Grey Mould: Fungal Disease | Treatment Guide

Rust fungi (Pucciniales) are fungal diseases that form rust-colored, usually orange to brown pustules with powdery spore dust on leaves, stems, or fruits. Typical symptoms include small spots that develop into cushions or rings; leaves turn yellow, curl, and drop prematurely. The fungi spread primarily in damp weather and dense foliage. Many ornamental and crop plants are affected, frequently including roses, mallows (hollyhocks), pears (pear rust), and currants. Some rust fungi require two host plants for their life cycle, such as pear and certain juniper species.

Taphrina wiesneri is a fungal disease affecting cherry trees (Prunus species, including sweet, sour, and ornamental varieties). The fungus overwinters in buds and bark, infecting young leaves and shoots during cool, wet spring weather. Infected leaves become thickened, puckered, and curled, often displaying reddish or yellow blotches and a fine whitish bloom on the surface. Severely affected leaves may drop prematurely. Small twigs can develop 'witches' brooms,' which are dense clusters of weak, distorted shoots.

Powdery mildew is a common fungal disease caused by various fungi species including Erysiphe, Podosphaera, Oïdium, and Leveillula. It affects over 10,000 plant species worldwide. The disease thrives in warm, dry climates with high humidity and appears as a distinctive white powdery coating on plant surfaces.

Root rot is a serious fungal disease that affects the root system of plants, causing them to decay and die. It is primarily caused by overwatering, poor drainage, or soil-borne fungi such as Pythium, Phytophthora, Rhizoctonia, and Fusarium. The disease thrives in waterlogged conditions where roots are deprived of oxygen, making them susceptible to fungal infection.