Systemic Insecticides and Their Use in Ornamental Plant Systems

Systemic insecticides are compounds that may be applied to plants as a foliar spray or to the soil/ growing medium as a drench or granules. These materials are absorbed by roots or into other tissues and then translocated to plant parts. This may then protect plants from damage associated with phloem-feeding insects such as the Hemipterans including aphids, whiteflies, mealybugs, and soft scales. Factors influencing the activity of systemic insecticides are absorption and translocation, which in turn are affected by plant species, plant age, plant growth rate, environmental conditions, soil/growing medium, and physiological variations of plants. The general advantages of systemic insecticides to ornamental plant systems (greenhouse, nursery, and interiorscape) are that plants are continuously protected for extended periods of time without needing repeat applications; once inside the plant, residues are less susceptible to ultra-violet light degradation or wash-off due to irrigation when applied to soils/growing media; no unsightly residues on plant leaves or stems when applied to the soil/growing medium; plants may be less directly harmful to natural enemies, workers, and consumers; may reduce transmission of plant pathogens; and systemic insecticides may be effective in suppressing insect pests located in areas that are not accessible with spray applications. The disadvantages of using systemic insecticides in ornamental plant systems include potential for secondary pest outbreaks; unintentional direct and indirect effects on beneficial and non-target organisms; potential leaching from potted plants; increased costs of newer systemic insecticides; and drench or granule applications to the soil/growing medium can be labor intensive. Despite the disadvantages, the use of systemic insecticides is a viable option for long-term protection of ornamental plants associated with greenhouses, nurseries, and interiorscapes for pest management.