Inter-row Soil Cover to Reduce Incidence of Aphid-borne Viruses in Pumpkin

Abstract

ABSTRACT Inter-row soil cover used in conjunction with vegetable crop production has the potential to reduce aphid-borne plant virus incidence while also reducing the need for pesticide applications and preserving inter-row soil structure. In this study, inter-row soil covers were compared with a conventional, bare soil treatment for their ability to reduce aphid-borne virus incidence and associated yield loss in pumpkin (Cucurbita pepo L. var. pepo). In 2006, inter-row soil cover crops included Sericea lespedeza [Lespedeza cuneata (Dumont de Courset)] G. Don], and sunn hemp (Crotalaria juncea L.). Sericea lespedeza was used in the 2007 trial, but naturally occurring weed species were used instead of sunn hemp. Watermelon mosaic virus (WMV) was detected in the 2006 trial and Papaya ringspot virus (PRSV) and WMV were detected in the 2007 trial. In 2006, no differences were observed for WMV incidence among treatments, although significantly more aphids were identified on pumpkin plants in the Sericea lespedeza treatment. Enzyme-linked immunosorbent assay absorbance values for WMV accumulation in pumpkin plants for whole treatment, and for samples shown to be infected, were significantly lower in the Sericea lespedeza treatment, indicating less virus accumulation in these samples. No differences were observed among treatments for marketable pumpkin fruit number or yield. In the 2007 trial, WMV incidence was significantly less in pumpkin plants in the weed treatment compared with Sericea lespedeza early in the season, but incidence did not differ among treatments later in the season. PRSV incidence did not differ among treatments early in the season but was significantly lower in pumpkin plants in the Sericea lespedeza treatment than the bare soil treatment later in the season. Significantly more aphids occurred on pumpkin plants in the weed treatment than in the Sericea lespedeza and bare soil treatments. Significantly more aphids occurred on pumpkin plants in the Sericea lespedeza treatment than the bare soil treatment. Marketable pumpkin fruit numbers and yield were significantly greater for the Sericea lespedeza treatment than the bare soil and weed treatments. These data indicate that pumpkin plants grown with an inter-row soil cover may have less aphid-borne virus despite greater numbers of aphids.