Delaying bud break in grapevines with various substances as a prophylaxis against spring frost

Different substances can be used to delay the development of buds or shoots in grapevines. Such a delay often requires early application, sometimes even during the bud dormancy period. This slows shoot development and reducing susceptibility to late frost events. Once green parts of the shoot become visible, frost resistance significantly decreases. Consequently, a developmental delay increases frost stability for a certain period. Retarded bud break has been primarily standardized using oil spraying. However, variations remain, especially concerning the timing of application. Other substances, particularly phytohormones, have not shown consistent and thus useful effects, although under certain conditions, developmental delay was noticeable with Ethephon application. Standardization in these procedures appears challenging and requires further development. Despite the delayed bud break of few days, frost damage could not be avoided during the spring frost in 2024. It seems essential to prolong the period of retardation.