Development of apple growth forms in commercial cultivation

In the late 50s and early 60s in Canada, columnar growth habit apple trees and clones and mutants were named after their discoverer "McIntosh Wijcick". The exact discovery date is still unknown, but because "Spur" varieties were extremely popular at that time, that clone was used in cultivation. It is a spontaneous mutation and therefore a naturally evolved tree type. Every clone that is known nowadays derives from the clone "Wijcick". Pillartrees or column trees are for example known for early flower bud development at the side shoots and very short internodes. Generally this variety is time saving, because winter pruning is mostly not necessary and harvest becomes more effective. 

The "Ballerina" variety, originating from East Malling in England was one of the first varieties that derived from this cultivation, but, because it is very prone to disease and has a very low fruit quality, it is not very popular with consumers. These trees are the basis for further cultivation all over the world. Since the beginning of the 90s, Hochschule Geisenheim University has a very intensive cultivation program with the aim of finding suitable varieties for commercial growing, both for fruit for direct consumption and for beverage production. 

Our main cultivation goals are

-       fruit quality
-       loose foliage and short shoot leaves
-       long pedicels
-       resistance (especially against fruit tree cancer)
-       suitability for mechanical harvest

Modern consumers expect a very high fruit quality, exquisite flavor, juiciness, attractive appearance (red varieties are especially popular) and a long shelf life. 

A loose leaf foliage prevents refuge areas for pests on the tree thus ensuring effective plant protection. The short shoots with the flower buds must be such that the leaves on the first internodes grow well and that a large leaf area is formed over them. These leaves are crucial for the nourishment of the fruits.

Long-stalked fruit is a special selection criterion, since several fruits on a single stalk with short stalks result in early pressing of the fruit. The column-like growth habit means that many crosses have too short a stalk, so this must be considered in the selection process.

An early end of budbreak in columnar varieties leads to a very high flower quality, meaning that, with good fertilisation, very many fruits can be produced in an inflorescence. These lead to high competition in relation to shoot growth and to the depletion of carbohydrate reserves near the fruits. This can prevent the formation of new flower buds in this part of the stem explaining an 'alternating bud' tendency in many varieties. 

Resistance breeding is also very important, and here we select primarily from a high tolerance to blight and mildew. Particularly important in columnar varieties is a high tolerance or even resistance against tree cancer (Neonectria ditissima).

In the development of cider fruit varieties in particular, the possibility of mechanical harvesting must also be taken into account. The exact requirements for the tree are still unclear and are currently being tested and defined in cooperation with harvesting technology manufacturers.

Hochschule Geisenheim University has developed the "Proficats" series. CATS is a registered trademark of Hochschule Geisenheim University and stands for „Columnar Apple Tree System“. The Proficats series includes five direct consumption varieties and we are also working with the fruit juice industry to develop high quality cider fruit varieties suitable for regional production close to the fruit juice industry. In Europe there are around 20 test hectares planted with Geisenheim varieties.


Author: Prof. Dr. Peter Braun, Hochschule Geisenheim University, Department of Pomology

Blossoming CATS-Plant