Late Blight Disease In Celery: How To Manage Celery With Late Blight

By: Mary H. Dyer, Credentialed Garden Writer

What is celery late blight? Also known as Septoria leaf spot and commonly seen in tomatoes, late blight disease in celery is a serious fungal disease that affects celery crops across much of the United States and around the world. The disease is most troublesome during mild, damp weather, especially warm, humid nights. Once late blight on celery is established, it is very difficult to control. Read on for more information and tips on how to manage late blight on celery.

Symptoms of Late Blight Disease in Celery

Celery with late blight disease is evidenced by round yellow lesions on the leaves. As the lesions get larger, they grow together and the leaves eventually become dry and papery. Late blight on celery affects older, lower foliage first, then moves up to younger leaves. Late blight also affects stems and can ruin entire celery plants.

Tiny, dark specks in the damaged tissue are a sure sign of late blight disease in celery; the specks are actually reproductive bodies (spores) of the fungus. You may notice jelly-like threads extending from the spores during damp weather.

The spores spread rapidly by splashing rainwater or overhead irrigation, and are also transmitted by animals, people and equipment.

Managing Late Blight Disease in Celery

Plant resistant celery varieties and disease-free seed, which will reduce (but not eliminate) late blight on celery. Look for seed at least two years old, which is usually free of the fungus. Allow at least 24 inches (60 cm.) between rows to provide ample air circulation.

Water celery early in the day so the foliage has time to dry before evening. This is especially important if you irrigate with overhead sprinklers.

Practice crop rotation to prevent the disease from accumulating in the soil. If possible, avoid planting other vulnerable plants in the affected soil, including dill, cilantro, parsley or fennel, for three growing seasons before planting celery.

Remove and dispose of infected plants immediately. Rake the area and remove all plant debris after harvest.

Fungicides, which don’t cure the disease, can prevent infection if applied early. Spray plants immediately after transplanting or as soon as symptoms appear, then repeat three to four times per week during warm, humid weather. Ask experts at your local cooperative extension office about the best products for your area.

This article was last updated on

What to Do With Potatoes and Tomatoes Infected With Late Blight

Alan Buckingham / Getty images

Every gardener knows that no plant, vegetable, fruit, or flower is completely immune to disease or infestations. All you can do is take the proper preventative measures to keep your plant safe, and know how to deal with a diseased plant if you end up having one.

Two well-loved garden heroes, tomatoes and potatoes, are especially susceptible to an affliction known as late blight. Characterized by large, irregularly-shaped, greasy gray spots (and even soft rot), late blight is a serious plant affliction that led to the Irish Potato Famine in 1845. Although plants infected with late blight tend to die quickly, you can often salvage some of your tomatoes and potatoes from the plant before they meet their fate thanks to these tips for dealing with late blight.

What Is Celery Late Blight - Recognizing Late Blight On Celery Plants - garden

There are a number of diseases and pests that can potentially harm your celery crop. Luckily, there’s a fairly simple solution to avoid most of these issues: plant a less-vulnerable variety like Tall Utah.

Below, we've listed common diseases and pests, and what you can do to either avoid or fix the issue!


Bacterial blight:A disease causing small water-soaked spots to form on the leaves that are circular or angular in shape.

Soft rot: Small water-soaked lesions will form that become soft, sunken and brown. The bacteria for this disease will enter your plant through wounds (like tears in the stem), and it usually comes out when soil has been water-soaked for a long period of time.

Celery mosaic: The leaves may be twisted, curled or cupped, and young plants may be stunted. This virus is transmitted by several types of aphid pests, and symptoms usually develop within 10 days or so.

Damping-off: A disease causing soft, rotted seeds that fail to germinate. The fungus can be spread three different ways, either in water, by contaminated soil, or on your equipment.

Early blight:Small yellow spots will form on the upper and lower leaf surfaces, which then grow into brown-grey spots with a papery texture. Typically, this disease thrives in warm temperatures and high humidity.

Downy mildew:At first, this disease causes leaves to turn yellow, typically starting from the main vein then spreading outward. Fungal spores (ew!) will then grow on the undersides of leaves, appearing as gray to almost purple fuzzy spots. Downy mildew typically affects young, tender leaves.

Late blight: You’ll notice black spots that look like peppercorns embedded in the leaf tissue. It becomes a problem when heavy rainfall and dense leaf canopies keep your plants from drying properly.

Fusarium yellows: Yellowing plants that are severely stunted, with brown, water-soaked roots. This fungus can survive in your soil indefinitely once it’s there, and it’s usually introduced by infected transplants or contaminated equipment

Pink rot:Soft brown lesions on the base of celery stalks that cause the surrounding area to turn pink. Later, large black spots will develop on the infected spot. Typically, pink rot is caused by soil that’s been heavily wet for more than two weeks.

