Photo: Dr. Wayne Nishijima
Spots appear on the leaves. Fruit of guava may also be affected. Algal leaf spot affects avocado, guava, pepper, magnolia, kava, tea, coffee, oil palm, vanilla, mango, breadfruit, and cacao. Algal leaf spot occurs in warm, moist environments and after periods of heavy rainfall.
Algal leaf spot on Avocado
Photo: Dr. Scot C. Nelson, CTAHR
Algal leaf spot or Cephaleuros is a plant-parasitic green algae and is generally harmless though unsightly. Some Cephaleuros occurs on the upper leaf surface and is characterized by a raised, velvety, orange or brown appearance. Algal leaf spot can cause full necrosis of the leaf tissue, leaving brown dead spots. It can also appear as bright orange spots on the underside of the leaves. On some guava trees, a yellow halo encircles the lesions.
Kendal Lyon, Hawaii Island Master Gardeners