Effect of centrifugal tree training on pests and pathogens in apple orchards

The effect of tree architecture on the development of the main apple pests and pathogens was investigated from 2002 to 2005 at the INRA Gotheron experimental station. The original Solaxe (OS) was compared to the centrifugal training (CT) system, in which the thinning out of fruiting spurs along the trunk and on the proximal and underside parts of branches modifies within-tree environment conditions. Infestation levels of the rosy apple aphid Dysaphis plantaginea (Passerini) (Hemiptera: Aphididae) and of the European red mite Panonychus ulmi (Koch) (Acari: Tetranychidae) were significantly lower in the CT than in the OS system, in 2002 and 2004 for D. plantaginea, and in 2003 for P. ulmi. For the green apple aphid Aphis pomi De Geer (Hemiptera: Aphididae), differences between systems varied with years. Fruit damage by the codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) tended to be higher in the CT than in the OS system. The incidence of apple scab Venturia inaequalis (Cooke) G. Wint. was lower in Spring (2002, 2004) in the CT than in the OS system, but increased faster in CT than in OS in Summer, with no difference in fruit damage at harvest. Due to several factors, including pest or inoculum removal when thinning out spurs, within-tree microclimate, shoot density and/or growth dynamics, tree architecture influences the development of pests and pathogens. These results open a wide field of research on the use of tree architecture as a means to modulate pest and disease development