Pests and Diseases
Aphids
Aphids are tiny, soft-bodied insects that cluster on new growth and the undersides of leaves. They suck sap from plants, causing leaves to curl, yellow or become distorted. As they feed, they excrete sticky honeydew that encourages sooty mould, and colonies can build quickly in warm weather.
Start with organic controls: blast colonies off with a firm jet of water, encourage beneficial insects like ladybirds and lacewings, and spray neem oil or insecticidal soap to disrupt feeding. Keep plants well watered and avoid excess nitrogen that promotes soft growth. If pressure remains high, selective chemical sprays can be used sparingly, taking care to protect pollinators and beneficials.
Leaf spot
Leaf spot describes several fungal or bacterial diseases that create dark, often round lesions on foliage—sometimes with yellow halos. Severe infections cause premature leaf drop and reduced vigour, especially during warm, wet spells or when leaves stay damp.
Reduce spread by removing infected leaves, watering at the base, and spacing plants for airflow. Mulch to limit soil splash and rotate crops. Organic preventatives include copper and sulfur sprays applied early. If disease escalates, registered fungicides offer a chemical backup.
Crown / root rot (Wet)
Crown and root rots are caused by water‑loving fungi that attack stems at the soil line and roots below. Plants yellow, wilt, and eventually collapse because their roots can no longer supply water and nutrients—most common in heavy, waterlogged soils.
Prevention is key: improve drainage, raise beds, and water deeply but less often. Avoid injuring stems at the soil line and rotate away from affected beds. Solarising soil in summer can knock back pathogens. Chemical drenches have limited benefit in home gardens and are best used preventatively rather than curatively.
Powdery mildew
Powdery mildew appears as a white, talc‑like coating on leaves and stems. It thrives in warm days, cool nights, and still air, and can weaken plants by reducing photosynthesis, leading to yellowing and early leaf drop.
Prune for airflow, avoid overhead watering, and remove badly affected foliage. Organic sprays such as milk solution, potassium bicarbonate, sulfur, or neem help suppress outbreaks. Chemical fungicides are effective when started early, but use sparingly to preserve beneficial organisms.
Slugs & snails
Slugs and snails chew irregular holes in foliage and fruit and can wipe out seedlings overnight, especially in damp, sheltered spots.
Remove hiding places, water in the morning, and use beer traps, boards, or shelters to concentrate and hand‑pick. Copper barriers can deter them. For baits, iron‑based pellets are the safest organic option; use metaldehyde baits cautiously due to risks to pets and wildlife.
Rust
Rust diseases produce raised orange‑brown pustules on leaves and stems. Spores disperse easily on wind and water, causing repeated reinfection and gradual weakening of plants.
Remove infected material and avoid wetting foliage. Grow resistant varieties where possible and rotate crops. Organic sulfur or copper sprays can protect new growth; systemic fungicides are a chemical fallback if rust persists.
Scale insects
Scale insects can affect plant health and yields in home gardens. Typical symptoms include slowed growth, discolouration, and reduced productivity, often triggered by weather, nutrition, or cultural conditions.
Start with cultural fixes: rotate crops, improve soil with compost, water consistently, and choose resistant varieties. Organic sprays or amendments can reduce severity; chemical options are a last resort and should be used carefully and in accordance with labels.
