Corn Leaf Diseases: Grey Leaf Spot

Excerpt from Agronomy Guide for Field Crops (Chapter 3)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Incidence
2. Appearance
3. Disease Cycle
4. Management Strategies
5. Updates on Corn Leaf Diseases: Grey Leaf Spot
6. Related links...

Incidence

Grey leaf spot has been increasing in the surrounding Great Lakes states and has recently been developing in Southwestern Ontario. Significant losses can occur from this disease under warm, wet and humid conditions.

Appearance

Symptoms develop on the lower leaves soon after tasselling. The disease has unique, elongated (2-7 cm (1-3 in.) long), narrow, light-tan, rectangular lesions. These lesions run parallel to the leaf veins. As the lesions mature, they become grey and join, killing or blighting entire leaves.

Disease Cycle

Grey leaf spot is most problematic when corn follows corn in fields with a considerable amount of corn residue. The fungus survives as fungal strands (mycelium) in corn residue. Spores produced on the residue are dispersed by wind and rain splash. Warm, humid weather helps spore and disease development.

Management Strategies

Some hybrids are tolerant to the disease, and crop rotation and tillage will reduce inoculum levels in surface residues. In reduced tillage systems, rotation and hybrid resistance are necessary. Chemical control is not usually economical in field corn.

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Updates on Corn Leaf Diseases: Grey Leaf Spot

• Field Crop Protection Guide - Publication 812
  • Corn: Grey Leaf Spot

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Related links...

• Diseases
• Corn

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