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Physiology and Biochemistry

Inhibition of Conidial Production of Verticillium dahliae with Ammonium Sulfate. D. R. Duncan, Assistant biologist, Department of Agronomy, University of Illinois, Urbana 61801; E. B. Himelick, plant pathologist, Illinois Natural History Survey, Champaign 61820. Phytopathology 76:788-792. Accepted for publication 5 February 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-788.

Dry weight and conidial production were reduced and hyphal morphology was changed when Verticillium dahliae was grown on Czapek-Dox broth amended with ammonium ion compared with its growth on unamended Czapek-Dox broth. Dry weight was not reduced if the ammonium ion-modified medium was buffered or amended with asparagine, alanine, threonine, or glutamine. Conidial production, however, was reduced on all ammonium ion-modified media compared with that on the unamended Czapek-Dox broth. These ammonium ion-induced growth alterations also were obtained when the medium's solute potential was lowered from -0.45 to -3.0 MPa. Conidial production on sugar maple sap amended with ammonium ion was similar to that on buffered, ammonium ion-amended Czapek-Dox broth. The results are discussed in relation to the use of fertilizers as a means of controlling Verticillium wilt.