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

Cultural control practices, including the use of cover crops and mulches, are environmentally safe methods for managing some insect pests and weeds. Several different types of organic mulches were evaluated for effects on soil surface arthropods, weeds, and plant mortality. Field experiments were conducted in fall 2007 and 2008 near Citra, FL. In both seasons, five treatments were compared: cowpea (Vigna unguiculata (L.) Walp.) mulch, sunn hemp (Crotalaria juncea L.) mulch, sorghum-sudangrass (Sorghum bicolor Moench X S. sudanense [Piper] Stapf) mulch, pine bark nuggets, and unmulched control. Mulches were applied around snapdragon (Antirrhinum majus L.) plants in small plots, and treatments arranged in a randomized complete block design with five replications. Data collected included arthropod counts using pitfall traps and board traps, weed ratings, direct counts of buckeye (Junonia coenia Hübner) (Lepidoptera: Nymphalidae) caterpillars, and snapdragon plant mortality. Arthropod groups sampled using pitfall and board traps varied in their responses to treatments. Numbers of Formicidae, Cicadellidae, Orthoptera, and small plant feeders (aphids, whiteflies, and thrips) were higher in control and cowpea plots, possibly because weed ratings were higher in control and cowpea plots. Buckeye caterpillars were not affected by the treatments and caused high mortality of snapdragon plants in all plots.