Defeating Orchid Pests and Diseases

An orchid that has pests or a disease should be treated quickly. Any infestation can move to other orchids in short order. Pests may come with new orchids. Place the new plants away from the old ones for 2 or 3 weeks.

 Orchid Care

Pests and disease are not as attracted to healthy plants as they are to plants that have become vulnerable. Some diseases develop because of bad growing conditions. Below are the general requirements of orchids. To properly take care of orchids, know the variety of the orchid and any special requirements.

  • The majority of tropical orchids like well drained soil and a special potting mix.

  • Different species have different lighting needs.

  • Some species of orchids like hot and some cool temperatures.

  • Too much humidity invites disease.

  • The majority of orchids like 40 to 60 percent humidity.

  • Orchids need good air circulation.

  • The majority of orchid species like limited fertilizing.

  • The fertilizer should be balanced but use a weak solution.


The worsts pest for an orchid is scales. These pests suck out the plants juice. They are tiny brown or yellow insects. There are two types of scales: armored scale and soft scale. Mealy bugs are a variant of scales that appear waxy and their texture is like meal. Some other pests that attack orchids are slugs, caterpillars, thrips, whiteflies, spider mites and fungus gnats.


Before using a pesticide to protect orchids, isolate the particular disease or pests causing the harm. Then get a pesticide that gets treats that specific problem. There are 4 kinds of pesticides: contact poisons, stomach poisons, systemics and fumigants.

  1. Contact poisons must be sprayed onto the pest.
  2. Stomach poisons must be eaten by the insect.
  3. Systemics work by the plant ingesting them and then the pests eat part of the plant.
  4. Fumigants are breathed in by the insect and it kills them.

When spraying the pesticide cover the plant well, including the bottom side of the leaves.

Do not spray orchids during the heat of the day. This causes damage to the plants. A sticker spreader or liquid soap (surfactant) can be added to the pesticide to help it stay on the plants. Alternating pesticides can help prevent the insects from becoming immune to the pesticide.


Looking the orchids over a couple of times a week for problems can prevent the spread of insects or disease. The sign of fungus is a brown or pink spot on the flower. Punctures in the flowers indicate mealy bugs, aphids or thrips. These are the signs of virus infection: leaves are streaked in irregular pattern, the flowers color is streaked or the flowers appear deformed. The physiological diseases are caused by the plant's environment being out of balance like too much water or not enough light. A prime example is root rot caused by over watering and poor drainage.

It is best to learn the signs of various pests. At the first inkling of a problem, the orchid looking unhealthy, try to learn exactly what is causing it. There is a list of approved pesticides, but it changes as chemicals are removed or added. You can get advice about pesticides for orchids by consulting a local plant nursery, agricultural agent or the Orchid Society.