Improving fruit quality and tree health of Prunus persica cv. ‘Sandvliet’ through combined mineral and salicylic acid foliar applications

• Commercial foliar formulations containing salicylic acid were evaluated for their efficacy to improve fruit quality and enhance tree health of Prunus persica cv. ‘Sandvliet’.
• Both Xanbac™ and Alexin™ were effective in controlling Xanthomonas infection on both leaves and fruit.
• K-Max™ and Alexin™ treatments confirmed the positive role of K in enhancing disease resistance.

Foliar products that can address crop protection through systemic resistance and simultaneously also enhanced fruit quality will promote a reduction for the requirement of chemical applications in commercial orchards. Such products may include flavonoids and salicylic acid combined with mineral nutrients such as calcium, potassium, magnesium and boron which are widely linked to enhancing plant resistance to pathogens. In this study the efficacy of foliar formulations to improve fruit quality and enhance tree health of Prunus persica cv. ‘Sandvliet’ over two seasons were evaluated. Alexin™-containing foliar applications were effective in controlling Xanthomonas infection on both leaves and fruit of ‘Sandvliet’. The efficiency was however related to the infection incidence which varied between organs and seasons. During the second season, all treatments reduced shoot length compared to the unsprayed control. K-Max™ and Alexin™ treatments confirmed the role of potassium (K) in disease resistance. Xanbac™ reduced the severity of Xanthomonas infections, but the efficacy varied between seasons. Applications of Alexin™, Cropbiolife™ and K-Max™ significantly increased fruit size to the control.