What is a plant pest?

Invasives, undesirables and weeds are plants that are pests.

Specifically, a pest can be defined as someone or something which causes aggravation and anxiety instead of admiration and appreciation. A plant that is invasive does not know how to share resources and outcompetes what the cultivator, farmer or gardener seeks to have growing in the area. An undesirable is a plant that is not where its caregiver intends for it to be. A weed may either be in the wrong place at the wrong time or have value which is forgotten, unknown or unwanted.

All of the three above-mentioned cases will result in varying degrees of agonized reactions from the person concerned.