Diagnosing Lawn Damage: Grubs vs. Fungus in Chicago

Interpreting Symptoms

A 3-inch hole with surrounding yellowing grass that pulls up easily suggests two possibilities:

Grub Damage

• Turf rolls up like carpet (roots severed)
• Drought stress symptoms despite adequate water
• Confirm by digging 1 ft deep with post-hole digger; 4+ grubs/sq ft = treatment threshold

Fungal Disease

• Waterlogged appearance, sloughing at crown (above ground)
• Brown-black sheath discoloration, possible odor
• Different from drought stress symptoms

Next Steps

1. Dig test holes to confirm grub presence
2. If grubs confirmed and threshold met, apply labeled control
3. If no grubs, consider fungal diagnosis—sample to Extension office
4. Mysterious hole itself may be primary cause—fill and sod if isolated

Chemical application without confirmed target and threshold is irresponsible and potentially illegal.