Planning reference

Cutworms vs Damping-Off

Separate cutworm soil-line clipping from damping-off stem collapse before adding collars, spraying, watering more, resetting trays, or re-sowing seedlings.

What each seedling failure signal means

Cutworms

Cutworms are soil-hiding caterpillars that feed mostly at night. They clip outdoor seedlings at or below the soil line, sometimes drag pieces below the surface, and curl into a C-shape when disturbed.

Damping-off

Damping-off is a seedling disease problem where seeds fail, roots rot, stems become water-soaked or pinched at the media line, and young seedlings collapse instead of recovering.

Clean cuts at the soil line

Cleanly severed stems, missing seedlings, and a curled larva in nearby soil point toward cutworms, especially in weedy or residue-heavy beds after transplanting or direct sowing.

Pinched, water-soaked stems and root rot

Dark, narrowed, mushy stems, root rot, whole tray sections failing, cool wet media, dirty containers, or garden soil in trays point toward damping-off instead of a chewing pest.

Outdoor beds vs seed-starting trays

Cutworm checks start in the bed soil, under residue, and around clipped plants. Damping-off checks start with tray sanitation, seed-starting mix, drainage, airflow, media temperature, and watering.

Seedling failure workflow

Read the stem before treating

Do not treat every missing, clipped, wilted, or collapsed seedling as the same problem; check whether the stem is cleanly cut, dragged underground, pinched, water-soaked, mushy, or rotted, inspect nearby soil for curled C-shaped larvae, inspect tray media, drainage, sanitation, temperature, and row-cover history, then choose collars, hand removal, tray reset, airflow, warmer media, or re-sowing.

Scout the newest outdoor damage at night

For direct-sown or transplanted beds, check around freshly clipped seedlings after dark and dig lightly in the top inch of soil near the stem. Remove larvae and protect remaining stems before re-sowing.

Reset dirty or collapsed trays cleanly

For trays with pinched stems or root rot, remove failed seedlings, avoid reusing suspect media, wash containers, use fresh seed-starting mix, and keep media evenly moist instead of saturated.

Do not spray the wrong target

Bt or hand removal can help exposed caterpillars when they are small, but damping-off needs sanitation, moisture, warmth, drainage, and airflow. Fungicides or insect controls do not rebuild collapsed stems.

Choose re-sowing timing by cause

Re-sow outdoor gaps after the cutworm source is removed or stems are collared. Re-sow tray cells after the media and container conditions are corrected so new seedlings do not collapse in the same setup.

Use these paths

• Slugs vs Cutworms Separate ragged slug chewing and slime trails from cutworm soil-line clipping before drying beds, adding collars, or re-sowing
• Cutworms vs Armyworms Separate cutworm soil-line clipping and C-shaped larvae from armyworm egg masses, group feeding, and skeletonized leaves
• Seedling Wilting vs Damping-Off Separate ordinary wilt from soil-line collapse before changing watering, light, media, or sanitation
• Fungus Gnats vs Damping-Off Separate tiny flies and larvae in moist media from damping-off stem collapse and tray sanitation problems
• Seed-Starting Mix vs Garden Soil Use clean tray media and avoid garden soil when damping-off points to contaminated or wet media
• Direct Sow Garden Planner 85 direct-sow-capable varieties where seedbed gaps, cut stems, and re-sowing timing matter
• Transplant Garden Planner 50 transplant-capable varieties where collars, tray sanitation, and early seedling recovery matter

Source basis

• UC IPM cutworms Cutworm larvae hiding in soil by day, night feeding, clipped plants, field scouting, weeds, plant residue, and early-season injury checks
• UC IPM snails and slugs Snail and slug slime trails, irregular holes, moist hiding places, night scouting, habitat reduction, barriers, traps, and baits
• UMD Extension cutworms Seedlings cut off near ground level, nighttime feeding, daytime soil hiding, collars, weed removal, and transplant protection
• UMN Extension cutworms Cutworm seedlings clipped at or below the soil line, C-shaped larvae, night feeding, weed control, collars, and scouting guidance
• UMN Extension preventing seedling damping off Damping-off symptoms, water-soaked pinched stems, root rot, tray sanitation, cool wet conditions, garden soil risk, and fungus gnat carrier note
• UMN Extension slugs Slug slime trails, ragged chewing, night feeding, moisture, shelter, handpicking, traps, and garden sanitation guidance
• UMN Extension starting seeds indoors Clean trays, fresh media, moisture, light, warmth, and seedling damping-off prevention context for indoor starts