Several fungi in the genus Ascochyta can infect canola. The pathogens are disseminated by splashing water, wind, and movement of contaminated seed, and overwinter in infested crop debris and seed.
Infected plants exhibit dark, sunken lesions that soon take on a concentric ring appearance. Small, dark fruiting bodies called pycnidia are produced inside the lesions. Stem lesions often lead to girdling of the stem and plant tissue death above the point of infection. On pods, the lesions usually are circular with a darker border and they often display concentric rings and fruiting bodies inside the lesions also. Some infected seeds have dark spots /areas on the seed surface and often they are shriveled. The disease can reduce both yield and seed quality.
No biological control strategies have been developed for Ascochyta leaf spot.
Plant only high quality seed free from the Aschochyta blight pathogen. Practice a three- to four-year rotation to non-hosts such as small grains. Eliminate canola residues, volunteer, and cruciferous weeds to reduce pathogen survival and overwintering.
Chemical controls are most effective when combined with sound cultural practices. Neem oil is not highly effective.
Product List for Ascochyta Leaf Spot:
Pesticide |
Rate per Acre |
Application Frequency |
Remarks |
Azoxystrobin |
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Quadris |
6.2-15.4 oz |
7-14 days |
Maximum of three applications (27 oz); Beginning applications at 10-25% bloom; Do not make application past 95% petal fall; |
Boscalid |
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Endura |
5-6 oz |
21 days |
Maximum of two applications per season; also provides white mold suppression |
Neem |
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Trilogy |
1% solution |
7-14 days |
Apply in 25 to 200 gallons |
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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: Canola and Mustard, Disease, Ascochyta Leaf Spot
Date: 12/30/2004