Garlic mustard, wild parsnip, and spotted knapweed can be managed by hand pulling of seedlings or small plants for what type of infestations?

Hand pulling of seedlings or small plants is most effective when dealing with light infestations of garlic mustard, wild parsnip, and spotted knapweed. In these situations, the plants have not yet established a large presence, making it feasible for a person to remove them completely without excessive effort or the need for more advanced management techniques. This method allows for the prevention of seed production and helps reduce the overall population of the invasive species.

In cases of moderate, heavy, or severe infestations, the density and root systems of the plants can be more complex, making hand pulling alone insufficient. At these higher levels of infestation, the plants are often well-established, and removing them by hand might not effectively control the population. Additionally, such infestations may require more systemic approaches, such as the use of herbicides or other integrated pest management strategies, to ensure effective control and prevent regrowth.