Effects of killed cover crop mulch on weeds, weed seeds, and herbivores

The feasibility of killed cover crop mulches as an alternative to methyl bromide fumigation was investigated in spring bell pepper and fall collard production by examining post-dispersal predation on weed seed, predation on beet armyworm larvae and pupae, percent weed cover, invertebrate activity, activity of red imported fire ant, and crop yield. In three experiments, 5047 weed seeds were removed from cover crop mulch plots compared to 1860 seeds from standard production plots, and within treatments, predation increased significantly with decreasing seed size. Predation of beet armyworm pupae was 33% greater in cover crop mulch compared to conventional production plots. Fire ants were the main predator of weed seed and pest insects. In the two bell pepper experiments, weed cover per square meter was 31.8% less in standard production than in cover crop mulch plots. The mean number of invertebrates (other than fire ants) captured in pitfall traps was 5.8 +/- 0.1 plot(-1) versus 3.8 +/- 0.8 plot(-1) for cover crop and conventional treatments, respectively. There were 5734 fire ants captured in mulched cover crop plots compared to 1278 in conventional production plots. There was no significant difference in crop yield among treatments. The results suggest fire ants were more abundant where there was mulched cover and were important predators of weed seed and pest insects in killed cover crop plots and that cover crop mulches in summer pepper and fall collard production are potentially viable alternatives to black plastic mulch and soil fumigation. (c) 2006 Elsevier B.V. All rights reserved.