Cosmos flower frequently suffer no severe issues, however they may experience aphids, spider mites, thrips and whiteflies. Their feeding habits result in curled leaves or reduced growth. Powdery mildew or root rot can occur in wet weather or in wet, poorly drained soil. Most problems can be avoided by regularly examining plants, increasing air circulation, preventing overhead watering and discarding infected plant material. Aphids can also be controlled with natural predators, such as ladybugs.
