We evaluated the use of companion planting and masking odors to protect roses against the Japanese beetle, Popillia japonica Newman. In a field experiment, three companion species including rue (Ruta graveolens L.), zonal geranium (Pelargonium x hortorum Bailey), and garlic chives (Allium scheonparum L.) were interplanted with two flowering roses. The number of beetles on these roses was compared to a rose only control plot on six days during July 2001. Another set of experiments tested the masking odor hypothesis by hanging mesh bags of aromatic herbs or reputedly repellent plants around potted roses. Plants surrounded by these odor treatments were exposed in the field for 3 d and the number of beetles on the roses was counted daily. In both sets of experiments, no treatment significantly reduced the number of beetles relative to the control roses. Geraniums interplanted with roses had significantly more beetles than the roses in control plots. Similarly, in the second experiment, roses bordered by fennel seeds (Foeniculm vulgare Miller), cedar shavings (Juniperus sp.), crushed red pepper (Capsicum frutescens L.), and hedge-apples (fruit of Maclura pomifera (Raif)Schneid.) had significantly more beetles than the control roses on at least one sample. We suggest the use of companion planting and masking odors is not a likely alternative management strategy for Japanese beetles and may, under certain instances, increase beetle populations on plants to be protected.
Species 1: Coleoptera Scarabaeidae Popillia japonica (Japanese beetle)
Keywords: pest management, interplanting
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