In the context of sustainable horticulture, how can volunteer plants be seen as a challenge?

Volunteer plants can pose a challenge in sustainable horticulture primarily because they may introduce pests or attract them. This phenomenon occurs because these uninvited plants can serve as hosts for various pests and diseases that could otherwise be absent in a managed landscape. For example, a volunteer plant could be particularly appealing to certain insects, both beneficial and harmful, leading to an imbalance in the garden's ecosystem. Additionally, these plants may not have been selected for their pest resistance or compatibility with other cultivated plants, thereby increasing the risk of pest infestations.

While other options touch on various aspects of pest management, they don’t fully encapsulate the specific risks associated with volunteer plants. It's important to recognize that managing pest populations is a critical part of sustainable gardening, and volunteer plants can complicate that management by creating unexpected challenges that may not be addressed without careful monitoring and intervention.