PARENT SESSION
Poster Session # 22: Late-Breaking Newsworthy Posters
Friday, August 8 Presentation from 8:30 AM to 10:00 AM. SITCC Exhibit Hall B.
Killed cover crops as mulches for vegetable production: Effects on weed seeds, weeds, and pest insects.
Pullaro, Thomas*,1, 2, Marino, Paul1, Jackson, Michael3, Harrison, Howard3, Keinath, Anthony4, 1 College of Charleston, Charleston, South Carolina, USA2 NOAA, Charleston, South Carolina, USA3 USDA, ARS, U. S. Vegetable Laboratory, Charleston, South Carolina, USA4 Clemson University, Charleston, South Carolina, USA
ABSTRACT- The feasibility of killed cover crop mulches as an alternative to methyl bromide fumigation was investigated in spring bell pepper (Capsicum annuum L.) and fall collard (Brassica Oleracea var. viridis L.) production. Experiments were conducted in Charleston, SC during summer and fall-2000 and summer-2001. Specifically, production using killed cover crop mulches was compared to conventional production in terms of post-dispersal weed seed predation, pest insect predation, percent weed cover, invertebrate activity, red imported fire ant (Solenopsis invicta) activity, and crop yield. Vertebrate exclusion cages made from 1.3 cm2 (allows both fire ants and larger invertebrates entry) and 0.32 cm2 (allows only fire ants entry) wire mesh were used to quantify predation of weed seeds and pest insects by invertebrates. In three experiments, a total of 5047 weed seeds were removed from cover crop mulch plots compared to 1860 seeds from standard production plots, and predation increased significantly with decreasing seed size (p<0.0001). Predation of beet armyworm pupae was 33% greater in cover crop mulch compared to conventional production plots. Predation of weed seeds and pest insects did not differ significantly between small and large mesh cages. In the two bell pepper experiments, percent weed cover per m2 was 31.8% less in standard production compared 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. Our results suggest that fire ants are more abundant where there is mulched cover and because of this were important predators of weed seeds and pest insects in killed cover crop plots.
Key words: cover crop mulches, biological control, weeds, seed predation