Cilantro Has White Coating On Leaves: Managing Cilantro With Powdery Mildew

Cilantro Has White Coating On Leaves: Managing Cilantro With Powdery Mildew

By: Bonnie L. Grant, Certified Urban Agriculturist

Powdery mildew is a common fungal disease among vegetables and ornamental plants. If your cilantro has white coating on leaves, it is very likely powdery mildew. Powdery mildew on cilantro is most prevalent in moist, warm conditions. Periods of high humidity, overhead watering and overcrowded plants are likely to lead to powdery mildew on cilantro and many other plants. Learn what to do to control and, if possible, prevent the disease.

Identifying Cilantro Powdery Mildew

White, fluffy growth on the leaves of a cilantro plant signify an outbreak of a fungus, powdery mildew. Powdery mildew of cilantro is unlikely to kill the plant but does make it less productive and the leaves can develop an “off” flavor. The fungus appears on leaves and stems. Simple cultivation tips early in the season, as well as an understanding of why powdery mildew on cilantro occurs, can help nip this fungus in the bud.

Powdery mildew of cilantro shows up when weather is warm but the foliage comes in contact with moisture that does not dry in an adequate amount of time. This could be from watering the plant overhead, or from nighttime dew or rain. When moisture gets on leaves and remains there for several hours before drying off, the fungal spores have time to germinate and spread.

The initial signs are usually just a few spots and can be hard to find, but in just a few days the entire leaf surface may be covered in fine white dusty spores. The spores will shake off to some degree, but the bulk of them will still coat the leaf. Washing them off does not work either, as it will wet the leaf and start the process anew.

Preventing Cilantro Powdery Mildew

Once you have discovered that cilantro has white coating on leaves, you need to move onto control measures. However, if this happens to you every year, it is time to think about prevention.

Choose a location for planting that gets good sun exposure. The spores and mycelium of powdery mildew are very sensitive to sunlight. Select a resistant variety of cilantro if possible, and when planting cilantro, make sure there is plenty of space around each plant so air can circulate.

Use drip irrigation to water the roots and not the foliage. If you do water overhead, water in the morning so leaves can dry quickly.

Remove any infected part immediately to help prevent the spread of the disease. In most cases, it takes 7 to 10 days to complete the disease cycle but it can occur in ideal conditions in as little as 72 hours.

Controls for Cilantro with Powdery Mildew

Sulfur foliar spray is effective against powdery mildew. Spray every 7 to 14 days to prevent the fungus from growing. A mixture of garlic crushed in water is high in sulfur and non-toxic.

Baking soda dissolved in water is an effective natural fungicide because it changes the pH on the leaves, making it less hospitable for the fungus.

Because the leaves of cilantro are edible, it is best not to use any professional fungicide sprays. Some gardeners also swear by wetting the leaves with diluted compost tea or urine to prevent mildew from growing.

If all else fails, remove the affected leaves and destroy them. Cilantro grows quickly and a fresh, unaffected crop will arrive in no time.

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How to Identify Powdery Mildew

  • Plants infected with powdery mildew initially show circular, powdery white spots on the upper sides of the leaves.
  • These spots can then spread to the undersides of the leaves, stems, buds, and sometimes the fruit, making your plants look as if they have been dusted with flour.
  • The leaves, buds and growing tips can then turn yellow and dry out, or become twisted and disfigured.

How To Grow And Care For Cilantro In A Pot

Cilantro is a highly aromatic herb that is used to enhance the flavor of many South-East Asian and Mexican cuisines and as a dressing to improve the appearance of meal served. Some people consider that growing it is difficult but we don’t agree with that, you just need some smart tips.

How To Grow Cilantro From Seeds

Take a pot of 18 inches wide and at least 10-12 inches deep, sow your seeds it’s very difficult to transplant cilantro, so use a single pot. Sow seeds 1/4 inches deep. Keep the soil moist until the seedlings germinate.

When To Plant Cilantro

Start cilantro once all the dangers of frost are passed. You can grow cilantro successively from spring to fall.

Best Soil For Growing Cilantro

Neutral soil that is very rich in organic matter and crumbly in texture helps this plant to grow. Also, the addition of aged manure or compost provide a good steady supply of nitrogen and other trace elements, thus promotes the vegetative growth.

How To Care For Cilantro

It is a plant that grows best in the sun. But be careful, too much heat will make it go to seed quickly. In summer (or in warm climates) place it in a position that receives shade in the afternoon. Cilantro likes evenly moist soil. When watering, make sure you never wet the foliage as cilantro is really susceptible to powdery mildew. Feed the cilantro bimonthly with any half strength nitrogen-rich fertilizer to promote the foliage growth. You don’t need to fertilize your cilantro plants much if you side dress them with compost or manure. Also, the application of fish emulsion is recommended.

When To Harvest Cilantro

You can start to harvest young cilantro leaves too early, about 3-4 weeks after sowing seeds. Leaves can be picked from the plant when they have reached 3-6 inches in length. If you want to harvest the entire plant you should wait at least 45-70 days. Cutting the entire plant at soil level or 2 inches above the crown.

Pests and diseases that affect cilantro

Herbs tend to have a stronger defense against pests and diseases than other plants. But they still can be affected.

Growing in pots helps to keep the cilantro plants isolated from the other plants in the garden. This also helps lower the chances of the plants getting affected by pests and diseases.

The best way to keep fungal diseases away from cilantro is to avoid splashing water on the foliage. And growing it in a place that has good air circulation.

The benefit of growing in containers is you can monitor the plant every day as part of your watering schedule. If you find a pest or disease, you can take immediate steps before it becomes a full-blown problem.


Aphids: These are small sap-sucking insects that come in different colors like green, white, yellow, red, orange. It’s easy to get rid of aphids by spraying them with water and dropping them to the ground. Or using insecticidal soap on the affected parts of the cilantro plant.

Cutworms: These are larvae of adult moths that may be solid, spotted, or striped. They come in colors like grey, pink, green, black. They damage the plant by eating the base of the stem and roots causing the plant to die. You can protect your plants from cutworms by covering the stem with a toilet paper tube.

Root-knot nematode: These are microscopic worms that are present in the soil and feed on the cilantro plant’s roots. The roots develop irregular or rounded galls. The only solution is to dispose of the affected cilantro plant and potting soil.


Bacterial leaf spot: This is a bacterial disease that causes black or brown spots on the leaves. The spots increase in size and the leaves may wilt and fall off. There is no solution to this disease. You can prevent it by avoiding splashing water or soil on the foliage. And by selecting a cilantro plant variety that is resistant.

Powdery mildew: This is a fungal disease that infects the plants causing white-gray powdery growth on them. A severe infection will cause the leaves to brown and drop. You can prevent this problem by avoiding splashing water or soil on the foliage. Or cut off the leaves that have been infected.

Soft rot: This is a disease caused by bacteria and a moist environment makes the cilantro plant susceptible. It causes the plant tissue to become soft and wet. Avoid splashing water on the foliage to prevent this disease. Take care not to damage the cilantro when pruning or harvesting.

Watch the video: Easy, Inexpensive Powdery Mildew Spray for Squash u0026 Cucumbers, Prune Leaves to Keep Production Going