Reducing fertilization to enhance management of thrips on roses

Over fertilization of ornamental crops can contribute to higher pest control costs because herbivorous insects respond positively to high nutrient levels in the crop. Reduction of fertilization could be a useful tactic in an integrated pest management program for thrips, and thus reduce dependence on chemical or biological control, if altered fertilization regimes reduced thrips populations with little loss in crop yield and productivity. In greenhouse studies, we show that host plant quality can be manipulated to reduce Frankliniella occidentalis populations and enhance biological control of this pest on roses with a commercially available predatory mite, Amblyseius swirskii. In field studies, we examined the feasibility of halving the standard fertilization rate for commercial production of potted roses without compromising crop quality. We propose that current fertilization rates for greenhouse or field production of roses can be significantly reduced to enhance management of pests without compromising crop quality.