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Pests and diseases of orchids: How to recognize and successfully fight them!

Orchids in pots are a popular choice for growing at home, as they have a high symbolic value and offer many uses and benefits. However, despite their relatively simple care, orchid plants can also be susceptible to pests and diseases (see below for pictures). To ensure this plant thrives, it’s important to know what these problems can look like and how to treat them. Read on to learn about some of the most common pests and diseases of orchids and how to successfully control them.

Orchid care – recognizing diseases

Orchid care - recognize diseases

These are the most common diseases that can affect your plants.

Powdery mildew – white spots on the leaves.

Powdery mildew - white spots on the leaves

Powdery mildew is a fungal infection that appears as a white powder on the leaves or stems and can cause the leaves to turn yellow or brown. Powdery mildew is unlikely to kill your orchids, but it can affect their health and growth. Powdery mildew can develop due to excessive humidity, poor air circulation, overwatering or overly shady conditions. It can also develop due to weakness or injury, or if your plants are too close together.

You can treat powdery mildew with a baking soda solution. Mix 1 packet of baking soda, 20 ml of canola oil and 2 liters of water and spray your plants with this homemade solution.

Pests and diseases of orchids – black rot.

Pests and diseases of orchids - black rot

Black rot is a common fungal problem. The fungal spores are able to move through water droplets. When water , which contains the spores, comes in contact with orchid tissue, the spores can enter the tissue and begin their life cycle. In adult houseplants, infection begins where the spore-containing water has come in contact with the plant. However, in new potted plants, the susceptibility is much greater and the infection spreads from the site of infection through the plant to the roots.

The fungal infection shows up as dark spots that quickly spread across the leaves and plant tissue as the fungus takes its toll. The spots are soft and release water when pressure is applied.

To prevent the spread of rot in the plant, use a sterile blade to cut out the infested part of the houseplant. Cut into the healthy adjacent tissue to reduce the risk of the fungus remaining in the tissue. Apply ground cinnamon to the open wound to reduce the risk of further infection. Cinnamon acts as a fungicide, and as a bark itself, it is excellent for sealing wounds.

Bacterial brown spot disease can cause wilted leaves.

Bacterial brown spot disease can cause wilted leaves

Visible spots begin as soft, water-soaked patches that become brown or black sunken spots as the disease progresses. An infectious liquid may ooze from the spots, especially at the edge or tip of the leaf. The spots may spread over the entire leaf and then over the entire plant.

Remove the infected parts of the plant with a sterile blade. Cut into healthy tissue to ensure that no bacteria remain in the plant. Then treat your plants with an antibacterial spray or hydrogen peroxide. Apply ground cinnamon to wounds to reduce the risk of secondary infection, and make sure any blades or equipment used in treating the plant are sterilized.

Pests and diseases of orchids – control the most common pests.

How to get rid of the bugs on your plants, discover here!

Thrips – wilted leaves and injured flowers.

Thrips - wilted leaves and injured flowers

Thrips, also known as thunderflies , belong to the Thripidae family with over 6,000 species worldwide. These species are usually between 1 and 5 mm long, making them difficult to see with the naked eye. However, thrips are easily identified by their damage, which includes deformed foliage and injured flowers. Thrips feed on plants by piercing plant tissue with their jaws and then sucking up plant sap. They often feed on buds and flowers, but can also infest leaf and stem tissue. Heavy infestations cause the plants to die.

Because of the way thrips lay their eggs in plant tissue, the eggs and pupal stages are not affected by most pesticides. To actually kill the thrips, you can use neem oil. To make the neem oil solution, mix 5 ml of neem oil with 1 tsp of dishwashing liquid in 1 liter of water. Shake the solution as needed so that the oil is evenly distributed in the water. Pour the mixture into a spray bottle and spray generously on all affected areas of your orchid.

Aphids – the small, green or black insects.

Aphids - the small, green or black insects

Aphids are small, often green or black insects with antennae and soft bodies. They can damage orchids by sucking the sap from the leaves and flowers. This weakens the plant and results in yellow or brown leaves, stunted growth and even death.

You can remove aphids by hosing them off with a strong stream of water. You can also kill them with home remedies, such as neem oil. Remember that aphids like to hide, so it is important to treat the entire orchid, including the undersides of the leaves. It’s best to repeat the process a few times, as it can be difficult to completely remove aphids with one treatment.

Pests and diseases of orchids – mealybugs, scale insects and whitefly cause sticky leaves.

Mealybugs, scale insects and whiteflies are common orchid pests. They can seriously damage the plant and cause weakness, reduced growth or even death.

  • Mealybugs (also called mealybugs) are tiny insects with soft bodies that usually have a white or gray coating. They feed on the sap of plants, causing the leaves to wilt or die.

Control mealybugs on orchids - picture

  • Scale insects, on the other hand, are small insects with hard bodies that attach themselves to the stems or leaves of potted plants. They often appear as small, round bumps on the plant and can cause wilting or death.

Pests and diseases of orchids - scale insects cause sticky leaves

  • Whitefly is a tiny insect that looks powdery white. It reproduces quickly and lives on the underside of a plant’s leaves.

Recognize and control pests and diseases on orchids - whitefly

You can remove any of these pests from your plants with a strong spray of water or a damp cloth. If the infestation is severe, you can use an insecticide to solve the problem. However, consult your garden center first!