Enter Conditions
Use local observations and recent weather. Values are adjustable for “what-if” comparisons.
Example Data Table
These sample scenarios show how conditions affect the risk score.
| Scenario | Soil °C | Moisture | Weeds | Stage | Protection | Score | Risk |
|---|---|---|---|---|---|---|---|
| Cool, clean bed | 12 | Dry | Low | 3–4 leaves | Collars | 18 | Low |
| Typical spring | 18 | Normal | Medium | 1–2 leaves | None | 52 | High |
| Warm, weedy, wet | 22 | Wet | High | Emergence | Cover + collars | 71 | High |
Formula Used
The calculator uses a weighted score from 0 to 100. It adds points for conditions that favor cutworm activity and subtracts points for protective actions.
| Factor group | Max points | How it is scored |
|---|---|---|
| Soil temperature | 18 | Peak near 18°C, decreases with distance. |
| Soil moisture | 14 | Dry 4, normal 10, wet 14. |
| Rainfall (7 days) | 12 | Linear scale from 0–80 mm. |
| Weed/grass pressure | 18 | None 0 → High 18. |
| History + borders | 30 | More history and nearby weeds add risk. |
| Crop + stage | 36 | Susceptible crops and seedlings score higher. |
| Tillage + residue | 26 | No-till and heavy residue increase shelter. |
| Mitigation credits | -34 | Collars, covers, scouting, predators reduce score. |
Final score = clamp(Base points − Mitigation credits, 0, 100). Risk bands: Low < 25, Moderate 25–49, High 50–74, Severe ≥ 75.
How to Use This Calculator
- Measure soil temperature near seedlings (about 5 cm deep).
- Estimate moisture and weeds in the bed and borders.
- Enter crop type, growth stage, and prior cutworm pressure.
- Add any protection methods you already use.
- Press Calculate Risk to view score and actions.
- Download CSV or PDF to keep records for each bed.
How Risk Score Reflects Field Reality
This tool converts observations into a 0–100 risk score. Scores under 25 are Low, 25–49 Moderate, 50–74 High, and 75 or above Severe. Base points come from weather, habitat, and crop vulnerability, then credits subtract for protection steps. When conditions stack up, factor points can exceed 100, so the final score is clamped for comparisons.
Temperature And Moisture Signals
Cutworms feed most aggressively when soil is mild. The temperature factor peaks near 18°C and tapers as soils move colder or hotter. Night warmth also matters, adding up to 10 points as nights rise from about 5°C to 20°C. Rain is scaled across the last seven days, reaching the full 12 points near 80 mm. Wet soil moisture adds 14 points, while dry adds only 4.
Habitat Factors That Raise Pressure
Weed and grass cover is one of the strongest drivers, ranging from 0 points in clean beds to 18 points when weeds are high. Weedy borders add up to 12 points because moths often lay eggs nearby. No-till and heavy residue can add shelter, contributing up to 26 points combined from tillage and mulch levels.
Crop Vulnerability And Growth Stage
Seedlings are the main target, so emergence can add 18 points while established plants add only 3. Susceptible crops such as brassicas, tomatoes, peppers, and leafy greens score higher than less preferred crops. When a sensitive crop is paired with early growth stage, the calculator typically flags scouting urgency even if other factors are average.
Using Results For Action Planning
Mitigation credits reduce the score by rewarding practical controls: collars and row covers can subtract 10 points each, strong predator activity subtracts up to 6, and frequent scouting subtracts up to 8. Use the “Top drivers” list to prioritize fixes, then rerun scenarios to see how weed control or added protection changes risk. Scout at dusk, check around stems, and replace plants quickly. Save CSV or PDF outputs to compare beds and seasons weekly.
FAQs
When is the best time to scout for cutworm damage?
Check at dusk and early morning. Look for freshly cut stems, wilted seedlings, and larvae hiding under residue or just below the soil surface within 5–10 cm of the plant.
What should I do if the score is High or Severe?
Increase scouting to daily for at least a week, protect seedlings with collars or covers, and reduce weeds and residue near stems. Replace heavily damaged plants and track results with the export buttons.
Do plant collars replace other prevention steps?
Collars reduce cutting at the stem, but they work best alongside weed control, residue management, and regular scouting. Combining methods lowers risk faster than relying on a single action.
How can I estimate soil moisture without instruments?
Squeeze a small soil sample. Dry soil crumbles, normal soil forms a weak ball, and wet soil stays sticky or glossy. Recent rainfall and irrigation timing can also guide your choice.
Can I use this for raised beds or containers?
Yes. Use bed-level conditions: soil temperature in the root zone, recent watering as “rain,” and weed pressure around the bed edges. Containers often have fewer weeds but can still be affected.
Why does previous history influence the score?
Past infestations indicate local populations and suitable habitat. If cutworms were frequent, eggs or larvae are more likely to persist nearby, so early-season protection and tighter scouting are usually justified.