Symptoms: The lesion is round or slightly rounded, 3-5mm in size and raised slightly above the surface of the branch, due to the growth of mosses, which looks like a soft, yellowish-green velvet layer.After the lesion grows wider, when the diameter reaches more than one centimeter and turns to yellowish brown, the middle of the lesion is covered with dark yellow.In young shoots, the infection of algae can create cracks that make branches susceptible to other secondary diseases.
2. Causes, conditions for development of the disease:
– Disease caused by algae: Cephaleuros virescens caused, this algae is quite common in many plants such as durian, citrus, persimmon, coffee ….Diseases reduce the photosynthesis of plants, making plants developed poorly.
– Red algae grow in conditions of heavy rain, wet. The algae appear mainly in the lower layers where there is lack of light.
– Fertilizer, irrigation. Create ventilation in the garden by means of pruning.