The disease usually damages the trunk, branches and leaves, rarely damages the fruit, and also attacks seedlings in the nursery. Symptoms on the leaves: the lesions are round spots about 3-5mm, growing slightly above the leaf surface, looking like a layer of smooth velvet, gray-green or red-brown in color, when the lesions turn gray-brown. When conditions are suitable, the lesions spread rapidly, sometimes as large as a fingertip, on the underside of the lesions can see necrotic leaf tissue and algae growing through, red-brown in color. Severe disease, on the leaves there are many dense spots, covering the entire leaf surface. The disease often appears on mature leaves.

Symptoms on the trunk and branches: The disease often damages the main trunk or old branches inside the canopy. The first lesions are small green spots, round or oval in shape, then gradually grow into patches. The lesions have a layer of fine moss-green silk, and the middle of the lesions is red-brown. Severe disease gradually spreads to the upper branches, sometimes spreading to the fruit. The disease damages the leaves, causing them to become rough and hard, greatly affecting the ability to photosynthesize, stunting the plant and causing poor growth; damages the trunk and branches, causing the bark to crack and dry.

The source of the disease is easily found in nature and spreads strongly because the algae Cephaleuros virescenns is a polyhost, parasitic on many types of plants. Through practical observations, the disease develops strongly in dense, unventilated, poorly cared-for gardens, gardens sprayed with a lot of foliar fertilizers or in old tree gardens. During the rainy season, especially during the months of continuous storms and rains, conditions are favorable for the development of algae spot disease.

Biện pháp phòng trừ:

To manage algae spot disease, gardeners should mainly apply preventive measures:

– Care should be taken to ensure healthy growth of the tree, adequate watering during the dry season and good drainage during the rainy season.

– Every year after harvest, the garden should be cleaned, old branches, diseased leaves, and branches in the canopy that are not capable of bearing fruit should be removed to create ventilation for the garden.

– The garden should be planted at a moderate and reasonable density, not too dense.

– Fertilize adequately and balanced, avoid excessive nitrogen fertilization and especially do not spray foliar fertilizer periodically. Increase organic fertilizer application to improve the soil, limit factors that are unfavorable to plant growth.

– Regularly visit the garden when detecting algae spot disease appearing on the leaves Sulfex 80WG to spray on leaves and wet branches.

This article was written by: Marketing Department – Agriculture Department – Vinhthinh Biostadt Company

Technical advice: 0915 446 744

Fanpage: Wokozim- Organic biological fertilizer

Youtube: Wokozim Vinh Thinh Biostadt

App: VTB GROUP