Squash as a trap crop to protect tomato from whitefly-vectored tomato yellow leaf curl

Abstract

The silverleaf whitefly, Bemisia argentifolii Bellows & Perring [also known as biotype B of the sweetpotato whitefly, B. tabaci (Gennadius)], is a key pest of tomato in southern Florida. Most damage by the whitefly is inflicted indirectly through the transmission of plant viruses, the most damaging of which is Tomato yellow leaf curl virus (TYLCV). Trap crops may be one means of reducing whitefly populations and TYLCV incidence in tomato. Because squash is more attractive to whitefly adults than tomato, it was evaluated as a trap crop in three field experiments conducted during the spring and fall of 2000 and the spring of 2001. Four, 15.25 m long rows of tomato were surrounded by 1.5 m of either squash or tomato and were transplanted about 3 weeks after the squash was seeded. The numbers of whitefly adults and nymphs and the incidence of plants with symptoms of tomato yellow leaf curl (TYLC) were determined weekly. The squash was harvested weekly to promote flowering, and fungicides were applied weekly for preventive control of fungal pathogens. In all experiments, a greater cumulative proportion of plants with symptoms of TYLC were observed on tomato plants surrounded by tomato, compared to tomato plants surrounded by squash. In general greater cumulative numbers of whitefly adults and nymphs were observed on tomato plants surrounded by tomato than on tomato plants surrounded by squash. Therefore, growing squash as a trap crop could be a useful cultural manipulation in managing the silverleaf whitefly and TYLC on tomato, although the management tactic may be more applicable to small-scale farm operations.