Plumeria Rust

• Plumeria flowers have a lovely frangrance.Jupiterimages/Photos.com/Getty Images
  
  Plumeria rust is the most common fungal disease of frangipani. It appears close to the end of the growing season when the plants are about to lose their leaves for winter. It starts as small, yellow-orange, raised pustules on the undersides of the leaves. The top surface of the leaf shows yellow spots, which gradually enlarge to become gray or brown, sunken, and angular. If not controlled, the disease can cause 100 percent premature leaf drop. Commercial fungicides containing mycobutanil and azoxystrobin are used in larger operations, but liquid copper or neem oil are commonly used in the home garden. Treatment may delay leaf drop by three weeks to a month, which strengthens the plants for healthier growth the following year.
  
  

Black Tip Fungus

• Black tip fungus strikes in the spring, when temperatures are under 60 degrees Fahrenheit. It is hard to control once established. This disease thrives in shady, wet and cool areas. Growing frangipani in full sun and not watering at night helps prevent black tip fungus. When a plant is attacked by this fungus, the growing tip turns black and stops growing. The fungus then travels down the stem and spreads into the entire plant. Spraying with liquid copper, neem oil or fungicides containing azoxystrobin or mycobutanil can control the disease if applied early. If treatment is unsuccessful, pruning off the affected tips to healthy wood is the only way to save the plant.
  
  

Powdery Mildew

• Powdery mildew presents itself as a white powder on the leaves of frangipani. It is a sure sign that a plant is not getting enough air circulation. Liquid copper or neem oil can be used to treat it, but if the air circulation is not increased, it will return.
  
  

Sooty Mold

• Sooty mold is a black, powdery fungus that appears on frangipani leaves. It grows on the secretions of thrips, aphids and whiteflies. Once the plant is rid of the pests, the fungus will eventually dry up and fall off, but if you don't want to wait, liquid copper or neem oil will kill it quickly. Once it is dead, a strong spray of water will remove it from the plant, or it can be wiped away with a rag soaked in soapy water.