Wang, Q., Y. Li, Z. Handoo, and W. Klassen. 2007. Influence of cover crops on populations of soil nematodes. Nematropica 37:79-92. A pot experiment was carried out in south Florida to elucidate suppressive or antagonistic effects of several cover crops grown in rotation on soil nematode populations. The crops were two marigolds, Tagetes patula L. Dwarf Double French Mix (MDF), and Tagetes patula L. 'Lemon Drop' (MLD), Indian mustard (IM) [Brassica juncea (L.) Czern.], radish (RD) [Raphanus sativus L.], sunn hemp (SH) [Crotalaria juncea L., Tropic Sun], velvetbean (VB) [Mucuna deeringiana (Bort.) Merr.], a Meloidogyne-susceptible cowpea (CP) [Vigna unguiculata (L.) Walp, Purple Knuckle Hull], and okra (OK) [Abelmoschus esculentus (L.), Clemson Spineless 80]. Eight rotation schemes each with 3 rotations were carried out from June, 2002 to December, 2003. Those schemes were MDF-RD-MDF, MLD-CPMLD, IM-VB-IM, RD-MDF-RD, SH-OK-SH, VB-IM-VB, CP-MLD-CP, and OK-SH-OK. The results showed that marigolds, sunn hemp and velvetbean effectively suppressed root-knot nematodes, but okra, Indian mustard, radish and Purple Knuckle Hull cowpea promoted population growth of the root-knot nematode, Meloidogyne incognita. Furthermore, the antagonistic effect of the nematode suppressive crops carried over to reduce the infestation of plant-parasitic nematodes in the following crop. The results indicate that rotating marigold with other ornamental plants or rotating nematodesuppressive cover crops, such as sunn hemp, with field or cash crops may strongly suppress plant-parasitic nematode populations and benefit the following crop.
