Sweet cherry training to improve fruit size and quality - An overview of some recent concepts and practical aspects

The Goblet, with its open-center framework, remains the standard sweet cherry training system in France. Generally, it is more time- and labor-consuming than more recent systems based on the use of size-controlling rootstocks (e.g., MaxMa Delbard 14 Brokforest, Tabel Edabriz, Gisela 5) with higher tree densities/ha. For the past decade, a research program has developed at INRA to integrate knowledge of the growth and fruiting characteristics of the cherry tree more effectively, so as to reduce the time before the first commercial harvest as well as the labor spent in training. Our training proposals are based on two principles: maintaining the natural hierarchy between the trunk and side branches, and controlling the growth of the trunk and the branches by bending rather than by heading cuts. These main principles define the Solaxe training system developed initially for apple. Recent developments of Solaxe cherry orchards have given rise to the need to control crop load more effectively, which can become excessive in response to the use of both dwarfing rootstocks and branch bending, in order to maintain optimal fruit quality (size and color). In traditional systems, such as Goblet, the balance of fruiting to vegetative growth is obtained by annual repeated heading or thinning cuts, usually during winter because of the greater time available during this period. This results in marked vegetative reiteration mechanisms, which may generate an imbalance between growth and fruiting. Experiments have been carried out to analyze the long-term effects of thinning cuts specifically applied to fruiting spurs. This method is called "extinction" training. This paper presents an experiment on various degrees of extinction applied to 6-year-old Solaxe-trained trees of 'Summit' on Tabele Edabriz. The best fruit sizes were obtained by the removal of 30 to 50% of the fruiting spurs. Experiments are underway, in connection with the Mafcot network (Ma (i) over cap trise de la Fructification - Concepts et Techniques; Fruiting Control - Concepts and Applications), to integrate these methods into an overall strategy for canopy management.