Orchid Pests and Diseases

Dealing with pests is always part of orchid gardening. Even healthy orchids suffer to some kind of pathogens. Gardening is impossible without the participation of insect and non-insect pests, diseases caused by bacteria, viruses, and fungi.

Observing your plants will help you spot and treat problems before it become worst. A wide variety of pesticides, bactericides, and fungicides is available on the market. Make sure the cleanliness of the area, plenty of air and bench space (plants are not crowding), immediate isolation of infected plants, proper control of humidity, and a routine of spray with noninjurious insecticide, sponging fungus-infected spots, and dusting injured parts with sulphur to check the spread of rot.

It is hard to diagnose bacterial and fungal diseases. Water left standing on a leaf or in the crown of the orchid plant may encourage the growth of bacteria. This will cause the plant to become watery, brown to black lesion that spreads through the plant rapidly. Fungi disease includes black rot; leaf spot fungi cause dark, sunken spots on orchid leaves. If you spotted these kinds of diseases, remove all affected areas and treat them appropriately. Increase ventilation and ensure that stems and leaves are dry by dusk.

Bacterial brown spot is most prevalent in phalaenopsis, and is as deadly as black rot with cattleyas. This disease is active under wet conditions. As a symptom of the diseases, brown, watery blister on a leaf quickly spreads until the plant is gone. To prevent, remove infected leaves and spray immediately with pesticides.

Brown rot is caused by the bacterium Erwina cypripedii, plagues paphiopedilums in particular. This disease starts as a small brown spot on the leaf and spreads quickly, forming a brownish patch and usually gives off unusual odor. Remove infected leaves and spray with pesticides to prevent the bacteria from killing the plant.

Root rot is rotting of the root caused by Rhizoctonia fungus that attacks the roots. Infected roots eventually die, and may affect the rhizomes. Infected areas appear brown plus shriveling of pseudobulbs and leaves. What to do are: unpot the infected plant and remove the affected tissue, repot in clean material and spray with fungicide.

Leaf-spotting is caused by Cercospora species for the most part and shows brown to black spotting on the leaves. In order to prevent this disease, make sure that the plant has enough air and reduce misting the leaves with water.

Petal Blight spots orchid flowers. This disease is caused by Botrytis cinerea that requires water on the flower surface to infect. The problem arises when humidity is high that leads to water condensation on the flowers. You will start to see black dots to appear on the flower. Remove affected flowers from the growing area to reduce source of infection. Keep the flowers dry by decreasing the humidity. Fungicide can be used too.

Several viruses are also found in cultivation of orchids. Symptoms can be confused with symptoms of bacterial and fungal diseases. Virus infected plants must be discarded for there is no known cure at present. Prevention is the only way to control viruses from attacking your plants. Always sterilize pots and cutting edges before use to prevent transmitting of virus from one plant to another.

Pests also share their part in orchid cultivation. Most prevalent are: scale which secrete a hard, waxy covering that repels most pesticides unless a wetting agent is added. Scale usually appears as a circular raised mound attached to any part of the plant and can kill the tissue. To prevent, you can apply a cotton swab with alcohol to minimize the infestation or pesticides for stronger control.

Mealy bugs are a problem especially with leafy orchids. You will start to notice white, sticky infestations that start as a patch under the leaves. Be on the lookout so you can catch any infestations before bugs can multiply. Alcohol for isolated mealy bug and pesticides for entrenched infestations will solve the problem.

Spider mites suck dry leaves they attack making the leaves look silvery and dry. They rapidly multiply in dry conditions and are hard to see but the damage they leave is very visible. To prevent, you have to increase humidity and air circulation as well as applying contact insecticide.

Aphids can be controlled by insecticidal soap or chrysanthemum extract. Aphids are small green to yellow insects that transfers fungi and bacteria through their piercing mouthparts.

Slug and snails feed on flowers, leaves, and roots in the evening. They more a problem when plants are outdoors. These pets can be controlled by placing shallow bowls of beer or pellets in the growing area, driving slugs away from the flowers.

Extreme care of insecticides is emphasized. Keep it away from children. Follow manufacturers’ precautions such as wearing mask and rubber gloves when using insecticide.

In order to keep your orchids healthy, providing the most favorable environment for vigorous growth and repotting at the proper time with fresh potting material will help minimize the troubles with pests and diseases. Orchids with healthy leaves, roots, and flowers are signs of pest and disease-resistant plant. The key for fighting pests is to observe.