Celery (Apium graveolens) is a vegetable species that belongs to the Apiaceae (Umbelliferae) family, being cultivated for its leaves and roots. It is an easy-to-grow species and well-adapted to climatic conditions. The celery crops can be affected by pests and diseases, against which it’s important to apply the right treatments.

The main diseases of celery

Viruses

Celery mosaic virus

Attacked plants have deformed leaves and reduced height. They also show spots of discoloration in the vein area. During vegetation, the virus is transmitted from plant to plant by aphids. Year-to-year transmission is through infected seeds.

Prevention and control measures:

• using certified seeds from reliable sources;
• removing attacked plants from the crop;
• weed control;
• carrying out specific insecticide treatments to control the aphid population.

Bacteriosis

Bacterial Soft Rot (Erwinia carotovora)

The disease makes its appearance in cool summers with heavy rainfall. Moist, yellow-brown patches appear in the crown area. If the humidity remains high, the patches merge and cover the entire root, turning it into a brown, mucilaginous mass. The bacterium enters the plant through wounds caused by maintenance work or insects. The disease can also occur in the storehouse, where it causes extensive damage.

Prevention and control measures:

• correct crop rotation;
• rational irrigation and fertilization;
• sorting the roots before storage;
• growing resistant varieties;
• celery treatments with specific fungicides.

Mycosis

Septoria leaf spot (Septoria apiicola)

It is a very dangerous disease that can completely destroy the plant’s foliage. The attack is favored by temperatures between 18 and 20℃ and high atmospheric humidity. Yellow-brown spots appear on the leaves, bordered by a reddish border. Under optimal conditions, the disease progresses, the spots enlarge, and in the center of the spots appear the fungus fructifications. Symptoms of the disease can appear on stems, inflorescences, or even seeds. Transmission is through infected seeds and fungal spores. They survive in winter on plant debris on the soil surface.

Prevention and control measures:

• using certified seeds;
• gathering and destroying plant debris after harvest;
• celery treatments with specific fungicides.

Powdery mildew (Erysiphe umbeliferarum)

A white or greyish, powdery mycelium appears on attacked plant leaves. Later, small, black dots form on the affected tissues, represented by the fungus’ fructifications. This disease is most common in hot, dry years. The disease is spread by vectors (tools, water, wind, etc.), which carry the fungal spores from diseased plants to healthy ones. In winter, the fungus resists on plant debris on the soil surface.

Prevention and control measures:

• gathering and destroying plant debris after harvest;
• correct crop rotation;
• avoiding sprinkler irrigation;
• celery treatments with specific fungicides.

White mold (Sclerotinia sclerotiorum)

The disease is widespread in all root crops, but the greatest damage is done in warehouses. The disease makes its appearance when the weather is hot and humid. A white fluff appears in the crown area, representing the fungus mycelium, and under optimal conditions, the whole plant can be destroyed. Subsequently, black sclerotia form on the fungus mycelium, which represents the fungus’ resistance organs that ensure year-to-year disease transmission. In the warehouse, the disease spreads through direct contact between attacked and healthy plants.

Prevention and control measures:

• correct crop rotation;
• gathering and destroying plant debris after harvest;
• sorting the roots before storage;
• celery treatments with specific fungicides.

Celery early blight (Cercospora apii)

Small, circular, brownish spots appear on the leaves, slightly sunken into the tissue and surrounded by a thin, brown border. The fungus is transmitted by spores, which live on plant debris on the soil surface causing infection in the following years. High temperatures and the presence of water droplets on the leaves favor the appearance of this disease.

Prevention and control measures:

• correct crop rotation;
• growing resistant varieties;
• avoiding sprinkler irrigation;
• gathering plant debris after harvest;
• treatments with specific fungicides.

Celery downy mildew (Peronospora umbellifarum)

Yellow, watery spots that turn brown appear on the upper part of the leaves. On the underside appears a greyish puff representing the fungus fructifications. This disease can lead in a short time to plant defoliation. Transmission occurs through infected seeds and spores that remain on plant debris on the soil surface.

Prevention and control measures:

• crop rotation;
• growing resistant varieties;
• avoiding sprinkler irrigation;
• gathering plant debris after harvest;
• using healthy, certified seeds;
• treatments with specific fungicides.

The main pests of celery

Striped bug (Graphosoma lineatum)

It has one generation per year and overwinters as an adult in the forest foliage, in orchards, or on plant debris. The larvae and adults attack plants, causing damage to the flower heads, leading to flower abortion, and stopping plant growth.

Prevention and control measures:

• balanced fertilization;
• weed control;
• specific insecticide treatments

Aphids

They are polyphagous species, migrating from one plant to another or from one species to another. These species develop on wild flora and then move to cultivated species. They appear as colonies on the underside of leaves, on flowers or inflorescences, and young shoots. Attacked plants stagnate, turn yellow, and become susceptible to fungal attack. Aphid feeding on plant sap is followed by covering the leaves with their sweet excrement, forming the so-called “honeydew”. This allows the saprophytic fungi to settle and form sooty mold.

Prevention and control measures:

• specific insecticide celery treatments;
• using sticky traps.

Carrot fly (Chamaepsila rosae)

This carrot-specific pest can also attack celery. It develops two generations per year and overwinters as a pupa on plant debris on the soil surface. The females lay their eggs in the soil near the plants. After hatching, the larvae enter the roots, where they dig feeding galleries. Attacked plants die or have their edible parts damaged. Microorganisms can settle in the wounds produced by the larvae leading to tissue rot.

Control methods:

• destroying plant debris after harvest;
• removing attacked plants from the crop;
• treatments during the growing season with specific insecticides;

Phytoecia icterica

This species can attack parsnips, carrots, celery, and other root crops. The pest develops one generation per year and overwinters in the roots of carrots, parsnips, celery, etc. The females lay their eggs in the soil near the roots, and after hatching, larvae enter the roots, where they burrow galleries in the central cylinder. Following the attack, the roots rot. In severe attacks, up to 40% of the crop may be affected.

Control methods:

• gathering and destroying plant debris after harvest;
• correct crop rotation;
• specific insecticide treatments for adults.

Celery fly (Euleia heraclei)

It develops two generations per year and overwinters as a pupa in the soil. The adults emerge in May and lay their eggs on the underside of the leaves. After hatching, the larvae burrow into the leaf, where they dig feeding galleries. The wounds produced are entry points for other pathogens.

Control methods:

• collecting and destroying plant debris after harvesting;
• correct crop rotation;
• periodic crop control;
• specific insecticide treatments.

American serpentine leafminer (Liriomyza spp.)

It is a polyphagous species that attacks almost all vegetable species. The larvae gnaw on spinach leaves in the form of mining galleries, but the attack does not cause significant damage in most cases.

Control methods:

• specific insecticide treatments.

Nematodes 

They are microscopic worms that attack most vegetable species. They develop many generations per year and multiply very quickly. The larvae penetrate the root system of plants and settle in the root vessels. During feeding, they secrete a toxin, which causes tissue hypertrophy. Attacked plants stagnate in growth and eventually dry out.

Control methods:

• correct crop rotation;
• growing resistant varieties;
• disinfecting soil with specific products.