Starting clean is an essential part of IPM. Despite strict pest control programs at the propagators’ facilities, it is relatively common to find low numbers of pests in shipments of floriculture propagative plant material (cuttings) to finishing greenhouses. These pests may be resistant to pesticides due to previous exposure at the propagator, limiting a grower’s control options. Even when biological control agents are applied right at the start of the crop, they may have a difficult time “catching up” as pest populations have a “head start”.

Dipping is a technique where unrooted cuttings are immersed in a suspension before they are stuck in growing media. We tested biopesticides (entomopathogenic fungi) and/or reduced risk materials such as insecticidal soap or mineral oil as a dip against Bemisia whiteflies, western flower thrips and two spotted spider mites on poinsettia, chrysanthemum and various bedding plants in research trials and commercial greenhouses. We also evaluated the risk of disease (Pectobacterium) transfer through the dipping process in poinsettia.

We demonstrated that cutting dips are an effective, economic and safe method to reduce pest infestation levels at the beginning of the production cycle and that biocontrol strategies are more effective thereafter. Furthermore, use of cutting dips in combination with biocontrol mitigates the risk of resistance, so that pesticides can be used as a clean-up spray at the end of production, if needed.