North American Fruit Explorers mailing list at ibiblio

[Don Yellman <don.yellman@webformation.com>]

Mark:

One of the most useful characteristics of dormant spray oil is that it will 
emulsify in water.  This feature also makes it, essentially, water soluble.  
While much of it may remain on the tree in a light rain, the heavier and more 
persistent the rain, the less dormant oil will stay on a tree.  When applying 
dormant oil, wait for a window when there is no rain predicted for at least 
2-3 days.  Your patience will be rewarded by a much more effective oil 
application.  Temperatures should be above 40F and the winds light when 
applying dormant oil.  It is not always easy to find the perfect day to spray.

Don Yellman, Great Falls, VA