Guide to Head Diseases of Wheat and Barley in Montana

Dr. Mary Burrows, Extension Plant Pathology Specialist, Montana State University

Contents

1. Fusarium head blight (scab) of wheat and barley (Fusarium spp.)
2. Common bunt (stinking smut, covered smut) of wheat (Tilletia tritici or T. laevis)
3. Dwarf bunt (TCK) of winter wheat (Tilletia controversa Kuhn)
4. Loose smut of wheat and barley (Ustilago tritici)
5. Ergot of wheat and barley (Claviceps purpurea)
6. Black chaff of wheat and barley (Xanthomas spp.)
7. Melanism (abiotic)
8. Black point (kernel smudge) (various fungi)
9. Sooty mold (primarily Alternaria, but other fungi can be involved)
10. Acknowledgments

Fusarium head blight (scab) of wheat and barley (Fusarium spp.)

• Symptoms
  • Partial bleaching of the head
  • Brown stems on very susceptible varieties
  • If moist, pink/orange fungal mycelia
• Risk Factors
  • Continuous wheat or barley production
  • Moist conditions at flowering
  • Previous history of scab
• Management
  • Crop rotation, cut irrigation 10 days before flowering and through the flowering period
  • Resistant varieties
  • Fungicides applied at or before flowering

contents

Common bunt (stinking smut, covered smut) of wheat (Tilletia tritici or T. laevis)

• Symptoms
  • Grain kernels replaced with brown masses of spores known as smut balls
  • Fishy smell
• Risk Factors
  • Contaminated seed, often from previous crop
• Management
  • Resistant cultivars
  • Fungicide seed treatment
  • New seed source

contents

Dwarf bunt (TCK) of winter wheat (Tilletia controversa Kuhn)

• Symptoms
  • Grain kernels replaced with brown masses of spores known as smut balls
  • Fishy smell
  • Plants and heads are stunted/dwarfed
• Risk Factors
  • Contaminated seed, often from previous crop
• Management
  • Resistant cultivars
  • Systemic fungicide seed treatment
  • New seed source

contents

Loose smut of wheat and barley (Ustilago tritici)

• Symptoms
  • Grain kernels replaced with green-brown masses of spores covered by a thin membrane
  • Spores disperse within days of head emergence
• Risk Factors
  • Contaminated seed, often from previous crop
• Management
  • Resistant cultivars
  • Systemic fungicide seed treatment
  • New seed source

contents

Ergot of wheat and barley (Claviceps purpurea)

• Symptoms
  • Grain kernels replaced with solid purple-black mass of fungal hyphae called a sclerotia
  • if wet after flowering honeydew (sticky mass of fungal conidia) can be observed on infected heads
• Risk Factors
  • Contaminated seed, often from previous crop
• Management
  • Crop rotation to non-grass crop
  • Tillage to bury sclerotia
  • Clean seed

Caution: Ergot is toxic to humans and animals (ergotism)

contents

Black chaff of wheat and barley (Xanthomas spp.)

• Symptoms
  • Red/brown/black streaks on glumes
  • Watersoaked spots on leaves and/or glumes
• Risk Factors
  • Contaminated seed, often from previous crops
  • Can also be on residue or soilborne
• Management
  • Crop rotation to non-grass crop
  • Tillage to bury residue\
  • Clean seed

contents

Melanism (abiotic)

• Symptoms
  • Red/brown/black streaks on glumes
  • No spots on leaves, although stems or nodes may also be dark
• Risk Factors
  • Stress (particularly heat stress)
  • Variety (genetics)
• Management
  • Variety selection

contents

Black point (kernel smudge) (various fungi)

• Symptoms
  • Glumes, other tissues covered with black, sooty-appearing mold
  • Diseased kernels are discolored, weathered, black at seed ends
  • Embryos often shriveled and brown to black in color
• Risk Factors
  • Warm, moist weather during maturation
  • Delayed harvest
• Management
  • None practical, avoid moisture during crop storage

contents

Sooty mold (primarily Alternaria, but other fungi can be involved)

• Symptoms
  • Glumes, other tissues covered with black, sooty-appearing mold
  • Diseased kernels are discolored, weathered, black at seed ends
  • Embryos often shriveled and brown to black in color
• Risk Factors
  • Warm, moist weather during maturation
  • Delayed harvest
• Management
  • None practical, avoid moisture during crop storage

contents

Acknowledgments

Photos courtesy of MSU Plant Pathology Department slide collection, CIMMYT, and HGCA.

Original July 2009 PDF (2.5MB)

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