Effects of different organic mulches on the soil surface arthropod community and weeds in snapdragon

Abstract

Cultural control practices, including the use of cover crops and mulches, are convenient non-chemical methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for their effects on soil surface arthropods, weeds, and mortality of snapdragon plants in the autumn of both 2007 and 2008 near Citra, Florida, USA. In both seasons, five treatments were compared: cowpea mulch, sunn hemp mulch, sorghum-sudangrass mulch, pine bark nuggets, and an unmulched control. Mulches were applied around snapdragon plants in small plots, and treatments arranged in a randomized complete block design with five replications. Arthropod groups sampled using pitfall and board traps varied in their responses to treatments. The numbers of Formicidae, Cicadellidae, Orthoptera, and small-bodied plant-feeders (aphids, whiteflies, and thrips) were higher in control or cowpea plots than several of the other mulch treatment plots, possibly because weed levels were higher in control and cowpea plots. Collembola, Diptera, Araneae, and Coleoptera did not differ among treatments in either season. Board traps were effective for assessing Gryllidae and some beetles in 2007, when both groups were more abundant in the control and cowpea mulch plots than in the pine bark nugget plots, but in 2008 catches were not affected by treatment. Predatory insects were not consistently affected by mulches. Buckeye caterpillars feeding on the plants were not affected by the treatments and caused 28% mortality to snapdragon plants in 2007 and 27% mortality in 2008.