Put on a shirt with long sleeves, long pants, chemical-resistant gloves, protective eyewear, shoes and socks and chemical-resistant headgear. Do not touch or apply malathion to your plants without first putting on all of these protective items.
Fill a pesticide or liquid fertilizer sprayer with malathion. The amount of malathion that you need to use varies widely depending on the type of plant that you want to treat. Follow the manufacturer's directions for application rates.
Spray the malathion on the affected plants.
Keep all humans and pets away from the treated area until the malathion has dried, which may take a full day.
Wash the outsides of your gloves before taking them off, then discard any clothing that touched or was sprayed with the pesticide and wash your hands thoroughly after using the product.