[2005] Growing Fruit Trees – Edited by Lespinasse and Leterme

English trans. published by W. W. Norton 2011.
Original Title: De La Taille à la Conduite des Arbres Frutiers

Contents (selected)

Apple (Pierre-Éric Lauri, Jean-Marie Lespinasse, w. Michel Ramonguilhem)

  • Floral and Vegetative Characteristics
  • The Cultivated Apple Tree: A Composite
  • Principles of Training – The Basics
  • The Tree’s Development During the First Three to Four Years
  • Dormant Pruning vs Summer Pruning
  • The Tree’s Natural Balance
  • The Fruiting Branch
  • Spurs
  • Spring Pruning by Artificial Spur Extinction
  • Thinning the Fruit
  • (Subsequent) Pruning

Pear (Bernard Florens, Pierre-Éric Lauri, Marcel Le Lezec, w. André Belouin)

  • Vegetative and Floral Characteristics
  • Development and Varietal Behaviours
  • Rootstocks
  • Principles of Training – Planting
  • Training the Tree
  • Tree Evolution in the First Four Years
  • Palmette Training
  • Light Penetration and Fruiting Branch Selection
  • Regulating Fruit Load
  • Renewing Old Trees

Key Concepts – Intro

Emphasis throughout on allowing the tree’s natural architecture to be expressed, limiting pruning to essential maintenance – damage & disease control – and encouraging optimal fruiting, rather than pruning to a specific shape or structure.

[p. 11 – 13] “… the most recent documents on natural fruit tree behaviour … have proved that a tree that is rigorously and repetitively shaped will gain height. This process creates a tall, closed frame that slows fruit production.”

“Why deny the evolution of pruning? Quite simply, because of a cultural phenomenon: the manifestation of our collective memory. For over two centuries it has been written and reiterated that shaping is a fixed technique … we have not yet understood that pruning can be a delicate and harmless procedure that benefits the plant, its shape, and this its way of growing and producing.”

“… we now realise that structuring fruit tree shapes has no scientific reason and no physiological purpose.”

Key Concepts – Apple

Botanical Classification of Apple

[p.29] “Most apples grown in North America today are domestic varieties of Malus pumila Mill., the common apple of Europe.”

Later amended / explained to: [p.32] “The botanical single species of apple tree … doesn’t exist. The cultivated apple tree is named Malus x domestica Borkh., with the x indicating its pluri-specific origin.”

The Tree

Floral and Vegetative Characteristics

Inflorescence = basal (leaves, vegetative buds) + terminal (floral corymb) parts.

Carrier axis = either short spurs (approx 5mm – 25mm) or long shoots (up to 1.5m). Those with inflorescences are generally shorter.

Bourse shoots develop from an inflorescence bourse, either as very short dards which are likely to be vegetative in following year, or longer crown brindilles which are more likely to produce a further inflorescence and additional bourse (= ‘bourse on bourse’ development).

Morphology

Wide range of shapes and fruits due to characteristics of wood (degree of flexibility) and placement of inflorescences (spur, non-spur, intermediate). Strong terminal blossoming leads to natural branch bending (arching), more so than trees that fruit on short branches (columnar habits / spur-bearing). “Spurs that are two years old and older begin bearing flowers.” [p.36]

[p.36] Four types of trees:

Type 1 = spur type / columnar. Thin trunk, few branches, short laterals, bearing fruit on entire length.

Type 2 = As above but with more and stronger scaffold branches.

Type 3 = Trunk dominant in relation to scaffold branches. Fewer short laterals, more bowing of branches.

Type 4 = Trunk and branches “readily comparable”, may take on a dome shape. Basal branches less hardy. Fruiting zone at tips of branches, which causes arching.

[p.37] “In general, types 1 and 2 have a naturally occurring alternate bearing habit. By contrast, type 4 varieties are relatively consistent in their production.”

The Cultivated Apple Tree: A Composite

Combination of variety + rootstock allows for a wide range of solutions for various soils & situations and determines tree’s final height & volume.

[p.37] “The indirect consequence: a so-called hardy, vigorous rootstock generally delays flowering, whereas a tree grafted on a weaker rootstock starts fruiting in the second year after planting … Another effect of less vigorous rootstocks: the higher the grafting point is from the ground, the more it will transmit its less vigorous tendencies to the variety.”

Principles of Training

The Basics

Over 30 years of research the authors observed natural characteristics of apple trees which include:

  • During the first years of growth, if left to their own devices, un-pruned trees will develop a “solid and harmonious edifice” of branches on the main trunk. “Generally this natural architecture of the tree is better adapted to early and consistent fruit production than are artificial shapes imposed on the tree from pruning (vase / open centre, palmette etc.) [p.38]
  • In later years, fruiting “occurs according to specific modes for each variety (diversity of spur disposition on the branch, number of fruits per corymb etc.)” [p.38]
  • Some varieties are reliably year-on-year bearing, others will revert to a biennial pattern without intervention by the orchardist.

Important to respect the natural processes of tree growth and modify our thinking to work around these processes because “shaping a tree with clippers transforms and sometimes destroys its natural mechanisms. It forces the tree into an artificial shape and fruiting pattern that are quite contrary to its natural functions. Today we know that the best way to produce a sufficient quantity of high-quality fruit is to let the trees grow freely, balancing growth with fruiting by using our knowledge of the trees’ vegetative behaviour … we switch from ‘pruning’ to ‘training’, from constraining to educating.”

The “naturally advantageous conditions” for quality fruit production include:

  • horizontal branches (via natural or artificial bending or arching)
  • moderating the number of fruit buds (via extinction pruning)
  • maintaining one to two fruits per inflorescence (via thinning)

Growers need to consider three key stages post-planting:

  • the development of the tree for a balance between growth and fruit set.
  • the fruiting branch and its different modes of fruiting.
  • the spur system’s “autonomy and durability”.