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Disease Detection and Losses

Potential Yield Reductions in Maize Associated with an Anthracnose/European Corn Borer Pest Complex in New York. N. P. Keller, Graduate research assistant, Department of Plant Pathology, Cornell University, Ithaca, NY 14853; G. C. Bergstrom(2), and R. I. Carruthers(3). (2)Assistant professor, Department of Plant Pathology, Cornell University, Ithaca, NY 14853; (3)Assistant professor, Department of Entomology, Cornell University, Ithaca, NY 14853. Phytopathology 76:586-589. Accepted for publication 6 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/Phyto-76-586.

In a 2-yr field study, the individual and combined effects of Colletotrichum graminicola and Ostrinia nubilalis (European corn borer [ECB]) on grain yield and stalk rot development in a maize hybrid susceptible to both organisms were determined. In 1983, a year favorable for development of anthracnose leaf blight and stalk rot, plants infested with ECB and/or inoculated with C. graminicola at the whorl stage of development showed average grain reductions of 13.5% (12 q/ha), 35.2% (31.2 q/ha), and 46.5% (41.2 q/ha) in association with ECB injury, anthracnose development, and both ECB injury and anthracnose, respectively. The same treatments at the silk stage resulted in grain reductions of 6.4% (5.4 q/ha), 16.5% (13.8 q/ha), and 12.2% (10.2 q/ha), respectively. Inoculation and infestation of plants in the dough stage resulted in no yield reductions. In 1984, a year less favorable for anthracnose development, grain yield was reduced (10.7%, 9.6 q/ha) in plants inoculated with C. graminicola at the whorl stage and infested with ECB at the kernel blister stage but was not reduced in plants inoculated and/or infested at later growth stages. Even minimal stalk damage by ECB significantly predisposed plants to anthracnose stalk rot development. Anthracnose stalk rot-induced grain reductions in New York consistently have been associated with early or midseason ECB infestations.