Seed transmission of Pyrenophora tritici-repentis, causal fungus of tan spot of wheat

• Published in: European journal of plant pathology 1995-01, Vol.101 (1), p.81-91
• Main Authors: Schilder, A.M.C. (Cornell Univ., Ithaca, NY (USA). Dept. of Plant Pathology), Bergstrom, G.C
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; DISEASE TRANSMISSION; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; ORGANISME TRANSMISSIBLE PAR SEMENCE; ORGANISMOS TRANSMITIDOS POR SEMILLA; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; PYRENOPHORA; Pyrenophora tritici-repentis; SEEDBORNE ORGANISMS; SOIL TEMPERATURE; TEMPERATURA DEL SUELO; TEMPERATURE DU SOL; TRANSMISION DE ENFERMEDADES; TRANSMISSION DES MALADIES; TRITICUM AESTIVUM
• ISSN: 0929-1873; 1573-8469
• DOI: 10.1007/BF01876096

Seed transmission of Pyrenophora tritici-repentis, a common foliar pathogen of wheat, was investigated in soft white winter wheat cv. Frankenmuth and found to be non-systemic; the emerging coleoptile was infected externally by hyphal growth from the infected pericarp. Hyphae from the infected coleoptile then infected the first and second seedling leaves as they emerged. Coleoptile symptoms ranged from tiny brown streaks or spots to large, brown necrotic areas accompanied by cracking and distortion of the coleoptile. Small brown spots sometimes occurred on the first and rarely on the second seedling leaves, often accompanied by leaf distortion. Pseudothecial initials of the fungus were present within or on the seed remnants. Seed transmission efficiency was as high as 92% in vitro and 60% in potting soil outdoors. Seed infection did not affect germination in vitro, but slightly reduced emergence in potting soil. Seedling weight and height were reduced significantly. In potting soil, seed infection also resulted in delayed plant growth and increased tan spot severity at later stages of plant development. Under controlled conditions, seed transmission efficiency and incidence of pseudothecia on seed were negatively correlated with seed germination temperature in the range of 9 to 21 degree C, whereas frequency of recovery of the fungus from symptomatic coleoptiles and leaves were positively correlated with seed germination temperature. These results suggest that infected seed may serve as a source of inoculum for tan spot epidemics and for dispersal of strains of the fungus to new areas.