Types

• Many fungal diseases cause visible fungus or mold to grow on plants. Common diseases include powdery mildew, a disease that afflicts trees, turf, vegetables and ornamentals. Numerous rusts infect various plant species, producing visible fungus on the plants. Cankers and galls caused by fungal infections form on trunks and branches. Wood rots often cause mushrooms to emerge from trunks and branches.
  
  

Effects

• Fungi don't require a wound in order to enter a plant but use physical pressure and enzymes to force their way inside. Fungi extract nutrients from the plant's cells, at best weakening them. Fungal infections vary in their severity, with some, like powdery mildew, killing the plant and others, like sooty mold, causing few to no severe symptoms.
  
  

Prevention/Solution

• Properly planted and maintained plants stand a far better chance of resisting disease, according to the University of Missouri Extension. Many fungal diseases rely on dampness to spread to plants, so correctly spacing plants, keeping them pruned to allow for light and air penetration and watering in the morning to give foliage a chance to dry can help to prevent common diseases like powdery mildew.