Organic Pest Control: How to Treat Scale Infestion
What is scale and how do you know if your plants have it? What organic pest control methods are available? On first sight the plant looks like it has some sort of fungus, a scaly looking substance, with maybe some black sooty look on plant leaves. When you look more closely or rubbing your fingernail over the plant, you find that what may appear somewhat bark-like is really an insect, an insect aptly named scale.
Scale is a favored insect of ants, because it produces honeydew. This honeydew is sticky sweet food produced by sap sucking insects. This honeydew is food for ants. Interestingly, this is a species with no males in the population. Adult females produce fertile eggs that hatch into nymphs, usually orange or yellow colored. Once they settle in a place after being blown by wind, or inadvertently moved, they will settle into this spot and begin feeding in a few days time. In locations with mild winters, all life stages occur at any time of year.
The first signs you may notice that scale are present will be the yellowing or curling of plant leaves, causing them to drop prematurely. The exuded honeydew of soft scales can contaminate fruit, and will, with time turn into a black sooty mold. It is at this phase where ants are often attracted, protecting the scale insects from predators.
After a plant is weakened, branches may die, and die quickly. Broad-spectrum herbicides and insecticides kill scale predatory insects. Properly timed horticultural oil can be applied in outdoor settings. With any control measure, a thorough spray or wiping down with soap on the undersides of leaves is necessary.
Proper nutrition and watering will help to deter scale. Prune off damaged branches. If you’ve larger plants, prune so that there is plenty of airflow. This will not only reduce the likelihood of disease, in areas with hot summers it will increase the natural deaths of scale insects from the higher temperatures.
There are many natural enemies of scale the most important is the parasitic wasp. Other insects include lacewings, mites, and the small black lady beetles with many red, orange or yellow spots on the shiny wings. Growing flowering plants near plants prone to scales will provide habitat for beneficial insects.
The first line of defense is a good offense – remember that the first plants that insect’s attack are those that are not healthy. The health of your plants is a result of f properly fitted pots, well timed watering and appropriate plant feeding. For houseplants or citrus being brought indoors for winter, a good bathing will usually do the trick. Make a bucket of soapy water and wash cloth, washing the entire plant with the soap solution to get rid of scale and any ants that are present. The best type of soap to use is insecticidal soap, although common dish soaps’ will also work.
If any leaves have fallen, dispose of these immediately. If your citrus is in a pot, fertilizing with fish emulsion mixed to package instructions will help give the plant a boost, just be sure to remove and dispose of any bark mulch you may have around the base of the tree. Place the tree in sunlight, then fertilize again in January.
If you’ve any other tips or stories about organic pest control to share about scale, we encourage you to share what’s worked for you in the comments section below!
Scale infestation image from Shutterstock