Red mould and fungi namely occur on trees with damp wood. Trees that are particularly susceptible to fungi, like mushrooms, can then cause moulds and other parasitic fungi species to grow on the tree. These growths can act as parasites, taking the tree's water and nutrient resources.
Heart rot is a fungal disease that attacks damp tree wood, like those suffering from water rot. Maple tree types, especially silver maple and boxelder, are susceptible to wood decay and the proceeding heart rots. The red mould fungus on the tree resembles a wide mushroom top and is bright cherry red or blood red. The bright red colouration is most often found on boxelder tree trunks.
Beefsteak fungus (Fistulina hepatica) infects deciduous tree roots and trunks. The mould fungus is called beefsteak after the fungus's resemblance to a sliced open beefsteak tomato, though much less appetizing. The fungus acts like a parasite on the tree, stealing nutrients from the tree. This then produces wood rot, which can damage the tree from the inside out.
Powdery mildew infections reduce a tree or other plant's photosynthesis process and decrease leaf water retention. Flowering dogwoods are particularly susceptible to powdery mildew, a causal fungus. The infected dogwood trees display small, blood-red splotches on the tops of otherwise healthy-looking green or red leaves, depending on whether its spring or fall. The splotches develop into brown, dry, dead areas on the leaf. A white, dusty fungal growth, which typically indicates powdery mildew on a tree, is not as obvious on dogwood.