Alternaria

Pathogen: Alternaria spp.

Hosts: There are several species of Alternaria that are pathogenic on perennials. Together they have a wide host range including Aster, Calendula, Coreopsis, Dianthus, Gypsophila, Helianthus, Iris, Ligularia, Pelargonium, Platycodon, Shasta, and Stokesia.

Symptoms: Dark colored leaf spots, lesions may have concentric rings within the lesion. Spots may coalesce, resulting in blighting of foliage. Petals of some plants may be infected. Flower buds of Dianthus can be rotted.

Spread: Spores are produced on the plant surface and are spread by splashing water, air movement or by moving infected plant material.

Management: Maintain adequate plant spacing to allow for good aeration to reduce humidity levels around plants. Alternaria spp. require leaf wetness for germination and infection; reduce durations of leaf wetness periods with good timing of overhead irrigation. Regular fungicide applications will likely be necessary to reduce losses on especially susceptible hosts.

LiguariaBottomOfLeaf-300x225
Alternaria on Liguaria Bottom of Leaf
LiguariaTopofLeaf-300x225
Alternaria on Liguaria top of leaf

Other Documents in this Series

You Might Also Be Interested In

Accessibility Questions:

For questions about accessibility and/or if you need additional accommodations for a specific document, please send an email to ANR Communications & Marketing at anrcommunications@anr.msu.edu.

Tag List
  • msu plant & pest diagnostics,
  • plant pathogen

About

Michigan State University
  • Spartans Will.
  • © Michigan State University

MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential.

Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Quentin Tyler, Director, MSU Extension, East Lansing, MI 48824. This information is for educational purposes only. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.

The 4-H Name and Emblem have special protections from Congress, protected by code 18 USC 707.

We comply with the Federal Trade Commission 1998 Children’s Online Privacy Protection Act (COPPA).