Impact of Amigo Oil and KDL on Grapevine Post-Budburst 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 inter-specific hybrid cvs. Noiret and Traminette to evaluate the effectiveness of two sprayable products in reducing post-bud burst freeze damage without impacting grape production, fruit composition, wine chemistry, and sensory perception. Treatments consisted of a vegetable oil based-adjuvant, Amigo^®, applied once during the dormant season to delay bud burst, hence reducing the chance of a damaging frost event, and a potassium fertilizer (KDL^®) applied within 24 hr prior to a predicted frost event to increase plant freeze resistance. Amigo oil application significantly delayed bud burst 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 occurred in late spring 2015 at the Noiret and Traminette vineyard (minimum temperature: −3°C). At this time, the percentage of buds reaching bud burst was no longer lower in the Amigo oil-treated vines than other treatments. Neither Amigo oil nor KDL reduced freeze damage and crop losses of the hybrid cultivars. The lower osmotic potential of Noiret KDL-treated leaves as compared to the control did not translate into increased freeze resistance under our experimental conditions. The delay in bud burst of 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 on the V. vinifera cultivars (i.e., lower cluster weight and percentage of bud survival). Further studies are needed before Amigo oil can be recommended as a frost avoidance strategy.