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Nonrandom Spatial Distribution of Aphid-Vectored Maize Dwarf Mosaic. Gene E. Scott, Supervisory Research Agronomist, Crops Science Research Laboratory, Agricultural Research Service, U.S. Department of Agriculture, and Professor of Agronomy, Mississippi State University, Mississippi State 39762. Plant Dis. 69:893-895. Accepted for publication 4 March 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-893.

Ordinary runs analysis was used to determine if plants of corn (Zea mays) with maize dwarf mosaic (MDM) were randomly distributed within the row. Hybrid B had at least twice as many MDM-diseased plants as hybrid A. In 1982 and 1983, the distribution of diseased plants was nonrandom, and the extent of nonrandomness was greater for hybrid B than for hybrid A. The distribution of disease in rows of 50, 100, 200, and 400 plants was compared with simulated data generated with given probabilities for a diseased plant to follow a healthy plant (pHD) and for a diseased plant to follow a diseased plant (pDD). The observed frequency of pDD was 0.15 greater than pHD for hybrid B in both years but somewhat less for hybrid A. Because aphids are the distributors of maize dwarf mosaic virus in the field, the likelihood of aphids carrying the virus to adjacent plants is 15% greater than to nonadjacent plants.

Keyword(s): disease spread, epidemiology.