Effect of grapevine training systems on susceptibility of berries to infection by Erysiphe necator

Abstract

The effect of two training systems on the development of powdery mildew caused by Erysiphe necator in berries of Chardonnay and Cabernet Sauvignon grapevines was examined. Disease development was monitored on berries from vines trained to either vertical shoot positioning or as free-positioned, topped vines with no foliage support wires. No fungicides were applied and powdery mildew development was recorded following artificial inoculation of young berries. Disease incidence was higher in berries collected from the vertical shoot system than in berries from the free-canopy vines. Incubating the berries under the reciprocal training system had a slight effect on PM development with the more susceptible berries of the VSP system but not on berries from the free canopy. The data suggest that the training system decreases disease development mainly through an effect on the susceptibility of the berries. The latter were less vulnerable to artificial inoculation performed in the laboratory after prior exposure to higher radiance intensity. The free-position system may therefore be useful in reducing the use of fungicides.Keywords Disease resistance . Powdery mildew . Microclimate . Vitis viniferaPowdery mildew (PM) of grapes caused by Erysiphe necator Schwein is one of the most widespread and destructive diseases in vineyards in all viticultural regions. Although this fungus can develop in a wide range of temperatures and humidity levels, regionwide differences in the level of epidemics between years are apparent. Differences in disease severity between vineyard plots have been attributed to grape variety (Doster and Schnathorst 1985), vine vigour (Valdes-Gomez et al. 2011;Calonnec et al. 2009) and to the applied chemicals (type, timing and application method) (Deliere et al. 2010). Seasons in which disease levels are much higher or lower than average in many vineyards in a given area have been associated with weather conditions (Calonnec et al. 2008). Gadoury et al. (2003) have shown that grape berries develop an ontogenic resistance to powdery mildew infection two to three weeks after bloom. Austin and Wilcox (2011) compared the effect of two training systems, VSP (VSP 0 Vertical Shoot Positioned) and Umbrella-Kniffen, showed a significant effect on powdery mildew development and explained it with the differences in canopy density. In our previous study (Zahavi et al. 2001), we demonstrated that different training systems of the vines affected the microclimate in the cluster zone and had a clear effect on Eur J Plant Pathol (2012) 133:511-515

Adaptation of Local Grapevine Germplasm: Exploitation of Natural Defence Mechanisms to Biotic Stresses

“…Shaded P. viticola infected leaves, besides showing the lower content of flavonoids compared to full light exposed ones, also displayed the highest disease severity [69]. A similar result was obtained with the artificial inoculation of detached berries with E. necator: in this case shaded berries showed the highest susceptibility to the pathogen [79].…”

Pathogenicity Traits Correlate With the Susceptible Vitis vinifera Leaf Physiology Transition in the Biotroph Fungus Erysiphe necator: An Adaptation to Plant Ontogenic Resistance

“…Other practices, such as thinning of old leaves, will decrease the photosynthesis of younger leaves, thereby potentially delaying their ontogenic resistance, whereas shoot topping of younger leaves does not impact leaf photosynthesis per unit of leaf area (Petrie et al, 2003). Consequently, thinning might be less favorable to increasing leaf resistance than shoot topping, without considering the potentially positive effect of light on tissue receptivity (Zahavi and Reuveni, 2012). Other cultural practices, such as minimal pruning, which results in increased shoot numbers, reduce leaf and shoot size, and more synchronous leaves emergence (Poni et al, 2000), could allow the plant to escape disease by simultaneously causing all leaves to behave as a source.…”

“…For powdery mildew, the process has been underscored for berries, on which infection stops when berry sugar content reaches 8% (Delp, 1954), and it is characterized by a low penetration rate of infectious structures following potential modification of the structure and chemical composition of the cuticle (Ficke et al, 2002). The level of irradiance received before inoculation can strengthen ontogenic resistance through modifications of berry physiology, such as decreases in pH and K concentration and increases in polyphenol and anthocyanin concentrations (Zahavi and Reuveni, 2012). Ontogenic resistance also exists in mature leaves, which suffer less infection (Doster and Schnathorst, 1985).…”

Selection and validation of suitable reference genes for qRT-PCR analysis in pear leaf tissues under distinct training systems

“…A good training system is an important foundation for manipulations of tree planting arrangement and canopy geometry to improve the penetration and distribution of photosynthetically active radiation ( PAR ) for the purpose of optimizing photosynthetic carbon fixation and fruit quality [ 1 ]. Canopy structure can alter microclimate conditions (temperature, humidity and other environmental factors) and thereby indirectly affect disease incidence [ 2 , 3 ]. Currently, there are various training systems used for growing pears, such as the spindle system, open vase system, trellis system and so on.…”