Cephaleuros virescens and C. parasiticus

Fungal Disease

Cephaleuros virescens and C. parasiticus

Fungal Disease

Cephaleuros virescens and C. parasiticus

Fungal Disease

Cephaleuros virescens and C. parasiticus

Fungal Disease

Cephaleuros virescens and C. parasiticus

Fungal Disease

Algal leaf spot affects various tropical fruit species, and while often of minor concern on most hosts, it can significantly harm guava. On guava, the disease leads to necrosis, defoliation, reduced fruit quality, and crop loss, as well as diminished photosynthesis and plant vigor. The disease thrives under poor environmental conditions such as inadequate soil management, overcrowded trees, and weed pressure, and its severity can be increased by the presence of insects, mites, or other foliar pathogens.

Symptoms

• Initial dark-brown specks on leaves enlarge into circular lesions with ash-colored centers and dark-brown margins.
• Some cultivars show spots with yellow halos.
• Orange, rust-colored tufts develop as the disease progresses.
• A dead grayish-white to dark crust remains after scraping off the spots, which can merge to form large patches.
• Twigs and branches can also be affected, leading to bark cracking due to pathogen growth.

Causal Organism

• The disease is caused by parasitic green algae, Cephaleuros virescens and C. parasiticus.