards is the high tendency to alternate bearing.
To overcome this problem, we have designed several thinning strategies in order to achieve stable flower sets and yields in the columnar apple cultivar ‘Redspring’ grafted on M26 rootstock.
Three main strategies were tested, which could be carried out by robots.
First, only the removal of flower clusters was performed.
Second, the removal of flower clusters was combined with subsequent thinning leaving only the king fruit.
Third, the removal of flower clusters was followed by the removal of fruitlets on the required crop load.
In all of these strategies, the level of thinning was set at 2, 3, or 4 units 10 cm^‑1 of central axis height.
The results of the first year indicate that a stronger thinning to 2 units of flower clusters 10 cm^‑1 height without fruitlet reduction could avoid alternate bearing and ensure stable sufficient production.
This type of flower clusters thinning could be done by robots for crop load management of columnar apple cultivars.

II International Symposium on Precision Management of Orchards and Vineyards

L. Laňar, K. Scháňková, L. Nývlt

alternation, flower cluster, fruitlet, Malus sp., return bloom, thinning, yield

https://doi.org/10.17660/ActaHortic.2024.1395.37