Bean

Erysiphe spp.

A fungal disease producing a white powdery coating on leaf surfaces. Thrives in warm dry conditions with high humidity, and is particularly common in late summer. Rarely kills plants but significantly reduces vigour and harvest quality.

Uromyces appendiculatus

A common fungal disease of beans producing distinctive orange-brown pustules on leaves and pods. Most problematic later in the season and in humid conditions. Can reduce yield and plant vigour if established early.

Bean common mosaic virus (BCMV)

A virus spread primarily by aphids that causes mottled, distorted foliage and stunted growth. There is no cure once a plant is infected. Management focuses on removing infected plants and controlling aphid vectors to prevent spread.

Cucumber mosaic virus (CMV)

One of the most widespread plant viruses, spread primarily by aphids. Affects a broad range of crops including cucurbits, legumes, and herbs. There is no cure once a plant is infected; management focuses on controlling aphid vectors and removing infected material.

Plants are drooping or losing vigour. Most commonly caused by water stress but can also indicate root damage, vascular disease, or heat scorch. Identifying the cause quickly is important as some causes are serious.

Seeds are emerging unevenly or not at all. Usually caused by soil temperature being too low, seeds sown too deep, poor seed-to-soil contact, or old seed stock.

Pythium spp. / Phytophthora spp.

Young seedlings collapse at or just below soil level, caused by fungal pathogens that thrive in overwatered, poorly ventilated growing conditions. Can spread rapidly through a seed tray.

Leaves are turning yellow, which can indicate a range of problems including nutrient deficiency, overwatering, disease, or natural senescence. Identifying whether the pattern is upper or lower leaves, whole leaves or between veins, is key to diagnosis.

Plants are significantly smaller or slower to develop than expected. May be caused by poor soil, nutrient deficiency, root restriction, compaction, pest damage to roots, or disease.

Roots are decaying, usually caused by excess moisture, poor drainage, or soil-borne pathogens. Affected plants cannot take up water or nutrients effectively and typically decline rapidly.

Botrytis cinerea

Grey mould is an extremely common fungal disease that thrives in cool, damp, still conditions. It can affect almost any soft plant tissue - flowers, developing fruit, leaves, and stems. On strawberry it is one of the most significant causes of fruit loss.

Small sap-sucking insects that colonise soft new growth, leaf undersides, and growing tips. Most species reproduce rapidly and colonies can establish quickly in spring and early summer. Also vectors of several plant viruses.

Tetranychus urticae

Tiny mites (barely visible to the naked eye) that feed on the underside of leaves, causing pale stippling and fine webbing. Thrive in hot, dry conditions and reproduce extremely rapidly - populations can explode in a polytunnel or glasshouse during a heat wave.

Frankliniella occidentalis

Minute slender insects that rasp the surface of leaves and flowers, leaving characteristic silvery streaking. Can also spread tomato spotted wilt virus in some situations. More common in warm, dry conditions.

Soft-bodied molluscs that feed on plant material at soil level, most active at night and in wet conditions. A persistent pressure throughout the growing season, especially damaging to seedlings and young transplants.

Shell-bearing molluscs that feed on foliage and young plants, leaving similar damage to slugs. They are more active in mild, damp conditions and tend to shelter in visible daytime hiding spots such as walls, pots, and debris.

Aphis fabae

The black bean aphid is one of the most common and visible bean pests. Dense black colonies establish on growing tips and shoot undersides from late spring, weakening new growth and transmitting viruses. Particularly troublesome on broad beans.

Sitona spp.

Adult weevils that notch distinctive U-shaped bites from the leaf margins of bean plants. Rarely causes serious harm to established plants, but heavy damage to seedlings can be more significant. The larvae feed on root nodules.

Liriomyza spp.

Larvae of small flies that tunnel between the upper and lower surfaces of leaves, leaving characteristic winding pale trails or blotch mines. Damage is mostly cosmetic on established plants.

General chewing damage from an unidentified pest, leaving holes or missing leaf sections. May be caused by caterpillars, beetles, or other insects. Inspect at dusk to identify the culprit.

General sap-feeding pest activity causing weakened or distorted growth. May be caused by aphids, whitefly, scale insects, or other sucking insects. Inspect leaf undersides and growing tips to identify the pest.