Natural Pesticide for Fruit Trees?

Question:

I am looking for a natural pesticide to kill aphids and black mold on my fruit trees. Does anyone have a natural recipe for this?

Hardiness Zone: 10a

Helene from Sarasota, Florida

Answer:

Helene,

If by "natural" you mean organic, you might try applying horticultural oils. These oils were originally developed to prevent transmission of viruses (often spread by aphids) and to kill hard-to-control pests that overwinter on trees. They work on aphids and other soft-bodied insects by smothering them, but they also work on caterpillars and many plant diseases. Most are made with natural ingredients-usually derived from different types of plant oils. Horticultural oils should not be applied during freezing weather, at temperatures above 100 degrees, during excessive humidity or when rain is in the immediate forecast. Some oils cause leaves to scald and burn so they should be tested on a small area first before wider application.

There are also many organic insecticidal soaps effective at controlling aphids. Again, they can cause leaves to burn so they should be tested in small areas before applying. You can make you own with 1-1/2 teaspoons of liquid dish soap to 1 quart of water. These need to be reapplied after it rains and may need to be washed off within a few hours/days to avoid scalding leaves.

Teas made from wormwood or nasturtium are also said to repel aphids from fruit trees. These are made by mashing or blending 1 to 2 cups of fresh leaves with 2 to 4 cups of water and leaving them to soak overnight. You can also make them by pouring 2-4 cups of boiling water over 2-4 cups of fresh or 1 to 2 cups of dry leaves and letting them steep until cool. Strain out the pulp and add 2-4 more cups of water. Adding a small amount of liquid dish soap (1/4 teaspoon) will help the "tea" stick to the leaves when you spray it. Apply this weekly and make sure you get it on the undersides of the leaves.

I think the simplest and most effective chemical-free treatment for aphids is simply to spray them off with a stiff jet of water from the garden hose. You don't have to worry about burning or scalding your leaves and your tree will appreciate the water.

Ellen