Holcus Leaf Spot of Corn

Holcus leaf spot of corn

Holcus leaf spot is caused by the bacteria Pseudomonas syringae pv. syringae. Holcus leaf spot usually does not cause major losses. Leaf spots are initially oval to irregular, dark green, water-soaked at the margins, and may have a light brown border. Later, lesions dry out and turn light tan, usually without a border. The dry lesions have a papery texture.

Holcus leaf spot often follows warm (77-86°F), rainy weather early in the season. Holcus leaf spot lesions with water soaked edges. Image: D. Mueller

Holcus leaf spot lesions may have a light brown border. Image: A. Robertson

Most hybrids have adequate resistance. Other management practices are rarely warranted and fungicides are not effective against this bacterial disease. 

Gallery Images: K. Wise, D. Mueller, and A. Robertson

Related Articles

Southern Corn Leaf Blight of Corn

The pathogen that causes southern corn l...

Goss's Wilt of Corn

Goss's wilt of corn is caused by a bacte...

Head Smut of Corn

Head smut of corn forms on the tassels a...

Tar Spot of Corn

Tar spot can cause severe yield loss on...

Northern Corn Leaf Spot of Corn

Northern corn leaf spot, also known as C...