Root rot of carrot
the disease forms circular to irregular spots on the leaves that vary in colour from grey to almost black. The spots appear to be sharply defined, but under [...] fungus develops at temperatures ranging from -3°C to 25°C, with an optimum around 18°C. Lesions are dark brown to black, moist, mostly circular spots 0.5 [...] The pH for growth, sporulation, and spore germination ranges from 3.4 to 7.1 (optimum 4.2–4.7). This affinity for acidic conditions may explain the concentration