Training system improves plum quality
Adopt a Drapeau-Lehner training system to improve plum quality and maximise production efficiency, recommends top fruit consultant, Leon Jahae.
Unlike imported produce, British plums can be on retailers’ shelves within days after picking, and it’s because of this they are experiencing a comeback and increased consumer demand.
To ensure quality expectations are met, Mr Jahae recommends that trees are trained using the Drapeau-Lehner system – a ‘fruit wall’ without the need for expensive high-density planting.
“The Drapeau-Lehner is an older training system used mainly for stone fruit. It takes slightly longer to establish than conventional fruit walls, reaching full potential in three-four years rather than two, but offers all the advantages without the additional costs and risks involved,” said Mr Jahae.
“Trees are trained so the central leader grows at a 45-degree angle below a 90-degree wire. Among the many benefits, this allows excellent light distribution in the lower part of tree, uniform fruit quality, as well the ability to conduct all husbandry and harvest from ground level.”
Prunus species, including plums and cherries, are apically dominant. Excessive top growth can lead to poor light distribution in the lower part of the trees, resulting in quality reduction.
Pruning can encourage even stronger apical growth and less vitality in the lower part of the trees. But with the Drapeau-Lehner system, trees are planted at an angle, reducing this apical dominance and the need to trim the height of young trees.
The system
By using Pythagoras’ theorem (a2 + b2 =c2), hypotenuse ‘c’ is the central leader, ‘a’ is the spacing between the trees and ‘b’ the final height from soil level.
For example, 200cm tree spacing with 220cm final height would equate to a central leader of 297cm. Compared to trees planted conventionally, this gains 40cm before the top of the leader is above the next tree.
Mr Jahae, who works alongside Agrovista in his consultancy role, added: “Side shoots above the original frame are ‘tied in’ under a 90-degree angle from the central axe. Because they compete with the leader and become leader-like themselves, this further reduces apical dominance.
“To form the structure, wires should be installed one at frame height and then every 25-30cm, as well as metal poles every 6-7m. Trees then need to be supported and caned individually at a 45-degree angle.
“As well as fruit quality, training trees in this way means there’s no need for picking platforms and harvest can be automated. At a time when British growers want to capitalise on consumer demand, I will be recommending this system as a way to maximise production efficiency.”
The Drapeau-Lehner system is a modified version of the Drapeau system, developed by Swiss grower Lehner.