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Certain Factors Influencing the Development of Northern Corn Leaf Blight Following Seedling Inoculation 1
Author(s) -
Andrew R. H.,
Rowe P. R.,
Oelke E. A.
Publication year - 1964
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1964.0011183x000400010002x
Subject(s) - seedling , blight , rowe , biology , library science , crop , horticulture , citation , agronomy , management , computer science , economics
SEVERITY of northern corn leaf blight caused by Helmintbosporium turcicum Pass, is characterized by extensive seasonal variation. Relatively cool weather accompanied by heavy dews and high humidity generally is considered as favoring the disease, while warm, dry weather checks it (16). Differences in severity are due to variation in environment (3), in pathogenicity of the causal organism (7, 11, 12, 14), in host resistance (2; 4, 5, 6) and to interactions of these factors. Because of variation in the severity from natural infection, artificial • epiphytotics are frequently established for selection in breeding programs. In such programs, F2 and backcross populations of corn (Zea mays L.) have shown continuous gradation from high resistance to high susceptibility without segregation into distinct classes, indicating that numerous genes are involved (16). After inoculation, resistant strains show fewer but essentially similar lesions as compared with those on susceptible plants. Resistance usually is not expressed fully until plants are 6 to 8 weeks old (15). Recently an apparently different type of resistance to H. turcicum has been reported which shows smaller lesions with chlorotic margins and inhibited sporulation (9).