Ascochyta blight is caused by the fungus Ascochyta fabae f. sp. lentis. Ascochyta blight is currently is the most common disease of lentils in the northern hemisphere. Infection is initiated by sexual spores (ascospores) forcibly discharged up in the air from specialized fruiting bodies (asci) and can move several miles via wind currents. Asexual spores are produced during the season from fruiting bodies (pycnidia) on actively growing plants. These spores exude out of the pycnidia in very high numbers and move short distances via rain splash and wind. Spores germinate and infect lentil optimally when temperatures are mild (68 to 77ºF) and free moisture is present. The pathogen survives between lentil crops in and on infested seed, crop residue, and volunteer lentil.
Ascochyta blight symptoms include light gray to tan spots that often have darkened borders. Within these lesions small, black fungal bodies can be easily observed with the naked eye. Spores are released from these bodies during moist periods and are spread by splashing rain to previously unaffected tissue. During wet periods, the lesions may coalesce and result in premature leaf death. With severe disease pressure, stem tips may wilt, turn brown and cause the crop to appear blighted. Pod and seed infection can occur before or after swathing, resulting in brown to purple seed discoloration and shriveling. Wet conditions following swathing may result in significant loss in seed quality, which can reduce the crop to feed value. Yield losses of 50% have been reported.
Biological control strategies have not been developed for Ascochyta blight of lentil.
Plant seed free from the Aschochyta blight pathogen. Practice a three-year or longer crop rotation to nonhosts such as small grains or corn. Eliminate crop debris and volunteer lentil by deep tillage to reduce pathogen survival. Varieties vary widely in their reaction to Ascochyta blight, and resistant or tolerant varieties should be planted if available.
Chemical controls are most effective when integrated with sound cultural practices.
Common/ Trade Name |
Product per Acre |
Application Frequency
|
Remarks |
|
Boscalid |
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|
Endura |
6 oz |
7-10 days |
Maximum of 2 applications or 22 ounces per season; 21 day phi |
|
Strobilurin |
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|
Amistar |
2-5 oz |
7-14 days |
Maximum of 4 applications per season; Rotate with fungicides with a different mode of action; 0 day PHI |
|
|
Headline |
6-9 fl oz |
7-14 days |
Maximum of 2 applications and 18 oz per season; 21 day PHI |
|
|
Quadris |
6.2 – 9.8 fl.oz |
7-14 days |
Maximum of 6 applications per season; Do not apply more than three applications before rotating to a fungicide with a different mode of action; 0 day PHI |
|
Seed Treatment |
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|
Gustafson LSP |
14 fl oz/100 lb |
-- |
Seed treatments reduce surface contamination |
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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: Pulse Crops, Disease, Ascochyta Blight, Lentil
Date: 04/02/2007