Diagnosis
Diagnose: Squash Vine Borer on Zucchini
Use these observations to decide what to check next.
A cream-colored squash vine borer larva is feeding inside the crown or lower stem
Inspect a wilted plant early in the day.
Look for a hole or split near the soil line with moist coarse frass, then press the crown to find the length of firm tissue. Strong-sun wilt alone is not enough because drought, bacterial wilt, crown rot, and squash bugs can weaken zucchini without leaving a frass-filled tunnel.