Celery Pests and Diseases

Note: the following information is for Apium graveolens var. graveolens (Celery).

To limit losses in the production and quality of the final product, celery farmers should stay alert and inspect their fields throughout the growing season for any pests and suspicious disease symptoms. As always, prevention is much more efficient and usually cost-effective than control-treatment. For this reason, celery farmers are advised to inspect their fields frequently.

Celery Pests

Aphids

Around 12 species of aphids can infest celery, with green peach, bean, willow-carrot, and hawthorn aphids being the most common. Aphids are small, green, or black soft-bodied insects that feed by sucking the sap of plants (leaves, tender stems). This can reduce the growth and yield of the celery plants, especially if the infestation is severe and happens in the early developmental stages of the plants. Additionally, except for the direct damage that the insect cause, it can transmit diseases and contaminate the plant with aphid honeydew. Early control is essential because aphids can develop large populations very fast, especially in moderate temperatures (spring). To control the insect, you can protect the populations of natural enemies of aphids (parasites and predators), and you may avoid planting celery in rotation with carrot, destroy weed hosts, do not overfertilize with nitrogen, and if necessary, spray with suitable insecticides.

Wireworms (Agriotes spp.)

The damage is caused by the larvae of the worm. Newborn larvae scratch the lower surface of the leaves. Grown larvae also get fed on foliage, causing holes in leaves, and stems until they completely destroy the plant. Once the cultivation has been attacked, management is more complicated. Due to the fact that pests quickly develop immunity against pesticides, the best method to control them is through biological management. Chemical treatment is used only if the problem is severe and always under supervision from a local licensed agronomist.

European mole cricket (Gryllotalpa gryllotalpa)

The pest eats the roots of the plant, causing the entire plant to collapse. It also causes severe damage to the hypocotyl reducing the yields significantly. Furthermore, the wounds caused by the pest are susceptible to secondary infections caused by microorganisms. Once the cultivation has been attacked, management is more complicated. Due to the fact that pests develop immunity against pesticides quickly, the best method to control them is through biological management. Chemical treatment is used only if the problem is severe and always under supervision from a local licensed agronomist.

Carrot rust Flies (Psila rosae)

The damage is caused by the larvae, which get fed on the plant’s roots. 1st stage larvae get fed on the roots causing the plants to remain underdeveloped. Infested plants turn yellowing and dry out. The most significant damage, though is caused by 2nd and 3rd stage larvae, which open stoas in the central root, causing severe problems to celery and even death. Infected plants lose their commercial value and are unsuitable for consumption.

Control measures may need to be also taken for caterpillars, two-spotted mites, root-knot nematodes, thrips, leaf-hoppers, lucerne leaf roller caterpillars, leaf miners, cutworms, grasshoppers, snails, slugs and Rutherglen bugs.

Celery Diseases

Disease control begins with proper precautionary measures. These include weed control and safe distances between plants, proper drainage, and avoidance of foliar irrigation. The general condition of the plants (nutrients and water level, sun exposure) can also boost their immunity. Chemical treatment is used only if the problem is severe and always under the supervision of a local licensed agronomist. It is also crucial to use proper sanitation in the plant nursery/greenhouse, such as tools disinfection every time we touch the plants. Some of the most common diseases of celery are:

Leaf/Late Blight

Late blight caused by the phytopathogenic fungus Septoria apicola usually consists of the primary disease problem of celery. The farmer may observe symptoms like small, round, chlorotic spots with an oily appearance on the top of the older leaves that gradually expand, and the leaf dies. Symptoms may appear on the petioles as well. The infection is favored by excellent, wet weather conditions and may threaten celery from early spring to late fall. For this reason, in fields-areas with a known history of the disease, farmers are advised not to use overhead irrigation (e.g. sprinklers). Other important preventive measures are using clean-healthy certified seeds, good sanitation in the greenhouse nursery, and crop rotation with non-host crop species. Finally, when the infection is recorded in neighboring fields, and the weather conditions are favorable for the disease’s spread, a farmer may apply for a regular spray program with appropriate fungicides (e.g., copper oxychloride) (consult your local agronomist).

Pink rot

The disease is caused by Sclerotinia fungi, which can infect celery throughout its whole life cycle. Usually farmers most often observe symptoms in mature plants with well-developed leaf canopies. Some common symptoms are the brown lesions on the petioles that gradually expand into soft, watery, decayed areas covered by white mycelium. In severe cases, the whole plant may collapse. In the case of pink rot, the farmer has very few control measures at his/her disposal. Crop rotation can be helpful in reducing the fungus population in the soil. As prevention measures, the celery farmers may spray the base of the plants with appropriate fungicides, use bigger planting distances to facilitate aeration within the crop and prefer drip irrigation over sprinklers and furrow irrigation.

Fusarium yellows

This is one of the most destructive diseases that can infect celery and significantly decrease the final yield. It is caused by the soil-born fungus Fusarium oxysporum f. sp.apii, which can survive for many years in a field, and even crop rotation has limited control efficiency. A characteristic symptom the farmers can observe in infected plants is the orange-brown discoloration of the xylem in the stems, crown, and roots. The plants appear cachectic, chlorotic/yellowish and gradually die. If the fungus has been found in the soil, it is best not to plant celery in that specific field or use celery varieties resistant to the pathogen (planting in winter or early spring). Finally, since carrots, cabbage, and sweet corn may also be infected by Fusarium, you are advised not to use them in a crop rotation scheme with celery.

Downy and Powdery Mildew

Powdery Mildew is a fungal disease. In infected plants, we observe a light blotch on which a floury (powder-like) coating is then developed, especially on the leaves in the shaded area of the plant. These spots can be expanded to cover the entire leaf while at the same time not allowing the plant to grow. Downy Mildew also causes serious problems. It appears as irregular discolored spots of the foliage of the plants that decrease the quality of the product already from its early stages. Fungicides and the use of resistant celery varieties are effective control measures.

Alternaria spp.

All parts of the plant are affected and at all stages of development. Young seedlings, mainly those derived from the infected seed, die in the early stages. On young plants, we observe dark spots on the stalks, which eventually lead to plant death. On older plants, symptoms appear as brownish spots, first on the lower and then on the upper leaves, with characteristic concentric circles around them. Similar spots appear on the stems and stalks.

Black heart

Black heart is a physiological disorder caused by calcium (Ca) deficiency and is one of the most common problems of celery, especially in fields where there is a surplus of nitrogen and water or under drought stress. For this reason, farmers in areas with ample rainfalls and poorly drained soils prefer to cultivate celery in haygroves or high tunnels.

References

Further reading

Interesting Facts, Nutritional Value and Plant Information of Celery

How to Grow Celery in a Pot in your garden

Growing Celery for Profit – Commercial Celery Farming

Celery Soil preparation, Soil requirements, and Seeding requirements

Celery Water Requirements – How to irrigate Celery

Celery Fertilizer Requirements

Celery Stalk Blanching – How to Blanch your Celery

Celery Weed Management

Celery Pests and Diseases

Celery Harvest and Yields per Hectare

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