Strawberry

Potassium

Visible symptom

Scorched, purplish-brown margins on older leaves and small, soft, poorly coloured fruit with a shorter shelf life — potash fed at flowering is what actually builds fruit size, colour and firmness in strawberry.

Boron

Visible symptom

Poor fruit set and small, hard, misshapen ("cat-faced") berries with uneven seed distribution — boron is essential for pollen viability and fruit development, so a shortage shows up directly in the harvested fruit rather than just the leaves.

Nitrogen

Visible symptom

Pale, small, slow-growing plants on genuinely poor soil — but the more common mistake with strawberry is over-applying nitrogen, which produces lush, soft foliage that grey mould infects far more readily.

Grey mould (Botrytis)

Symptoms

A soft, watery rot on flowers, green fruit and especially ripening berries, quickly coated in a fuzzy grey-brown mould; infected berries collapse within a day or two of the first spot appearing, and the disease spreads fast through a wet, dense canopy at picking time.

Cause

The fungus Botrytis cinerea, spread by air-borne spores and favoured by cool, humid, wet or cloudy weather, especially during flowering and fruit ripening. It is considered the single most damaging disease of strawberry worldwide, capable of yield losses well over half the crop in an unmanaged, wet season.

Treatment

Remove and destroy infected flowers and fruit as soon as seen — do not leave rotted berries in the bed. Apply a recommended protective fungicide (rotated to avoid resistance) at flowering and again as fruit ripens if humid weather is forecast.

Prevention

Keep the canopy open with correct spacing, avoid overhead irrigation entirely, remove old leaves and spent flowers regularly, pick ripe fruit promptly rather than leaving it on the plant, and rely on the black plastic mulch to keep fruit off wet soil.

Red stele root rot

Symptoms

Stunted, wilted plants with a dull blue-green or reddish tinge to the foliage and poor fruit set; splitting an affected taproot lengthwise shows a telltale reddish-purple core (the "stele") inside an otherwise normal-looking root, which is the confirming sign.

Cause

The soil-borne water-mould Phytophthora fragariae, a genuinely distinct pathogen from the Phytophthora species behind late blight, pepper foot rot or avocado root rot. It thrives specifically in cold, waterlogged, poorly drained soil and spreads in surface water and on infected planting material.

Treatment

There is no cure once red stele is established in a plant or a plot — remove and destroy affected plants and avoid replanting strawberry in the same bed for several years.

Prevention

Plant only on well-drained raised beds, never in a low-lying or heavy-clay spot that holds water; buy certified, disease-free runners or tissue-culture plantlets only; and avoid moving soil or irrigation water between an affected planting and a healthy one.

Anthracnose

Symptoms

Small, sunken, dark brown to black spots on ripening fruit that enlarge and can rot the whole berry; on the crown, a reddish-brown internal rot that wilts and kills the plant outright, especially in warm, humid weather.

Cause

Colletotrichum species (including C. acutatum, C. fragariae and C. gloeosporioides), spread by rain-splash and irrigation water from infected runners and debris, favoured by warm, wet, humid conditions — genuinely worse on some black-plastic-mulched plantings where splash from the mulch surface carries spores onto low fruit.

Treatment

Remove and destroy infected fruit and crowns promptly; apply a recommended protective fungicide at the first sign, especially through a warm, wet spell during fruiting.

Prevention

Source certified, disease-free runners or tissue-culture plantlets, avoid overhead irrigation, keep the canopy open for airflow, and rotate out of strawberry for a few years where the disease has a history.

Powdery mildew

Symptoms

A white, powdery coating on the underside of leaves that curl upward at the edges, followed by a similar coating on flowers and fruit that gives berries a dull, poor finish and off-taste.

Cause

Podosphaera aphanis (grouped with the wider Erysiphales fungi that cause powdery mildew across many crops), favoured by warm, dry days with high humidity at night — a different weather pattern from grey mould's cool-wet preference, so both diseases can appear in the same season at different stages.

Treatment

Apply a recommended sulphur-based or systemic fungicide at the first sign of the white coating, before it reaches the fruit; follow the label and pre-harvest interval closely on a crop picked every 2–3 days.

Prevention

Choose a well-ventilated spacing, avoid excess nitrogen that produces dense, susceptible foliage, and scout the underside of leaves regularly rather than waiting for the coating to become obvious from above.

Two-spotted spider mite

Identification

Tiny, barely visible mites on the underside of leaves, often with fine webbing across the leaf surface in a heavy infestation; affected leaves show a fine yellow-white stippling that spreads and eventually bronzes the whole leaf.

Damage

Feeding drains the leaf of chlorophyll and, in a hot, dry spell, can build up fast enough to weaken the whole plant and cut fruit size and yield noticeably. It is one of the most common strawberry pests in India, especially in warm, dry weather.

Organic control

Regularly hose down or spray the leaf undersides with water to disrupt colonies, release predatory mites where available, and avoid the dusty, water-stressed conditions that favour a mite build-up.

Chemical control

A recommended miticide only where infestation is heavy and spreading fast, rotated between different modes of action since spider mites build resistance quickly; observe the pre-harvest interval strictly given how often the crop is picked.

Aphids

Identification

Small, soft-bodied insects clustering on new leaves and flower stalks, often with sticky honeydew and sooty mould developing beneath them.

Damage

Direct feeding is usually minor, but aphids can transmit plant viruses between strawberry plantings, so a build-up is a warning sign for the health of next year's planting material as much as a pest problem in its own right.

Organic control

Yellow sticky traps, a strong water spray to dislodge colonies, and conserving ladybird beetles and other natural predators.

Chemical control

A recommended insecticide where aphid numbers build fast, particularly in mother-plant nursery blocks kept for runner production, observing the short pre-harvest interval needed on a crop picked every few days.

Cutworms and white grubs

Identification

Fat, greyish-brown caterpillars (cutworms) that hide in the soil by day and feed at night, or creamy-white C-shaped grubs (white grubs) found in the soil around the roots and crown.

Damage

Cutworms sever young transplants at the soil line soon after planting, sometimes wiping out whole patches of newly set runners; white grubs feed on roots and the crown underground, weakening or killing established plants.

Organic control

Hand-pick cutworms found at the base of damaged plants at dusk or after dark, deep-plough the bed before planting to expose grubs to birds and predators, and keep the bed free of undecomposed organic matter that attracts egg-laying adults.

Chemical control

A recommended soil insecticide worked into the bed at preparation where cutworm or white grub pressure has a history on the plot.

Birds

Identification

Peck marks and partly eaten berries on the ripest, most exposed fruit in the bed, usually worst near field edges and in the days just before a planned picking.

Damage

Birds are drawn to ripening strawberries as readily as to any other soft fruit and can strip a surprising amount of the ripest, most marketable fruit if a planting is left unprotected, especially in smaller or isolated plots.

Organic control

Netting stretched over the bed during the ripening and picking window is the most reliable protection; reflective tape, scarecrows and noise-makers give partial, short-lived relief at best.

Chemical control

Not applicable — bird damage is managed by physical exclusion, not chemical control.