Yellow Celery Leaves: Why does celery turn yellow?

Celery is a cool climate crop that requires a lot of moisture and fertilizer. This demanding crop is susceptible to a number of diseases and pests that can result in a less than optimal harvest. One of these diseases causes yellowing of the celery leaves. So why does celery turn yellow and is there a remedy to help when celery has yellow leaves?

Help, my celery has yellow leaves

As mentioned, celery prefers a cool climate, constant irrigation and abundant food. Celery grows in soil with a pH of 6 to 7 modified with a lot of fertilizer or well rotten manure. The plants are difficult to keep moist, but too much water or wet soil piled around the plants can cause them to rot. These delicate plants also like some shade during the hottest periods of the day.
Even under the most favourable conditions, celery is always subject to a number of problems that can result in celery with yellow leaves. If the celery foliage turns yellow, it may be due to a nutritional deficiency, pest infestation or disease.
If the celery has yellow leaves, the plant may be deficient in nitrogen. The leaf yellowing symptom starts on the older leaves, gradually affecting all the foliage first and causing the plants to stun. Give the celery a nitrogen-rich fertilizer to correct the imbalance.

Pests that cause yellowing of celery leaves

Several parasites can also attack the plague
your celery, which gives yellow leaves.
Not only do aphids cause the leaves to turn yellow, but the leaves also curl up and become deformed. These small yellow to green pear-shaped insects suck nutrients from the underside of the foliage and leave behind their sticky droppings, or molasses. The honeydew, in turn, can lead to the formation of black sooty mould. Try using a strong water spray to kill the pest or use insecticidal soap.
Wireworms, the larvae of the beetles, also cause the celery leaves to turn yellow and turn brown from bottom to top. The growth of the plant atrophies and its health generally declines. The larvae live in the soil, so check before planting. If you see worms with wire joints, flood the soil. If you already have affected plants in the soil, remove them and the surrounding soil before attempting to replant.

Diseases that lead to yellow celery leaves

If the celery foliage turns yellow, it may be the result of a disease. The three most common diseases affecting celery are Fusarium yellows, Cercospora leaf and Celery mosaic virus.

Fusarium yellow

Fusarium yellowing of celery is caused by the soil fungus, Fusarium oxysporum . Commercial growers suffered staggering losses in the fields between the 1920s and the late 1950s, when a resistant cultivar was introduced. Unfortunately, a new strain emerged in the 1970s. The fungus enters the plant through its root system. The severity of the disease depends on the climate, especially hot seasons combined with heavy and wet soils, which can increase the number of spores in the soil. Symptoms are yellow leaves and reddish stems.
The fungus can remain in the soil, inactive, for several years and then, if conditions are favourable, start to recolonize. This means that leaving the soil fallow does not always work. Chemical controls are not promising either. If your plot is infected, try a two- to three-year rotation with onions or lettuce. Do not use corn or carrots, as the fungus will multiply in the root zones of these plants. Destroy all infected plants.
If possible, use resistant or tolerant celery plants. To reduce the risk of introducing fusarium into the garden, disinfect tools and even shoes, remove celery debris, plant in well-drained soil and keep the area free of weeds.

Fence leaf burn

Cercospores leaf blight infection results in irregular yellow-brown spots on the leaves, combined with elongated spots on the stems. This fungal disease is spread by heavy rainfall and warm temperatures. Keep the area free of weeds, which harbour the spores of the fungus, and avoid aerial spraying, which spreads them.

Mosaic virus

Finally, if you have yellow foliage on the celery, it could be the mosaic virus. The mosaic virus is incurable and spreads from plant to plant through aphids and locusts. Destroy any infected plant. In the future, plant resistant varieties and remove weeds that harbour the virus.