As a Dendrobium orchid, I am a resilient and diverse member of the plant kingdom, but my succulent pseudobulbs, tender new growths (keikis), and sweet nectar can attract a host of unwelcome visitors. From my perspective, an infestation is a direct attack on my vitality, draining my resources and leaving me vulnerable to disease. Here is a detailed account of the common pests that afflict me and the treatments that can restore my health.
I often feel the subtle pinch of aphids clustering on my soft new shoots and flower buds. They pierce my tissues to siphon my sap, causing my leaves to curl and become sticky with honeydew. This sticky residue then attracts sooty mold, which blocks my sunlight and hinders my photosynthesis. Scale insects are even more insidious. They appear as small, brown, waxy bumps attached firmly to my pseudobulbs and the undersides of my leaves. They latch on, creating a protective shield, and slowly drain my fluids, leading to yellow spots and a general decline in my vigor.
Treatment: For a light infestation, a strong jet of lukewarm water can physically dislodge aphids. For both pests, wiping my leaves and pseudobulbs with a soft cloth or cotton swab dipped in isopropyl (rubbing) alcohol is very effective at dissolving their protective coatings and killing them on contact. For larger outbreaks, horticultural oil or insecticidal soap sprays, applied thoroughly to all surfaces, will suffocate the pests without causing me undue harm.
Spider mites are tiny arachnids that are almost impossible to see until their damage is done. I feel their presence as a fine, silky webbing, especially on the undersides of my leaves. They feed by piercing individual plant cells, leaving behind a stippled pattern of tiny yellow or white dots. If left untreated, my entire leaf can turn yellow, dry up, and drop. Thrips are another minute threat. They rasp the surface of my tender buds and young leaves to feed, resulting in distorted growth, streaked or discolored flowers, and silvery scarred patches on my foliage.
Treatment: Increasing humidity around me is a great deterrent, as spider mites thrive in dry conditions. Regularly rinsing my leaves can wash away a significant portion of the population. Insecticidal soaps and horticultural oils are again the preferred treatment, needing thorough application to reach these hidden pests. For severe, persistent cases, miticides specifically labeled for spider mites may be necessary.
Mealybugs appear as small, white, cottony masses in the tight spaces between my pseudobulbs and at the base of my leaves. Like aphids and scale, they suck my sap and excrete honeydew. Their feeding weakens me significantly and can introduce viral pathogens. Fungus gnats are less damaging to a mature plant like me, but their larvae in the potting medium can feed on my tender young root tips, hindering my ability to uptake water and nutrients.
Treatment: Mealybugs can be treated with the same isopropyl alcohol swabs and insecticidal soap sprays as other sap-suckers. For fungus gnats, the key is to let my potting medium dry out more between waterings, as the larvae cannot survive in dry conditions. Sticky yellow traps placed near my base will catch the annoying adult gnats and help monitor the population level.