Powdery mildew:White patches that start on older leaves and eventually spread to other plant parts. It’s brought on by high humidity and moderate temperatures, with symptoms becoming most severe in shaded areas.


Armyworm: Larvae that heavily feed on leaves, turning them into “skeleton” leaves. These pests are most active in the early morning and the late evening, which are the best times to check for damage.

Aphids:Usually green or yellow, but they can also be pink, brown, black or red. A heavy infestation may cause your celery leaves to appear yellow and distorted. Sooty mold can also develop as a result of the sugary/sticky substance they leave behind.

Nematodes:Microscopic worms that live in soil and plant tissue. They stunt your celery’s growth, and cause galls (swelling growths)
to form on the roots. Because of their wide host range, it’s difficult to manage this disease sufficiently.

Black heart:This disease appears as black spots in the middle of the plant, and the damage typically isn’t visible until later in the season. Black heart is a nutrient imbalance that’s caused by a calcium deficiency

If you're having an issue with your celery that wasn't listed above, be sure to let us know! Send us a message so that we can help your plants thrive :)

PS. Want tips and tricks for growing a variety of herbs and vegetables? Sign up for our newsletter, and stay informed about all things gardening. You'll receive helpful, step-by-step tips to help make your garden a success!

Identifying Harmful Celery Diseases

The celery plant is commonly grown among household, vegetable gardens. Its succulent leaves are cooked fresh and its seeds are used as a flavoring agent. Celery has a longer growing season compared to most other garden plants. This makes the celery crop susceptible to many diseases that can be very destructive. For effective disease management, identifying the initial symptoms is critical. You can use the following information for identifying and controlling the two most harmful diseases common to the celery crop.

Celery Rot Disease

This disease is more common in cold and moist conditions. It is caused by the common soft rot bacteria, called E. carotovora. It mainly affects the stem of the celery crop. A more typical form of the Soft Rot celery disease is Pink Rot. Although this is also a stem-based disease, it is caused by a fungus and not bacteria. Soft Rot and Pink Rot are commonly referred to as Rotting Diseases.


Soft Rot and Pink Rot-affected celery crop show some common symptoms. The affected part of the stem has a typical, water-soaked appearance. The stem appears slimy, showing signs of initial decay. Some stems may even emit a rancid odor. Soft rot bacteria spreads quickly through the celery crop, particularly through stems that have been weathered due to harsh winter conditions. The identifying features for an invasive Pink Rot disease include rapid decaying of the basal part of the stem, with the decaying area developing a slightly pinkish hue. Sometimes, the pink core is surrounded by a white mold.


Crop rotation is helpful against Soft Rot. However, Pink Rot needs more invasive management, like spraying the seedbed with fungicides. You should rotate the celery crop to ensure that the Pink Rot doesn't become invasive in one part of the garden. Try to irrigate with the drip method instead of using sprinklers, water sprayers or furrow irrigation. This helps to reduce chances of stem injury due to pressurized water spraying.

Celery Blight Disease

Leaf blight is also called the leaf spot disease. It is caused by two types of fungi — Cercospora and Septoria fungus. Both the types of fungi favor wet, colder conditions. Heavy rains and strong air currents can aid the spread of such fungi. Cercospora Blight and Septoria Blight are commonly referred to as Spotting Diseases.


Septoria Blight is also called Late Blight. It has a long dormant stage before it becomes visible to the human eye. You should carefully inspect your celery crop for Late Blight symptoms, like appearance of specks among the lower leaves. Septoria-affected leaves have a dull, brownish appearance. Septoria blight develops in the form of small flask-like bodies found around the leaf lesions. Cercospora Blight occurs more commonly and is easier-to-spot. It is also called Early Blight. It can occur in humid conditions as well, whereas Septoria blight needs extremely wet environments. Early blight does not have any spore-like formation, but the necrosis among the leaves is easily observable.


You should start using fungal sprays as soon as you transplant celery into the garden soil. Most spotting diseases are caused due to dormant fungal spores present in the seeds bought from garden supply stores. You should soak the seeds in an anti-fungal solution before sowing them. You should try to rotate the fungal formulations to ensure that the fungi don’t become resistant to any particular kind of fungicide. If your crop shows a repeated pattern of blight infestation, three-to-four crop rotations in a year are recommended. Try to widen the gap between the rows of plants to ensure better inflow of air. This helps to displace the fungal spores.

Watch the video: Late Blight. Phytophthora infestans. How to identify Late Blight

Previous Article

Information About Leyland Cypress

Next Article

Columnar apple tree: planting and care, pruning, description of varieties for the Moscow region, photo