In a field experiment on Myakka fine sand, high populations of Belonolaimus longicaudatus and Hoplolaimus galeatus and a moderate population of Paratrichodorus christiei developed on a summer cover crop of sorghum-sudangrass hybrid (Sorghum bicolor .times. S. sudanense). Populations of B. longicaudatus increased moderately on cowpea (Tigna unguiculta) but populations of H. galeatus and P. christiei did not increase on this crop. Populations of B. longicaudatus and H. galeatus did not increase on hairy indigo (Indigofera hirsuta) and joint vetch (Aeschynomene americana) but a moderate increase of P. christiei occurred on both. No increase in nematode numbers was found in fallow plots, but a moderate population of H. galeatus persisted during 3 mo. of fallowing. In-row applications of 2.24 kg ai [active ingredient]/ha of fenamiphos significantly increased the yield of the 1st crop (cabbage) following sorghum-sundangrass but not following the other cover crops or fallowing. Yields of the 2nd crop in the rotation (field corn) were significantly higher where fenamiphos was applied to both crops in the rotation than where none was applied following the cover crops of sorghym-sudangrass and cowpea but not for hairy indigo, joint vetch, or fallowing. A single application of fenamiphos applied to either cabbage or corn increased corn yields significantly only after sorghum-sudangrass.
