Abstract
A selective medium to detectAlternaria dauci andA. radicina on seed, plant debris and other substrates was developed. Growth and sporulation by most undesired organisms was reduced, but adequate mycelial growth and sporulation byA. dauci andA. radicina was maintained so they could be identified by their unusual mycelial growth or characteristic spores. The medium is based upon carrot leaf extract, which promotes profuse sporulation by both pathogens. Glucose, sodium polypectate and mineral salts further enhanced spore and mycelial production. Streptomycin sulfate and metalaxyl (or mefenoxam), combined with either benomyl or thiophanate-methyl, reduced growth and sporulation of unwanted organisms. There were strong interactions among the fungicides, bactericide, and most other medium components. There were also significant effects on the type of mycelial growth produced by some medium components. If the unique, dark mycelia produced by both pathogens is the desired detection method, the medium components must be optimized for eitherA. dauci orA. radicina because the two fungi responded differently in this regard. All medium configurations allowed both fungi to be identified by their characteristic spores. The sensitivity of theAlternaria dauci-radicina selective medium (ADRSM) to detectA. radicina on carrot seeds was similar to other methods presently in use, but ADRSM was more sensitive than the other methods for detectingA. dauci on infested carrot seeds.
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Andersen, B. and Thane, U. (1996) Differentiation ofAlternaria infectoria andAlternaria alternata based on morphology, metabolic profiles, and cultural characteristics.Can. J. Microbiol. 42: 685–689.
Chen, T.W. and Wu, W.S. (1999) Biological control of carrot black rot.J. Phytopathol. 147: 99–104.
Gambogi, P. (1987) Working sheet No. 4. Carrot, leaf blight and damping off.in: Handbook on Seed Health Testing. 2nd ed. International Seed Testing Assoc., Zurich, Switzerland.
Grogan, R.G. and Snyder, W.C. (1952) The occurrence and pathological effects ofStemphylium radicinum on carrots in California.Phytopathology 42: 215–218.
Hewett, P.D. (1964) Testing carrot seed infected withAlternaria porri f.sp.dauci.Proc. Int. Seed Test. Assoc. 29: 463–471.
Maude, R.B. (1966) Studies on the etiology of black rot,Stemphylium radicinum (Meier, Drechsl., & Eddy) Neerg., and leaf blight,Alternaria dauci (Kühn) Groves & Skolko, on carrot crops, and on fungicide control of their seed-borne infection phases.Ann. Appl. Biol. 57: 83–93.
Maude, R.B. and Shuring, C.G. (1972) Black rot of carrots.Rep. Natl. Veg. Res. Stn. Wellesbourne, Warwick, UK 20: 103.
Meier, F.C., Drechsler, C. and Eddy, E.D. (1922) Black rot of carrots caused byAlternaria radicina n. sp.Phytopathology 12: 157–168.
Neergaard, P. (1945) Danish speciesof Alternaria andStemphylium. Oxford Univ. Press, London, UK.
Neergaard, P. (1977) Seed Pathology, Vol. I. Halsted Press, New York, NY.
Netzer, D. and Kenneth, R.G. (1969) Persistence and transmission ofAlternaria dauci (Kühn) Groves & Skolko in the semi-arid conditions of Israel.Ann. Appl. Biol. 63: 289–294.
Pryor, B.M., Davis, R.M. and Gilbertson, R.L. (1992) Development of a semiselective medium for the recovery ofAlternaria radicina. Phytopathology 82: 1092 (abstr.).
Pryor, B.M., Davis, R.M. and Gilbertson, R.L. (1994) Detection and eradicationof Alternaria radicina on carrot seed.Plant Dis. 78: 452–456.
Pryor, B.M., Davis, R.M. and Gilbertson, R.L. (1998) Detection of soilborneAlternaria radicina and its occurrence in California carrot fields.Plant Dis. 82: 891–895.
Pryor, B.M. and Gilbertson, R.L. (2001) A PCR-based assay for detection ofAlternaria radicina on carrot seed.Plant Dis. 85: 18–23.
Pryor, B.M., Strandberg, J.O., Davis, R.M., Nunez, J.J. and Gilbertson, R.L. (2002) Survival and persistence ofAlternaria dauci in carrot cropping systems.Plant Dis. 86: (in press).
Rotem, J. (1994) The genusAlternaria: Biology, epidemiology, and pathogenicity. APS Press, St. Paul, MN, USA.
Scott, D.J. and Wenham, H.T. (1972) Occurrence of two seed-borne pathogens,Alternaria radicina andAlternaria dauci on imported carrot seed in New Zealand.N.Z. J. Agric. Res. 16: 247–250.
Simmons, E.G. (1992) Alternaria taxonomy: Current status, viewpoint, challenge. Pages 1–35.in: Chelkowski, J. and Visconti, A. [Eds.] Alternaria: Biology, Plant Diseases, and Metabolites. Topics in Secondary Metabolism. Vol. 3, pp. 1–35. Elsevier, Amsterdam, the Netherlands.
Soteros, J.J. (1979) Detection ofAlternaria radicina andA. dauci from imported carrot seed in New Zealand.N.Z. J. Agric. Res. 22: 185–190.
Soteros, J.J. (1979) Pathogenicity and control ofAlternaria radicina andA. dauci in carrots.N.Z. J. Agric. Res. 22: 191–196.
Strandberg, J.O. (1983) Infection and colonization of inflorescences and mericarps of carrot byAlternaria dauci.Plant Dis. 67: 1351–1353.
Strandberg, J.O. (1987) Isolation, storage, and inoculum production methods forAlternaria dauci.Phytopathology 77: 1008–1012.
Strandberg, J.O. (1988) Detection ofAlternaria dauci on carrot seed.Plant Dis. 72: 531–534.
Tuite, J. (1969) Plant Pathological Methods. Burgess Publ. Co., Minneapolis, MN, USA.
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Strandberg, J.O. A selective medium for the detection ofAlternaria dauci andAlternaria radicina . Phytoparasitica 30, 269–284 (2002). https://doi.org/10.1007/BF03039995
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DOI: https://doi.org/10.1007/BF03039995