Scale

Also known as Scale Insects

Description

Scale are insects which measure between 1/16 and 1/4 inch. They are slow moving and have round, oyster-shaped bodies that come in various colors, including white, gray, black, brown and yellow. Scale insects thrive on almost any part of African Violets, feeding on the juices from the leaves and stems. If left untreated, Scale are fatal to African Violets.

Common species include Fern Scale (Pinnaspis aspidistrae) and Brown Soft Scale (Coccus hesperidum).

Distinguishing Symptoms

• Visible insects. Scale are slow moving insects, measuring 1/16 to 3/8 inch, and they have oyster-shaped bodies.

If your African Violet has this symptom, it probably has Scale.

Other Symptoms

• Leaves pale. They appear yellow or grayish in color.
• Leaves have honeydew on them. Honeydew is a shiny, sticky substance left behind by certain insects. Honeydew will often host a thin, black fungus called Sooty Mold. Other insects which leave behind honeydew include Aphids, Leaf Mealy Bugs and Whiteflies. These insects, however, are easily distinguished by their physical characteristics.
• Leaves have a black fungus on them. This is probably Sooty Mold, which finds a host in the honeydew left behind by Scale and other insects. When Sooty Mold is present, the upperside of the leaves will be covered with tiny, dark speckles.
• Plant growth is slow.

Treatment

First, isolate all affected plants in order to prevent any further spread. Next, if the infestation is not too severe, try removing the Scale with a soft-bristled toothbrush which has been dipped in either soapy water or 70 percent isopropyl alcohol.

For heavier infestations, spray with Acephate or Malathion (as directed on label). Repeat every six to seven days until Scale has been eradicated. (Note: Since Malathion may discolor flowers, Acephate is preferred. Acephate is available in household insect sprays. However, many of these sprays contain a specific additive which may damage the foliage of African Violets. Therefore, if available, use a soluble powder, and mix your own spray.

Prevention

Always isolate new plants until you can positively determine that they are not infested.

Thoroughly wash hands before handling your plants.

Before repotting, pasteurize soil and disinfect pots with a 10 percent bleach solution, i.e., 1 part bleach to 9 parts water. Always isolate new African Violets until you can determine that they are not infested.

Important Note on the Use of Pesticides

Please note that almost all pesticides are formulated for specific uses and conditions. When applied incorrectly, pesticides can cause ill health or damage to plants. Therefore, when using any kind of pesticide or chemical treatment, always apply as indicated on the product label.

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