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.
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.
Thrips
Thrips are slender insects that rasp and suck plant tissues, leaving silvery streaks and distorted growth on leaves and flowers. They can also transmit plant viruses.
Use blue or yellow sticky traps to monitor and reduce numbers, weed around beds, and encourage beneficials like minute pirate bugs. Neem oil and insecticidal soap offer organic suppression. If needed, use registered insecticides and rotate modes of action to avoid resistance.
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.
Leaf miners
Leaf miners 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.
Root-knot nematodes
Root-knot nematodes 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.
