Earlier this week a friend posted on Twitter about temperatures at their place expected to go from 68°F one day to 28°F the next. Here in the Eastern Sierra we do that just about every day! Wide temperature swings can cause environmental injury to trees.
This time of year sees a lot of pleasant daytime temperatures, but it still gets very cold at night. We sometimes see injury on fruit trees, especially on the southwest side, during the transition from winter to spring. The warm temperatures in the day can move parts of the plant out of dormancy which may then freeze on a cold night. In Owens Valley, I have seen this most commonly on young stone fruit trees.
Over the past few years here, almost everyone whose trees I have helped train have some sort of environmental injury. While there's not much we can do about our climate, an easy way to reduce issues with sunburn and southwest injury in winter is to apply whitewash to sensitive areas.
A good recipe for tree whitewash is 1 part INTERIOR white latex paint to 1 part water. Parts that get exposed to the sun are good places to whitewash. You don't need to get the entire tree. Once the bark gets thicker, you may not need this any more.
If you already have fruit trees in your yard, go look at them now. You should be able to tell whether your home orchard would benefit from whitewashing.
For questions about environmental injuries or pests, contact our Master Gardener helpline at immg@ucanr.edu or visit our Facebook page.
More information on whitewashing can be found here.