I have several Phalaenopsis Orchids. One has a sticky substance on the bottom side of the leaves; can you tell me what this is? It is blooming and has also produced new leaves. None of the others have it.
Thank you for your response.
If the secretion is clear and the plant is healthy otherwise, it is most likely a normal sugary substance that is of no concern.
However, if the plant, on careful observation, shows any signs of small white spots (mealybugs), aphids, or mites then there is a problem as insects can feed on this sticky sap. As well, the insects themselves produce a sticky substance, so its important to have a really good look to ensure no evidence of infestation. A magnifying glass can be useful in early detection and treatment of these damaging pests.
The St. Augustine Orchid Society has a helpful site with great photos, as an additional resource.