Integrated impact of soil solarization and organic mulching on weeds, insects, nematodes, and plant performance.

Soil solarization is a hydrothermal method to increase soil temperature for managing soilborne plant pests that include insects, weeds, nematodes, and fungi, while mulching is an effective way to control weeds along with providing shelter for predatory insects. The integrated impact of soil solarization and mulching on weeds, nematodes, insect pests, and plant performance was evaluated in field-grown ‘Potomac Pink’ snapdragon (Antirrhinum majus L.) in Fall 2008 at the University of Florida Plant Science Research and Education Unit, Citra. Four treatments were compared: solarization (S), mulch (M), integration of mulch and solarization (MS), and an untreated control (C). Treatments were arranged in a randomized complete-block design with five replications. For the mulch treatment, a preplant mulch of sunn hemp (Crotalaria juncea L.) hay was applied over the bed surface. In the solarization treatment, beds were covered with Polydak® plastic film for 6 weeks. After 6 weeks, the plastic was removed, and all beds were planted with snapdragons. For MS treatment, plastic was applied as preplant, and sunn hemp mulch as postplant application. Data were collected on the mortality of snapdragon plants, weed ratings, nematode counts in soil, plant parameters (plant weight and number of blooms), and visual count of insects, especially buckeye caterpillar (Junonia coenia Hubner, Lepidoptera: Nymphalidae) and saltmarsh caterpillar [Estigmene acrea (Drury), Lepidoptera: Arctiidae]. Solarization or mulching alone reduced weed numbers but integration of solarization and mulching provided the most effective control of weeds. Population levels of large buckeye caterpillars were highest in the MS treatment. Plant mortality and plant parameters did not differ among the treatments. Extensive plant damage and mortality due to caterpillars were observed in all plots.