From the Desk of Ed Hume: Dormant spraying to control Winter insects and diseases

January 4, 2010 at 2:03 PM Leave a comment

Good morning everyone, and a happy Monday to you all!  Before we get on with our post today, I’d like to take a moment to discuss our plan with the blog for 2010.  As with when we started, we still plan to update three times a week; podcasts on Mondays, articles on Wednesdays, and video clips on Fridays.  We may sometimes change our Monday and Wednesday content (as with this week) to better suit the flow of the material over the week, but generally we will stick to our stated schedule.

Our biggest change is that we will no longer be dividing our weeks up into themes.  We will be staggering our content so as to provide you all with more variety throughout the week.  For example, this week we might have an article on pest control, and then a podcast on it will appear two or three weeks later.  We chose to do this for two reasons.  First, as mentioned before we want you to have more variety through the week.  Second, this method allows us to provide you with more contextually-appropriate garden information at the best time (ie three different posts on three different Winter lawn care tips in one week so you can act on them all at once).  We hope you will enjoy our new schedule, and look forward to hearing your input on it.  Remember, if there’s something you think that works or doesn’t work, let us know!  We’re here for you.  In addition, if you have any suggestions for what you’d like to know more about, leave us a comment and we would be happy to accommodate your requests.

We’re really excited about this year and hope that we can make it an even better year of garden information for you.  Now, on with the article!:


Many insect and disease problems can be eliminated by adopting a simple Winter spray program.  Spraying during the Winter dormant season allows the home owner the opportunity to eliminate some of the insect and disease problems before they occur.  Deciduous trees and shrubs, roses, fruit trees, and deciduous ornamentals should be sprayed with a dormant spray anytime from three weeks after the last leaves have fallen until two or three weeks before the buds begin to break with new growth in the early Spring.

Weather conditions will determine the best time to spray.  In this Northwest region, generally two or three Winter sprayings are recommended to control the greatest number of insect pests and diseases.  The first spraying should be in December, the second spraying in early January, and the third spraying two or three weeks before the buds burst.  Spray at a time when there is no chance of rain for a period of at least 24 hours, and avoid spraying during freezing weather or when a strong drying wind is blowing.  Before spraying, check for dead, decayed, or damaged areas on the branches or the trunk of the deciduous trees and shrubs. Clean these areas with a sharp, sterile knife, as such areas offer protection for over-Wintering insects.  After cleaning the area, treat it with a pruning-healing compound to help avoid future insect and disease infestations.  Sometimes one or two leaves will remain on the deciduous tree or shrub. If this happens, simply remove the leaves as they might contain either insect eggs or a disease.  Fruit that remains should also be removed for the same reason.

Liquid lime-sulfur and oil sprays are generally used for the Winter dormant spraying of most all deciduous trees, shrubs, and roses except for stone fruits, like apricots.  Use a copper spray for them.  Lime sulfur will burn and discolor evergreens, so never spray them as a standard-type dormant spray.

Today, some winter sprays are simply called ‘”Dormant Spray.”  Several are natural or organic, so be certain to read the label and follow the application directions to the letter.  These sprays and the combination lime-sulfur and oil sprays will help control over-Wintering scale, spider mites, aphid eggs, scabs, powdery mildew, and moss on deciduous plants.

Be careful when using the lime-sulfur or copper sprays near painted surfaces as they both will stain.  Be especially careful that spray mist does not drift onto such surfaces.  Tacking up a piece of polyethylene, and old sheet, newspapers, or similar material should give adequate protection and it takes only a few minutes to put up and take down.



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From the Desk of Ed Hume: Gardening in 2010 Ed’s Podcasts: Pruning Trees

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