North American Fruit Explorers mailing list at ibiblio

[Jwlehman@aol.com]

In a message dated 1/2/2011 4:23:25 PM Eastern Standard Time, alandhaigh@gmail.com writes:

> The only research that I've seen that successfully involved white paint to delay bloom involved painting all the wood, including the small bud wood which I suspect is most important of all.  White paint on the trunk seems to be mostly about protecting from southwest injury but I'm not at all sure it would be helpful in protecting apricots from being killed by fluctuating temps in early spring.  Show me the research!


Alan is correct. It has been reported that painting the entire tree white, including the buds can delay bloom. I know of no research papers reporting delay by only painting the South side and delaying root thaw.  

Many trees have early sap flow, example maple. During this flow period the sap stops at night when the temps drop below freezing. If the temp of the root system as well as xylem and phloem can be held below the threshold of sap flow it should delay bud expanson, delaying bloom time. This theorized delay would not be more than a few days at most. But one or two days could be enough to avoid frost damage in a small percentage of the flowers as the bloom period can be more than week. The rise in spring temperatures is different yearly, changing the effectivness yearly. Temperature variation during the bloom period can vary the length of the period. 

The possible effectivness of this would vary with species. Example: Persimmon doesn't bloom until June in zone 5. Delaying early sap flow would not delay flowering. Would likely not delay apple either. The best poossiblilty would be apricot which is the species about which this question was asked.  

Theory only, not proven by test that I'm aware of. This could be the basis for amateur apricot flowering research. 

Jerry