I often consider this combination to be the first line of defense against a season full of pests. I use it throughout my garden on fruit trees, flowering ornamental trees & roses. These are the plants most suited for a Dormant Oil treatment though its unlikely to harm surrounding evergreens, though overuse on Spruce has been known to effect their colour. Adjacent tender leafed plants should be covered to protect from overspray.
The oil will help control overwintering insects such as: blister and rust mites, red mite eggs, aphid eggs, scale insects, twig borer, plum black knot, peach leaf curl, as well as overwintering fungal diseases. Which, much to my chagrin am all too familiar with, having battled each at one point or another in my gardening career.
The key is timing, you want to spray before the plants leave their dormant phase. This is when the temperature is over freezing for at least 24 hours, but the leaves have not yet opened. Mix according to directions with water, lime sulphur or complementary insecticide in a garden sprayer, ensure to start at the top of plant. If it’s a tall tree you may need a ladder, I know I do. Make sure the weather is fair with no wind, you don’t want this spray blowing back in your face. Cover the plant until there is light run off though it shouldn’t be a heavy drip.
Finally spring has arrived and we can get out in our gardens!!