Significantly higher numbers of stalk borer (SB) Papaipema nebris (Guenée) larvae infested no-till corn seedlings were found adjacent to (ie. ca 4 m) field margins, compared to numbers found 30 meters from field margins. Plant species abundant in the areas surrounding SB infested no-till corn fields in southwestern Virginia included tall fescue, Fescuta arundinacea Schreb., and orchardgrass, Dactylus glomerata L.
Contour and transect maps of infested fields from 1983 to 1985 suggested SB distribution to be clumped. This distribution was confirmed by high variance to mean ratios of 7.3, 5.8, 12.4, and 9.4 for 1983, 1984, 1985a and 1985b fields, respectively. Green's coefficient of dispersion and Morisita's coefficient of dispersion showed clumping of the SB independent of the mean, variance, and sample size. This is the first documentation that the SB infests fields predominantly on field borders, and the first quantification of the distribution of the SB in no-till corn.
Author notes
2 Present address: Texas Agricultural Experiment Station, Pearsall Substation, P.O. Box 524, Devine, TX, 78016.
