Cause Ascochyta rabiei (syn. Phoma rabiei; teleomorph stage: Didymella rabiei, syn. Mycosphaerella rabiei), a fungus that can be carried in and on seed and in infested crop residue. Medicago sativa (alfalfa), Melilotus albus (white sweet clover), Lactuca serriola (prickly lettuce), and Thlaspi arvense (field penny-cress) are reported to be hosts for this fungus while lentil, cowpea, pea, and common bean have been infected in pathogenicity studies. The initial infections on chickpea may be incited by ascospores or conidia produced on infected crop debris, as well as by infected seed. Debris can remain infectious for several years. Ascospores are released in the spring time and can be moved by wind current over distances longer than a quarter mile. The fungus produces dark fruiting bodies (pycnidia) which contain asexual spores (conidia) that are moved by splashing water droplets. Infection and blight develop rapidly on susceptible varieties in the presence of free moisture (rain and dew). Disease is promoted by wet, humid conditions when temperatures are between 41 and 86°F with the optimum temperature for disease development being 68°F. In the field, blight first appears in small patches in lowlands or under sprinkler irrigation. With available moisture and wind or splashing water to disperse spores, the blight may spread throughout the entire field.
Symptoms Leaf spots, stem, and pod lesions are initially chlorotic and turn necrotic. Developing lesions tend to coalesce unless the weather turns dry or hot, causing large brown areas and may result in blight (death) of all aboveground plant parts. The dark colored pycnidia appear in concentric rings within circular leaf and pods spots and within elongated lesions on stems. Stem lesions may fracture the stem. Infected seeds will be small, brown and shriveled.
Cultural control
- Use only clean seed from crops and areas known to be free of blight.
- Resistant varieties such as Sanford and Dwelley (Kabuli types) and Myles (Desi type) are currently available.
- Destroy all infested chickpea residues and volunteer chickpea plants that may harbor the pathogen by deep tillage or by flailing followed by shallow tillage.
- Rotate 3 to 4 years between chickpea crops.
Chemical control
- Treating seed with approved fungicides reduces most surface inoculum but not will rid seed of internal infection.
- Mertect 340-F at 2.04 fl oz/100 lb seed plus a dye. 12-hr reentry.
- Foliar applications can help control disease.
- Aprovia Top (Group 7 + 3) at 10.5 to 11 fl oz/A on a 14-day interval. Do not apply more than two (2) sequential applications or two (2) application per year. Preharvest interval is 14 days. 12-hr reentry.
- Endura (Group 7) at 6 oz/A at the beginning of flowering. Make a second application 7 to 10 days later if disease persists or weather conditions are favorable for disease development. Preharvest interval is 21 days. 12-hr reentry.
- Inspire Super (Group 3 + 9) at 16 to 20 fl oz/A on 7- to 10-day intervals. Make no more than two (2) sequential applications. Preharvest interval is 14 days. 12-hr reentry.
- Proline 480 SC (Group 3) at 5.0 to 5.7 fl oz/A on 10- to 14-day intervals. Preharvest interval is 7 days. 12-hr reentry.
- Strobilurin fungicides (Group 11) are labeled for use. Do not make more than one (1) application of any Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. Do not apply more than two (2) applications of any Group 11 fungicide per season.
- Headline at 6 to 9 fl oz/A at the beginning of flowering or at the onset of disease. Preharvest interval is 21 days. 12-hr reentry.
- Heritage at 3.2 to 8 oz/A on 7- to 14-day intervals. May be applied the day of harvest. 4-hr reentry.
- Quadris Flowable at 6 to 15.5 fl oz/A or Quadris Opti at 1.6 to 2.4 pints/A on 7- to 14-day intervals. Do not apply within 14 days of harvest. 4-hr reentry for Quadris Flowable, 12-hr reentry for Quadris Opti.
- Premixes of Group 3 + 11 fungicides are available for use. Do not make more than one (1) application of any Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. Do not apply more than two (2) applications of any Group 11 fungicide per season.
- Quilt at 14 fl oz/A or Quilt Xcel at 10.5 to 14 fl oz/A on 7- to 14-day intervals for no more than three (3) applications. Preharvest interval is 14 days. 12-hr reentry.
- Quadris Top at 8 to 14 fl oz/Acre on 14-day intervals. Preharvest interval is 14 days. 12-hr reentry.
Biological control
- Stargus at 0.5 to 4 quarts/A on 7- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
References Foresto, E., Carezzano, M.E., Giordano, W., and Bogino, P. 2023. Ascochyta blight in chickpea: An update. J. Fungi 9(2):203. https://doi.org/10.3390/jof9020203.
Harveson, R.M., Markell, S.G., Goswami, R., Urrea, C.A., Burrows, M.E., Dugan, F., Chen, W., and Skoglund, L.G. 2011. Ascochyta blight of chickpeas. Online. Plant Health Progress doi:10.1094/PHP-2011-0103-01-DG.
Wiese, M.V, et al. 1995. Ascochyta Blight of Chickpea. University of Idaho Cooperative Extension System CIS 886.