Identification and Life Cycle
· Dwarf bunt is caused by the fungus Tilletia controversa Kűhn.
· The fungus can infect wheat, barley, rye, and several wild grasses.
· The pathogen can survive in soil as long as 10 years as teliospores.
· The fungus grows optimally at 37 to 46ºF under snow cover and infects seedlings AFTER emergence, at or near the soil line.
· Plants in the 2-5 leaf stage are the most susceptible.
· This is a disease of winter wheat in areas subjected to prolonged periods of snow cover.
Plant Response and Damage
· Diseased plants are stunted and only grow one-fourth to one-half as large as normal size, and typically have more tillers than healthy plants.
- Common bunt looks similar, but the plants are generally not stunted.
· Bunted heads are slender, remain green longer, and have glumes that spread apart.
· Bunt balls are evident in the head and are approximately the size and shape of kernels. They will have a fishy odor due to the chemical trimethylamine that is produced by the fungus.
· Dark spore clouds are sometimes produced at harvest in fields severely affected by dwarf bunt. These clouds are flammable and can combust during harvest.
· The disease reduces grain yield, quality, and marketability.
Management Approaches
· Resistant cultivars
· Plant clean seed. Do not save dwarf-bunt infected seed.
· Fungicide treatment
· Cultural management
Biological Control
· No biological control strategies have been developed for dwarf bunt.
Cultural Control
· Resistant varieties offer the most practical means of control for dwarf bunt.
· Planting in warm soils often helps to avoid infection.
Chemical Control
Product List for Dwarf Bunt:
Pesticide |
Product per 100 lbs seed |
Remarks |
|
Difenoconazole |
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|
Dividend XL RTA |
10 fl oz |
Seed treatment; 55 day PHI |
|
Dividend Extreme |
4 fl oz |
Seed treatment; 55 day PHI |
|
The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Small Grains, Disease, Dwarf Bunt
Date: 2/6/08