I took a walk through my yard on Sunday afternoon in the 70 degree sunny weather. It felt more like being in San Diego rather than Sonoma County. The daphne is in full bloom filling the air with its fragrance. As I admired some of the flowers I noticed a shiny film on the leaves. On closer inspection I was surprised to find aphids had infested the whole shrub.
The warm winter weather is giving the problem insects a head start on their spring feeding of our plants. I found only one of my daphne shrubs was affected but I would recommend checking your roses and other shrubs for aphids. Look for the shiny residue on the leaves and also check on the undersides of the foliage where they will be found. It is important to treat for aphids early. They are very efficient at reproducing and it's best not to let them go untreated. Aphids have sucking and piercing mouthparts which they use to extract the carbohydrates or sugars from leaves and soft stems. Aphids ingest more of these carbohydrates than they can process and the excess is excreted from their bodies in the form of "honeydew". This honeydew is the sticky substance that can become so saturated on tree leaves that it drips onto sidewalks, streets and vehicles. Ants may also be present when aphids have infested a tree or shrub. Ants actually encourage the aphids to grow and spread because they utilize the honeydew they secrete as a food source. They even work to protect the aphids from other beneficial insects that would consume them.
Aphids are one of the easiest insects to control because they are soft bodied. Without an exoskeleton they have little protection from non toxic pesticides like insecticidal soaps. Some people prefer to spray them off with a hose but I prefer a method that is more likely to stop the aphids in their tracks. I take a household spray bottle used for mixing cleaning products or even re-use a glass cleaner sprayer to mix my own insecticidal soap. If you are reusing a container make sure you rinse it well before preparing your mixture. Use two tablespoons or so for a 16 oz. container and three tablespoons for a 24 oz. container of either Ivory dish soap or a Castille soap such as Dr. Bronner's and fill the container with water.
Spray your roses or shrubs on the undersides of the leaves for best results. I grab the branches and bend them over gently to I can easily spray the foliage. Leave the soap mixture on the foliage for an hour or two and hose off the plant with fresh water. A small sprayer will work fine for roses and smaller shrubs. If you are trying to spray aphids on a large tree you will need to use a hose attached spray bottle similar to the type that Miracle Grow uses for their foliar feeding fertilizers. Another option is to use a pump type or backpack sprayer. I recommend having separate sprayers for your insecticides and herbicides. Marking each sprayer with a non erasable marking pen or using a permanent label will help prevent costly mistakes. The last thing you want to do is treat your aphids with a dose of Round Up that ends up killing your shrub or tree.
One advantage of our early warm weather means bees will be more active early in the year for pollination. Early blooming fruit trees like apricots will have better fruit production if bees are out and about when they bloom.
For more information about caring for your trees and shrubs visit the "articles" tab at our website at treeprosonoma.com.
Ron Wallace, Certified Arborist #WE 0979A