Ceratiomyxa blight

The disease is caused by Ceratiomyxa fruticulosa, a member of the Ceratiaceae family. These organisms are slime molds, biologically distinct from true fungi. While they are primarily saprotrophic, consuming bacteria and organic debris, their ability to colonize the surface of living plants under high humidity can lead to reduced plant vigor by blocking respiratory pathways.

This condition predominantly affects plants in nurseries, greenhouses, and low-lying, damp environments. It targets decomposing mulch, bark, and the surface of plants that are constantly exposed to moisture. It is particularly prevalent on herbaceous plants and woody shrubs that suffer from inadequate air circulation near the base of the stem.

Signs of infestation include the appearance of delicate, coral-like or comb-shaped white to yellowish outgrowths on the plant surface. These structures are the fruiting bodies of the slime mold. Unlike typical powdery mildew, these structures are often gelatinous or slimy to the touch and can rapidly expand across the surface of the plant when moisture is abundant.

Development is entirely dependent on environmental factors, specifically high relative humidity and temperatures ranging from +15°C to +22°C. These conditions trigger the emergence of the plasmodium stage, which moves across the surface. Stagnant air and wet surfaces provide the necessary nutrients and medium for the organism to complete its reproductive life cycle.

Prevention and control strategies focus on sanitation and moisture management. It is essential to remove rotting organic matter from the vicinity of crops and improve airflow to reduce surface moisture. Chemical controls are rarely necessary if the environment is kept dry. Improving drainage and thinning dense canopy foliage is often sufficient to stop the spread of Ceratiaceae in agricultural settings.