By Tom Prest

Now that frost has driven the deciduous trees and shrubs into full dormancy, they can be cleaned up for the nest season with dormant spraying. Many of the diseases and pests that infest your plants are especially vulnerable to sprays now and some, such as peach leaf curl, can only be controlled with winter spraying.  With their foliage gone, deciduous plants are much less prone to spray damage at this time of year than they are in the heat of summer.  Let’s take our gardens into the new season cleaned up, dressed up and ready for the party!

LIME SULFUR (calcium polysulfide) and SPRAY OIL are combined and sprayed together.  Lilly Miller POLYSUL kills fungus over- wintering on the surface of your plants.  The spray oil acts as a spreader-sticker for the disease control and as an insecticide, as it smothers adult insects, pupae and even eggs that pass the winter on the bark.  Ortho VOLCK OIL is the petroleum oil commonly used for this.  If you would like a lighter oil that can be used widely even in warmer weather, Master Nursery PESTFIGHTER YEAR-ROUND SPRAY OIL IS NOW AVAILABLE.

Copper sprays lack the ability to control insects but are more effective than lime sulfur on certain diseases (especially bacterial infections) and can be used on apricots, which will not tolerate lime sulfur sprays.  Lilly Miller MICROCOP  is a fixed copper replacement for the old Bordeaux mixture.  It is a dry powder that cannot be applied by a hose-end sprayer (use tank or trigger sprayers) but comes with a resinous spreader-sticker that holds up in rainy weather. 

Monterey LIQUI-COP is a liquid that lacks the spreader sticker but can be used in a hose-end sprayer for convenient application to large areas or tall trees.  Recently E. B. Stone has introduced a highly refined COPPER SOAP that offers the convenience and effectiveness of Liqui-cop but using only 20% as much copper, making it the favorite of environmentally concerned gardeners even though it is not truly organic.