Physoderma brown spot is caused by the fungal pathogen Physodermamaydis.
Infection occurs in the leaf whorl when water has been present for an extended, warm period.
Disease is limited and does not typically cause economic loss in the Mid-Atlantic.

Identification

Symptoms occur on mid-canopy leaves.
Lesions occur on the stalks and midrib. They are dark purple to black in color (Figs 1-3).
Banding of numerous yellowish-brown lesions across leaves can also be present (Figs 2-3).

Fig 1: Physoderma brown spot lesions on corn stalks and leaves

Fig 2: Physoderma brown spot lesions and lesion banding near and inside the whorl

Fig 3: Septoria brown spot lesions and lesion banding on the leaf surface

Management

Cultural practices like tillage and crop rotation can decrease inoculum load.
Resistant hybrids are available to combat Physoderma brown spot.
Fungicides are labeled for management, but this disease rarely reduces yield and should not require treatment.

References

Crop Protection Network . (2022, January 27). Retrieved from Physoderma Brown Spot of Corn: https://cropprotectionnetwork.org/encyclopedia/physoderma-brown-spot-of-corn

Authors: Madeline Henrickson and Dr. Alyssa Koehler

UD Cooperative Extension

This institution is an equal opportunity provider.

In accordance with Federal law and U.S. Department of Agriculture policy, Cooperative Extension is prohibited from discriminating on the basis of race, color, national origin, sex, age, or disability.