Alternaria Leaf Spot of Geranium

Disease Information

Alternaria Leaf Spot

Alternariaalternata

Symptomsand damage

 Usually first evident on the lower leaf surface as small, raised, water-soaked areas; these spots quickly develop into brown, zonate, sunken spots; these can be confused with the spots associated with Bacterial Blight but the Alternaria spots tend to be larger in size; additionally, under conditions of high humidity, dark brown fuzzy spore masses of the fungus cover the Alternaria spots;

Management

 • Practice good sanitation by using a clean house and equipment and a sterile, welldrained medium

• Use disease-free cuttings

• Avoid overhead irrigation

• Rogue and remove symptomatic plants

 • Fungicides: among those registered for use are iprodione, thiophanate-methyl plus iprodione, mancozeb, chlorothalonil, thiophanate-methyl plus chlorothalonil, azoxystrobin, and fludiononil



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