KWS

Alternaria leaf spot

Causal agent: Alternaria tenuis
Symptoms: Beginning at the edge or tip the leaves become brown in the intercostal fields and die. A black, velvety coat develops on the tissue (bearer of conidia).
Epidemiology: The causal agent is a parasite which infects first those leaves being primarily damaged by other causes, e. g. due to mechanical damaging of the leaves after virus infections, drought damage or lack of nutrients.
Economic importance: As the economic importance is only secondary, no control measures of the disease are needed.

KWS