Species Name: Alternaria tenuis Nees
Yellow, dark brown to black circular leaf spots in concentric rings found on leaves.
Overwinters as mycelium/spores in infected plant debris. Spores may be disseminated during rains to susceptible plant when they germinate directly through wound. Forms conidia that are further spread to cause infection
Apply systemic fungicide to affected trees. Use resistant trees when planting
Growth stage: Mature tree
Disease name: Alternaria leaf spot
Synonym: Alternaria alternata (Fr.) Keissl.
Host name: Alnus nepalensis
Host common name: Nepalese Alder
Affected part: Leaves