• European palm trees (Chamaerops humilis) are popular with many home gardeners due to their compact size and cold hardiness. Often called fan palms and grown in containers, these palm trees have attractive, fan-shaped leaves and are resistant to insect pests and diseases. In fact, there are no known serious diseases that affect European palm trees, although there are some less-serious ones.
  
  

Bacterial Diseases

• European palm trees are cold-tolerant, but a deep freeze can activate bacteria that lives inside a normally healthy palm tree, killing even the bud. A heavy freeze often kills all of a European palm tree but leaves the protected bud alive. If the bud dies soon after, however, it has been infected by bacteria activated by the freezing temperatures. There is no way to know for sure until after the bud either dies or blooms.
  
  

Leaf Spot

• Spider mites are usually the indirect cause of leaf spot on potted European palm trees, especially those grown indoors. The honeydew they leave behind on European fan palms is quite sticky. Fungus spores, borne on the wind, can stick to the honeydew and infect the leaves of the palm tree, causing them to become spotted. This will not kill the palm tree, but it does make it unsightly.
  
  

Lethal Yellowing

• Lethal yellowing is a bacterial disease transfered by the planthopper, a chewing insect. Premature fruit drop may occur, followed by yellowing of the leaves of the palm, starting with the oldest, or lower leaves. Over time, the leaves wither, droop and turn brown, eventually falling off the palm tree. The disease moves up the tree and will eventually kill the bud. Once this happens, the tree is officially dead. Luckily, the disease is not cold-hardy, meaning that once cold weather hits, the bacteria in the tree is killed, and the European palm tree will survive the infection. For less-cold hardy palms, however, there is no happy ending.