How to prevent and treat black rot of Cattleya

Cattleya black rot symptoms

The symptoms of black rot are more common on the leaves. Many tiny purple-brown wet spots appear on the affected leaves, and irregular spots appear on the lower surface of the leaves, which then gradually spread. The diameter of the lesions reaches 3 cm, and some can even reach 7-8 cm. Larger lesions turn dark brown or black, and will seep out water if squeezed hard, while old lesions will turn dry black; then the leaves will become soft and black, and soon begin to rot. In severe cases, the leaves of the entire plant will turn black and wither.

Cattleya black rot disease

The pathogen overwinters in the diseased part residues as mycelium and conidiophores and is spread by splashing rain and contaminated planting materials and running water. The disease begins to occur at 20 ℃ to 25 ℃, and the outbreak period is from June to September every year. Repeated infection may occur many times. At 25-28 ℃, the disease spreads rapidly, the pathogen spreads very quickly, and the damage is serious. The disease is more common in southern regions from August to October . This disease can usually be caused by compacted soil, dense planting, poor air circulation, poor fertilizer and water management, excessive nitrogen fertilizer or direct watering. The disease is more serious especially when there is frequent rainfall at the turn of summer and autumn and when there are storms or continuous autumn rains.

Cattleya black rot prevention and control methods

Remove dead leaves and diseased debris, and cut off diseased sections of live leaves.

To improve the permeability of the garden, the potting soil should be slightly acidic and fertile, use pond mud, tree bark and other planting materials, add fertilizer, pay attention to shade, and avoid watering.

Use spraying to protect new leaves, spray disease-killing chemicals, maintain ventilation, and avoid moisture.