Spots on the orchid leaves
Orchid stains can come in all shapes and colors. The most common are black, yellow or white spots on the orchid leaves. Sometimes they are grayish or brown, dry or watery. Each type of stain on orchid leaves indicates a different cause of their formation – care errors, disease or pest. See where the stains on the leaves of an orchid come from and how to treat orchids with stains on the leaves!
Black spots on the leaves of the orchid
Black, dry and rough to touch, extensive spots on the orchid leaves are a result of sunburn. They are in places of direct sunlight. Such damage is irreversible because the leaf parenchyma has been destroyed. To avoid burns to orchid leaves, avoid exposing plants to direct sunlight. They feel much better in places with diffused light than on a strongly lit window sill.
Black-brown, convex and air-filled, pale ring-shaped, streaky or irregular, often very numerous, and yellow (chlorotic) spots visible on orchid leaves gradually darkening and destroying tissue are symptoms of viral diseases. Viral diseases are very common in orchids. Unfortunately, there is nothing you can do to treat viral diseases.
If you observe the above-mentioned symptoms on orchids, you should remove such plants as soon as possible. Viral diseases are transmitted by pests (especially aphids). Therefore, fighting pests of houseplants plays an important role in the fight against viral diseases of orchids.
Yellow spots on the leaves of the orchid
Numerous small, yellowish spots covering the entire surface of the orchid leaf in a mosaic, and the slightly dusty underside of the leaf are symptoms of mite feeding. They are very troublesome pests, often living in potted plants. The species most frequently attacking orchids is the orchid spider mite (Tenuipalpus pacificus).
It was spread around the world along with orchid seedlings imported from China. Therefore, when buying orchids, carefully inspect the selected specimen for visible symptoms of mite feeding on the leaves.
Hop spider mite (Tetranyus urticae) causes similar symptoms. The spider mite infestation is favored by high temperature and low air humidity. To get rid of mites from orchids, wash the leaves with lukewarm water with a few drops of dishwashing liquid.
The lower side of the leaf blade can be smeared with vegetable oil. The oil covering the body of the spider mites will limit their access to air. You can also use garlic clove extract or onion husk extract.
Yellow spots on orchid leaves can also be a symptom of feeding scales. Shields are small insects whose body is hidden under a hard shell. They are saturated with plant juices, which at the same time excrete honeydew, i.e. honey dew, which covers the leaf surfaces and favors fungal infection.
The species that often attacks orchids is the citrus plant (Coccus hesperidum), which inhabits plants in greenhouses. Remove scales from orchid leaves mechanically, using a cotton swab soaked in denatured alcohol or water and gray soap.
Mealybugs on orchids are controlled in a similar way. These pests resemble wool fluff and their harmfulness is similar to that of scalefish.
Brown spots on orchid leaves
When dark green, small, slightly recessed spots appear on the orchid leaves, which turn brown and spread over the entire leaf surface, these are symptoms of phytophthora (Phytophthora sp.). It is a fungal disease that develops very quickly in low temperature and high air humidity.
Red, brown spots on orchid leaves are a symptom of rot, caused by fungi of the genus Pythium. In high temperatures and high humidity, Pythium fungi kill orchids within days!
To avoid infection by fungi, you should provide orchids with optimal growing conditions. In attacked plants, remove and destroy all infected leaves.
White spots on the leaves of the orchid
Shimmering metallic silver-white spots on the upper side and black lumps on the underside of orchid leaves indicate the presence of thrips. They are small (3 mm) insects with a variable body color – from white to black. The species inhabiting orchids is the oriental thrips (Thrips palmi).
They are not frequently ascending pests. When you notice the characteristic symptoms of thrips feeding, place blue sticky boards attracting these insects in orchid pots or near them. Spraying is also necessary.
Bright spots on the leaves of the orchid
If you notice round or irregular, slightly sunken, light spots on the orchid leaves, which gradually turn brown and expand into irregular shapes, it means that you are dealing with bacterial leaf spot of phalaenopsis (Pseudomonas cattleyae). Too intensive irrigation of orchids favors the development of this disease.
Cut off the leaves with symptoms of the disease with a sharp tool right next to the root. Leave cut wound to dry and then transplant whole plant into a new pot and fresh substrate. Limit watering and sprinkling the plant. Avoid soaking the leaves when watering as the bacteria travel with the water.
