Date of this Version
‘Edelweiss’ is an important grape cultivar grown in the Midwestern part of the USA. This grapevine is tolerant to extreme winter temperatures which can be experienced in the areas where it is most widely grown. ‘Edelweiss’ is one of the earliest cultivars in the vineyard to break bud, making it very susceptible to late spring freezes. The primary buds of ‘Edelweiss’ 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 Naphthaleneacetic acid (NAA) or Amigo Oil has a greater effect on bud delay when compared to single applications. ‘Edelweiss’ vines were treated with one, two, or three applications of NAA or Amigo Oil at monthly intervals starting in early January. The purpose of the Amigo Oil and NAA application was to delay bud break without affecting desired characteristics such as yield or fruit composition. Amigo Oil was applied at 10% concentration (v/v) and the NAA at 1000 ppm with a custom built all-terrain vehicle (ATV) sprayer. All treatments of Amigo Oil led to a significant bud break delay ranging from 3 to 11 days as compared to the control. None of the treatments resulted in negative effects on yield or fruit characteristics. A controlled laboratory experiment was also conducted, where single bud cuttings were forced in forcing solution containing 200 ppm 8-hydroxyquinoline citrate and 2% sucrose at 25°C under 12 hour days. Treatments of one, two, or three applications of 1000 ppm NAA and 10% (v/v) Amigo Oil were applied to single buds at weekly intervals. Julian days until bud break were recorded and treatment-related bud break delays were observed. Two and three applications of oil significantly delayed bud break ranging from 14 to 24 days. All NAA treatments led to significant bud delay ranging from 6 to 9 days. Grape growers in climates with the potential of late spring freezes may consider the use of Amigo Oil as a potential means to protect their vines from freeze injury.
Advisor: Paul E. Read