What symptom indicates feeding by billbugs?

Feeding by billbugs is characterized by significant damage to the plant's structural integrity, which is most clearly indicated when stems break easily upon being pulled. Billbugs are a type of weevil that primarily feed on the stem and crown of turf grasses, disrupting their growth and reducing their resilience. This feeding behavior can lead to weakened stems, making them brittle.

The other symptoms mentioned, such as yellowing leaves or browning at the tips, are typically associated with other issues, such as nutrient deficiencies or diseases. While root decay can be a concern in turf management, it is not directly linked to billbug feeding, as billbugs primarily target the above-ground parts of the grass rather than the roots. Thus, the easy breaking of stems under tugging pressure is a clear and specific indicator of damage caused by billbugs.