Strawberry diseases & pests: a field identification and action guide
A practical reference for farm managers. Walk the rows, match what you see to the sections below, take the immediate action, then log a Pest / disease observationin your daily report with a photo.
60-second triage
- Isolate: flag the affected plants and avoid moving tools or trays to clean rows.
- Photograph leaves (top and underside), fruit, crown, and any insects you see.
- Compare against the sections below to narrow it down.
- Apply the immediate action listed for that issue.
- Log the observation in today's report with the photos attached.
Mold on strawberry plants
The two molds you'll meet most often in the field.
Gray mold (Botrytis cinerea)
- Look for: soft, brown rot on ripening fruit covered in a fuzzy gray coating, often where a berry touches another berry, a leaf, or wet soil.
- Triggers: prolonged leaf wetness, dense canopy, overhead irrigation, picking when foliage is wet.
- Immediate action: remove and bag all infected fruit and any mummified berries; do not compost on-site. Open up the canopy by removing old leaves. Switch irrigation to early-morning only so plants dry by midday.
Powdery mildew (Podosphaera aphanis)
- Look for: white powdery patches on the underside of leaves, leaf edges curling upward, dull purplish blotches on the upper surface, malformed fruit with persistent seeds on the surface.
- Triggers: warm days, cool nights, moderate humidity, poor airflow.
- Immediate action: prune older infected leaves into a bag, improve airflow between plants, and prepare a sulfur or potassium-bicarbonate spray for that evening when temperatures are below 27°C / 80°F.
Bugs on strawberry plants
Identify the insect first — the right response depends on the species.
Spider mites (Tetranychus urticae)
- Look for: stippled, bronze, or dusty-looking leaves; fine webbing on the underside; tiny moving dots under a 10x loupe.
- Immediate action: hose the underside of leaves with water to knock back populations, then plan a release of predatory mites (Phytoseiulus persimilis) within 48 hours. Avoid broad-spectrum insecticides — they wipe out the predators too.
Tarnished plant bug / Lygus (Lygus spp.)
- Look for: "cat-faced" deformed berries with seedy, hardened tips; small green or brown shield-shaped bugs in the flowers at dawn.
- Immediate action: sweep-net the rows in the early morning to confirm presence, mow flowering weeds along the perimeter (their preferred host), and target spot-treat heavily infested rows only.
Aphids
- Look for: sticky honeydew on leaves, ant trails, clusters of soft green or yellow insects on new growth.
- Immediate action: rinse heavy clusters off with water; introduce or protect ladybugs and lacewings already on the farm. Insecticidal soap as a last resort.
Slugs & snails
- Look for: irregular holes chewed into fruit (often the underside), silvery slime trails on plastic mulch in the morning.
- Immediate action: place iron-phosphate bait between rows that evening; raise berries off the soil with straw or netting.
Strawberry fungicide: when, and when not
Fungicide is a tool, not a routine. Use it as a follow-up to a confirmed diagnosis, not as a hopeful blanket spray.
- Gray mold: rotate active ingredients (e.g. cyprodinil + fludioxonil, fenhexamid, pyraclostrobin) across bloom and early fruit set. Never apply the same chemistry twice in a row — Botrytis develops resistance fast.
- Powdery mildew: sulfur, potassium bicarbonate, or a labeled DMI fungicide. Apply in the evening; avoid sulfur within two weeks of any oil spray and when temps exceed 27°C / 80°F.
- Leaf spot / leaf blight: captan or copper-based products labeled for strawberries.
- Always: read the label for pre-harvest interval (PHI), worker re-entry interval (REI), and maximum applications per season. Record the product, rate, block, and time in today's daily report so the application is on the audit trail.
This guide is general agronomic information for triage in the field. It is not a substitute for a local extension diagnosis or the product label, which always governs.
Common strawberry plant diseases at a glance
| Disease | Tell-tale sign | First action |
|---|---|---|
| Gray mold | Fuzzy gray rot on fruit | Remove fruit, open canopy |
| Powdery mildew | White powder under leaves | Prune, improve airflow, sulfur in evening |
| Anthracnose | Sunken dark lesions on fruit | Remove fruit, avoid overhead water, rotate fungicides |
| Leaf spot / blight | Purple-edged spots on leaves | Remove old foliage; captan if widespread |
| Verticillium wilt | Outer leaves collapse, inner leaves stunted | Flag plants, do not replant strawberries in that block |
| Crown / root rot | Wilting despite moist soil, brown crown core | Improve drainage; remove and destroy affected plants |
After the field walk
Every observation belongs in the daily report so the owner sees the trend, not just the incident. Open today's report and attach the photos you took during triage.
Log it in today's report