Aphids show up on almost all plants, especially tender greens. In specialty stores, you can buy anabasine or nicotine sulfate. Use that solution (follow the package dilution instructions) to spray the plant on your balcony, then keep it outside for 3 to 4 days before bringing it back indoors. Wash the plant thoroughly afterward. A strong home remedy is a tincture made from tobacco, onion skins, or garlic (10 grams per liter of water). Boil it in the evening and let it steep overnight. In the morning, spray the mixture on the plants.
True scale insects thrive on houseplants with lush foliage, such as palms, laurels, cacti, citrus trees, oleanders, and ficuses. You can only eliminate them manually because they attach themselves to the foliage. Soak a cloth in a tobacco solution, add a bit of soap (to help the solution stick), and carefully wipe each leaf.
Powdery mildew most commonly appears on roses. Spray the bush with a 3 percent solution of ferrous sulfate (30 grams per liter of water) before the buds open. If a white coating appears on the leaves, rinse them weekly with a 0.5 percent solution of copper sulfate (5 grams per liter of water).
Wash the stems and leaves with water mixed with laundry detergent (one tablespoon per liter of water).
