Which of the following is NOT a cultural control method?

Cultural control methods are practices that aim to reduce pest populations and disease incidence by modifying the environment, cultural practices, and agricultural techniques. The primary goal of cultural controls is to create conditions that are less favorable for pests while promoting plant health.

Pruning is a cultural control method as it helps improve airflow and light penetration, which can reduce disease incidence and pest infestations. Planting resistant varieties involves selecting plant strains that are less susceptible to pests and diseases, thus constituting another method of cultural control. Mechanical weeding also falls within cultural practices, as it reduces competition for resources and eliminates habitats for pests.

Applying systemic insecticides, however, does not fit into cultural control methods. Systemic insecticides are chemical treatments intended to directly control pest populations. They work by being absorbed into the plant and affecting pests that feed on it. This option represents a direct interference with the pest rather than modifying cultural practices to manage pest populations, making it distinctly different from the cultural controls described above.