VIEW ARTICLE

Effects of Nitrogen Compounds on Resistance of Gossypium arboreum Seedlings to Colletotrichum gossypii. Katharina Bollenbacher, Former Research Plant Pathologist, Plant Science Research Division, ARS, USDA, Arkansas 72701; N. D. Fulton, Professor of Plant Pathology, Arkansas Agricultural Experiment Station, Fayetteville, Arkansas 72701. Phytopathology 61:1394-1395. Accepted for publication 6 July 1971. DOI: 10.1094/Phyto-61-1394.

Gossypium arboreum ‘Nanking’ seedlings, which are resistant to Colletotrichum gossypii, were grown in a medium supplemented singly with 23 amino acids, KNO₃, NH₄H₂PO₄, (NH₄)₂SO₄, and NH₄NO₃. Plants were inoculated by placing a spore suspension of C. gossypii on the hypocotyls. Asparagine-amended medium induced complete susceptibility, and was not toxic to noninoculated plants. Other amino acids either induced less disease or were phytotoxic. Except for those which were phytotoxic, inorganic amendments did not affect resistance. Susceptibility was induced by growing the seedlings in asparagine-amended medium that had no contact with the inoculum. Evidence indicates that the supplements predispose the seedlings rather than increase virulence of the fungus.