There are several insect problems associated with camellias, but none can be more serious than Tea Scale.
Tea Scale is believed to have originated in Southeast Asia and made its way to America attached to camellias that were imported. The very name implies that it is associated with Tea or what we usually call Camellia sinensis. This insect attacks all species and varieties of camellias along with other plants such as hollies, tea olive, and citrus. If left unchecked, the problem can intensify to cause premature leaf dropping, decline in the health of the plant, and even death. Although the problem is extremely common with camellias, it can generally be controlled easily with an understanding of the cause, the cure, and the prevention.
Tea scale is a small insect that affects many different plant species throughout regions of the world with moderate climates. The scientific name for Tea Scale is Fiorinia theae. It was first described as Tea Scale by E.E. Green in 1900 as a result of insects that he found on Tea Plants in India. One of the first noticeable symptoms is yellowish spots on the upper surface of the leaves. When these leaves are turned over, there is usually a major infestation of Tea Scale on the underside of the leaves. The primary distinguishing feature that makes Tea Scale easy identify is the white powdery appearance on the underside of the leaves.
Close up View of Severe Tea Scale Underneath the Camellia Leaf
Tea Scale will damage camellia foliage when the insects attach themselves to the underside of the leaves. These insects suck on the bottom of these leaves resulting in a draining of nutrients from these leaves. If the leaves are severely damaged, they will not be able to effectively produce carbohydrates through photosynthesis. When leaves are damages severely by Tea Scale, they tend to fall off as their drain on the plant outweighs their benefit. The fact that these insects live on the underside of the foliage protects them, and it is an important consideration in controlling this problem. Tea Scale continuously reproduces during the warm months of the season. Their life cycle is between 45 and 60 days, but each female lays between 10 and 15 eggs, so left unchecked, Tea Scale could get out of control in a very short time period.
If plants are severely damaged with Tea Scale, major pruning can minimize the problem, but the best method of control is going to be by spraying with an appropriate insecticide. Years ago, many gardeners used harsh chemicals to control Tea Scale. One of these dangerous sprays was an insecticide called Cygon. It was sprayed under the foliage of the plants and/or painted on the bottom portion of the stem. It worked from a systemic action and generally did a good job of controlling scale. The biggest problem of using chemicals like Cygon was that the gardener was exposed to these chemicals. Today, most of the harsh chemical insecticides like Cygon have been removed from the market.
Always Spray Thoroughly Underneath the Foliage to Effectively Control Tea Scale
Dormant Oil Insecticide has also been used for many years to control Tea Scale. The most recognizable brand name of Dormant Oil from years gone by was Volck Oil Spray. It was used on camellias and citrus. It used to come in a paste emulsion and later as a liquid. It needed to be applied when the temperatures were mild such as during the spring or the fall. Spraying this insecticide during extreme cold or extreme hot temperature ranges could seriously damage the plants. This Dormant Oil spray was much less dangerous to the gardeners applying it, because it did not contain dangerous chemicals. As the oil penetrated the insect colonies, it simply suffocated the scale insects.
Today’s Horticultural Oils have been refined to be much more effective that the older Dormant Oil sprays, and the engineering has allowed for most of the newer sprays to be used all season as well. Usually during extreme temperatures, the rate must be changed to account for the temperature changes. There are many different brands available today that can do an excellent job in helping you control Tea Scale, but with all chemical application, it is important to ALWAYS READ THE LABEL!
There are Many Different Brands of Horticultural Oil. Always Read the Label before Applying!
Over the years, we have learned some tips that we would like to share to help you control Tea Scale:
- Always spray under the foliage. Tea scale uses its habitat as a protected area. If you are spraying for Tea Scale, spraying the top of the leaves only is a waste of time.
- Remember that Tea Scale is an insect. It is not a fungus, so if your friendly neighborhood garden center sells you a fungicide to control the problem, you are wasting your time and your money.
- There are several types of spray equipment that you can use to apply insecticides such as pump up sprayed, hose-on sprayers, and power sprayers. If the problem is severe, you will be able to do a more effective job of controlling the problem with hose-on sprayers of power sprayers because you have more pressure to force the oil into every little crevice.
- The best insecticidal control that we have found for controlling scale is Horticultural Oil sprays. There are many different brands, but these sprays are generally very effective if applied correctly, and they are much less dangerous for you and the environment than more hazardous insecticides.
- When you look under the leaves of your camellias and see the white powdery Tea Scale as you are spraying, keep spraying until all of this white powdery Tea Scale has turned brown. If there is still white residue under the leaves after you have sprayed, you may not have done a good enough job to control the problem.
- If your Tea Scale problem is extremely severe, you may need to use several applications. Always read the label to determine how soon you can come back and do an additional application.
- Once you have your Tea Scale problem under control, spray several times a year as a preventative maintenance. You do not have to be as extremely thorough as you would for major infestations, but you can easily manage the problem and keep your camellias happy and healthy all year long.