Horticultural Oil – Application in Winter
Q: I want to spray horticultural oil on Magnolia scale. However, I understand that due to recently mild temperatures serious harm to the plant can occur. Once the weather becomes wintry again, how many days or weeks until I should wait to proceed with the oil application?
A: Do you have a label that says you’ll damage the tree when spraying in mild weather? My understanding is that spraying in freezing weather or really hot and humid weather is bad. Why would mild weather be a problem?
I use Colorado State University’s Insect Control: Horticultural Oils, as my reference. You might want to take a look at it.