Corn yields were measured after application of nematicides in 16 experiments, mostly in medium-to-heavily textured soil, at 12 locations in Iowa during 1973-1976. The average maximum yield increase in plots treated with nematicides was 21% over yields in untreated plots. Yields were correlated negatively with nematode numbers or nematode biomass in nearly all comparisons. Correlations of nemato...

One to two hundred nematodes from each of seven Xiphinema americanum-group populations were measured to determine the range of stylet and body lengths for juveniles and adults. First-stage juveniles were identified by the position of the replacement odontostyle (i.e., the tip of the replacement odontostyle overlapped the base of the odontophore). Nematodes were identified as second stage if the...

Fourteen morphologically putative populations of X. krugi were clearly separated into four different profiles by RFLP analysis (Alu I and Hinf I), sequencing of the ITS-1 region, and subsequent Maximum Likelihood phylogenetic analyses. These four profiles were further supported by a principal component analysis of morphometric characters that yielded four taxonomic clusters matching those produ...

A simple method for atomic force microscopy (AFM) of nematode cuticle was developed to visualize the external topography of Helicotylenchus lobus, Meloidogyne javanica, M. incognita, and Xiphinema diversicaudatum. Endospores of two isolates of the nematode parasite, Pasteuria penetrans, adhering to M. incognita and X. diversicaudatum were also visualized and measured by this technique. Scanning...

Distribution of Xiphinema americanum and four Meloidogyne spp, was studied in a vineyard over a 13-mo. period. The X. arnericanum population was concd in the upper 60-cm of undisturbed soil in the vine row, whereas the Meloidogyne species were distributed both in and between rows and to greater depths, similar to the distribution of the root system. Samples for assessment of X. americanum densi...

Initial morphometric data and descriptions of males and the four juvenile stages of Xiphinema coxi coxi Tarjan, 1964 collected from soil about the roots of alfalfa (Medicago sativa L.) at Gainesville, Florida, and from a greenhouse microplot at Fayetteville, Arkansas, are given. Males were similar morphometrically and in shape to females and had 3-5 preanal supplements. The four juvenile stages...