Why might weeds still appear in a managed lawn like Mrs. Zimmerman's?

Weeds can often appear in managed lawns for several reasons, and the presence of seed dispersal by environmental factors is a significant one. Wind and birds are common vectors for the dispersal of weed seeds. When the seeds are carried by the wind or dropped by birds, they can easily land in a well-maintained lawn, where conditions may be favorable for germination and growth. This process can introduce new weed species into an area, even if the lawn has been managed properly in terms of mowing, fertilizing, and applying herbicides.

While resistance to herbicides and rapid growth can contribute to the persistence of weeds, the introduction of new seeds from external sources, like wind or birds, represents a direct cause for the appearance of weeds that may not have been present previously. Regular maintenance practices may minimize established weeds but do not fully prevent new seeds from establishing themselves in the lawn. Proper lawn management should include strategies to control not only existing weeds but also to prevent new infestations from external seed sources.