Carrot

Alternaria dauci

A fungal disease that causes dark lesions on carrot foliage, weakening plants and reducing root development. More common in warm, wet summers and where crops are sown densely.

Fungal decay of carrot roots caused by waterlogging or soil pathogens, particularly in heavy, poorly drained soils. Affected roots may be soft, discoloured, or malformed.

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.

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.

Psila rosae

A root-feeding pest whose larvae tunnel into carrot roots, making them poor quality or inedible. It is most active from late spring into autumn.

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.

Agriotes spp.

Slender, yellowish-brown soil-dwelling larvae of click beetles that tunnel into roots and tubers. Most problematic in ground recently converted from grass or in plots with a long history of soil. Damage is found at harvest rather than visible during the growing season.

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.

Damage to roots, tubers, or underground plant parts from soil-dwelling pests such as vine weevil larvae, leatherjackets, chafer grubs, or wireworm. Plants often show no above-ground symptoms until damage is severe.