Impact of Amigo Oil and KDL on Grapevine Postbudburst Freeze Damage, Yield Components, and Fruit and Wine Composition

Abstract

Field studies were conducted in 2014 and 2015 on Vitis vinifera cvs. Lemberger and Riesling and on interspecific hybrid cvs. Noiret and Traminette to evaluate the effectiveness of two sprayable products for reducing postbudburst freeze damage without impacting grape production, fruit composition, wine chemistry, or sensory perception. The treatments consisted of a) one application of a vegetable oil-based adjuvant (Amigo) during the dormant season to delay budburst and reduce the chance of frost damage; and b) application of a potassium fertilizer (KDL) within 24 hrs before a predicted frost event to increase plant freeze resistance. Amigo oil application significantly delayed budburst in Lemberger and Riesling in both years (six to 11 days), but the delay was less pronounced in Noiret and Traminette (two to four days). A frost event (minimum temperature −3°C) occurred in late spring 2015 in the Noiret and Traminette vineyard. At that time, the percentage of buds that had reached budburst was no longer lower in the Amigo oil-treated vines than other treatments. Neither Amigo oil nor KDL reduced freeze damage and crop loss in the hybrid cultivars. The lower osmotic potential of Noiret KDL-treated leaves compared to the control did not translate into increased freeze resistance under our experimental conditions. The delay in budburst in Amigo oil-treated vines did not impact fruit composition at harvest in any of the cultivars tested or the sensory perception of Riesling wines. Amigo oil applied at 10% concentration caused, however, phytotoxic effects (i.e., reduced cluster weight and bud survival). Further studies are needed before Amigo oil can be recommended as a frost-avoidance strategy.