Houseplant Pest And Disease Control
by Pamela Kock

Keeping your plants healthy isn't all about giving them adequate light and water. Just like plants that live outdoors, your houseplants may fall prey to pests and diseases. Some varieties are more prone to certain ones than others - in fact certain plants are notorious for susceptibility. 

Since your plants are in your living space, often in close quarters with pets and children, it's best to avoid using toxic chemicals to get rid of the problem. If a plant is badly affected, it's often wiser to simply get rid of the plant. At the very least, the "patient" should be isolated to avoid infecting other nearby plants. 

Pests and diseases tend to invade when conditions are not ideal. For example, the Red Spider Mite thrives on almost any plant when the air is warm and dry. Fungus gnats love it when plants are overwatered, and parts of the plant may rot. 

Red Spider Mites are very common. The leaves will look paler or darker than normal, and they produce white webbing between the leaves and stems, and if you look closely, you can see them crawling around. Once these creatures take hold, the only way to get rid of them may be to get rid of the plant. Ivy seems to be the most susceptible to this menace. If your plants like humid conditions, mist them often and keep them away from heating vents. 

Aphids are most common on flowering plants. They are usually green and can be found underneath leaves, especially the newer ones, and leave behind sticky sap. Most commercial houseplant pest sprays can control them. Scale insects are small brown discs on the undersides of leaves. Mealybugs look like little pieces of white fluff. Sprays will not affect either of them, but you can take them off with a cotton swab or damp cloth. 

Whiteflies are tiny insects that look like moths. They fly away when the plant is shaken. Like Aphids, whitefly larvae hide under leaves and suck their sap, leaving a sticky residue behind. They are very contagious and hard to control. Isolate the plant immediately and spray every three days with a houseplant pest spray containing permethrin. 

The insect I'm currently fighting in my house is the Fungus Gnat. They are very difficult to avoid especially around plants that enjoy moist, humid conditions because they thrive in damp soil. Fortunately, they rarely affect the plant, but they are annoying to have flying around your home. Watering with an insecticide solution may help, but the easiest way to discourage them may be to water less frequently. You might also try "fluffing up" the top of the soil around the plant so the top dries more quickly. 

Diseases are not very common among houseplants. Many conditions mistaken for diseases are caused by improper plant care, such as rotting crowns and stems from overwatering. Mold, fungi, and mildew do occur, but they can usually be prevented by maintaining the right conditions. If you see fluffy mold, brown spots, or powdery deposits on the leaves, remove the affected leaves and spray the plant with fungicide. 

Many people like to take their houseplants outdoors during the summer, and quite a few plants thrive on it. However, this practice may introduce them to pests, including some not usually found on houseplants. Inspect them carefully when bringing them back indoors, and isolate them from the rest of your plants until it's certain nothing else came in with them. Isolation and observation are a good idea when bringing any new plant into your home. 

The pests and diseases that may occur are common, but usually not hard to prevent with proper care. The best way to keep these invaders at bay is to give your plants the environment they need and examine them frequently.