Large-dwarfing rootstocks can protect apples from sunburn

Research Brief Publication Date: May 06, 2024
Last Updated: July 11, 2024

Hao Xu, Suzanne Blatt, and Danielle Ediger


This study investigated if rootstock size selection can contribute to extreme heat resilience in ‘Buckeye Gala’ apple trees, measured through fruit sunburn damage.

This research is a step towards developing a comprehensive apple rootstock evaluation that will help tree fruit growers adapt to climate change. Small-dwarfing rootstocks, such as Budagovsky 9 and Malling 9, are commonly used in tree fruit production because their small tree size allows for a higher planting density and a higher fruit yield per hectare. However, as climate change worsens and extreme weather events become more frequent, the shallow root system, small trunk, and small canopy of small-dwarfing rootstocks may put them at a disadvantage in the long-term.

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Sunburn-damaged apples after multiple heat waves in 2021. Photo by Hao Xu.

About this Brief

This brief was prepared by the BC Food Web team with the help of Hao Xu and is based on the following scientific journal article:

Xu, Hao., Blatt, S., & Ediger, D. (2023). Tools for climate resilience in tree fruit I: large-dwarfing rootstocks can alleviate sunburn damage in “Buckeye Gala” apple. Canadian Journal of Plant Science, 103(1), 128-132.


Key Findings

  • The vigor (size) of a rootstock impacts an apple tree’s ability to tolerate extreme heat.
  • When water supply was sufficient, large-dwarfing rootstock varieties Geneva 935 and Geneva 4814 created larger tree canopies and reduced heat stress on the trees, which led to fewer sun-damaged ‘Buckeye Gala’ apples.