Preventing spring freeze injury on grapevines using multiple applications of Amigo Oil and naphthaleneacetic acid

• Single applications of Amigo Oil successfully delayed bud break in ‘Edelweiss’ grapevines up to 4 days.
• Two and Three applications of oil exhibited greater delays ranging from 4 to 8 days.
• Applications of 10% (v/v) Amigo Oil were not phytotoxic to buds and had no deleterious effects on harvest or fruit characteristics.
• Naphthaleneacetic acid did not delay bud break and showed no effect on harvest or fruit characteristics.

‘Edelweiss’ is an important grape cultivar grown in the Midwestern part of the USA. It is one of the earliest cultivars in the vineyard to break bud, making it very susceptible to late spring freezes. ‘Edelweiss’ primary buds produce a significant amount of fruit, while unlike many other hybrids, the secondary and tertiary buds will have little to no yields, thus making it important to protect the primary buds from a late freeze. The objective of this research was to determine if multiple applications of Amigo Oil or naphthaleneacetic acid (NAA) achieve a greater bud delay when compared to single applications. ‘Edelweiss’ vines were treated in January, January and February or January, February and March. Amigo Oil was applied at 10% (v/v) and NAA at 1000 ppm with a custom built all-terrain vehicle (atv) sprayer. All treatments of oil led to a significant bud break delay ranging from 1 to 8 days as compared to the control. None of the treatments were phytotoxic to buds or negatively affected yield or fruit characteristics. Grape growers in climates with the potential of late spring freezes may consider the use of Amigo Oil or NAA as a potential means to protect their vines from freeze injury.