Causes of potato leaf curling, treatment methods and control

Potato leaf curl is a problem that needs to be noticed and addressed promptly, otherwise you could lose your crop. Let's look at the main reasons why this might happen.

Description of the causes of leaf curling

Leaf curl is often just one sign of a problem. It's usually accompanied by other symptoms of disease or damage. So, what could be the causes of leaf shape changes?

The most common are diseases and herbicide damage. However, leaf curl can also be caused by many other issues. In this article, we'll cover each of them in detail.

Diseases

Potatoes are susceptible to a variety of diseases, and leaf curl is just one of them. Let's explore these potential diseases in more detail to save your plants in time.

Viral diseases

The main viral diseases are called potato mosaics. There are several types of mosaics, and often a single plot is infected with several types at once.

Wrinkled mosaic

With this disease, wrinkles, swellings, and yellow spots appear between the leaf veins. The leaf then begins to curl and bend, and eventually droops without falling off. The affected plant fails to bloom, has stunted foliage, dies prematurely, and the tubers remain small. Yield losses from rugose mosaic can reach up to 90%.

Affected bushes should be immediately removed from the site and burned. The best control method is a comprehensive preventative approach, including selecting healthy and resistant planting material, weeding, and pre-planting germination.

Striped mosaic

Signs of the disease include dark spots on the leaves, curling, and dark streaks on the leaf veins. These symptoms first appear on the lower leaves, then spread to the middle and upper leaves. The leaves dry up and die, leaving only a couple of branches at the top of the bush. Tubers fail to develop, and yields are significantly reduced.

This problem needs to be dealt with in the same way as with wrinkled mosaic.

Fungal diseases

Often crops become diseased due to fungal infection.

Late blight

If leaves have started curling and brown spots have appeared, gradually spreading to the stem, it's possible you're dealing with late blight. The main symptom is a white coating on the underside of the leaves, caused by fungal spores. The tubers also become covered in dense spots. The fungus that causes the disease spreads very quickly to neighboring plants.

Late blight is very difficult to eradicate: all affected bushes must be removed, and the remaining ones require chemical treatment. Oxychom and Ridomil MC are suitable for this purpose. These products accumulate in potatoes, so it's best to use preventative measures. These include potassium and phosphorus fertilizers, wood ash, garlic infusion for spraying, and hilling. It's also important not to plant bushes too close together, practice crop rotation, and plant nightshade crops separately.

Scab

The skin of healthy potatoes is smooth and thin. If certain areas darken, become thicker, and harder, or the entire potato begins to crack and scab, the potato is infected with dangerous scab. Sometimes, the entire affected tuber becomes covered in dense scab spots. The flesh of the potato begins to rot. Brown spots appear on the stem, and the leaves curl, darken, and dry out.

Scab is a common disease, yet many gardeners ignore infected tubers. It can cause up to 40% crop losses, so it's important to take action promptly.

Crop rotation and formalin treatment are the best methods for controlling the disease. Phosphorus fertilizers and Thomas slag, soil amendments with sulfur dye, and careful seed selection are also helpful.

Herbicide damage

Leaves can curl due to herbicide-based products that many gardeners use to control weeds. The problem can even arise if your neighbors, not you, are using these products—harmful components can be carried by the wind from neighboring plots.

To avoid problems, choose potato varieties that are resistant to herbicides. If the variety is sensitive, it's best to avoid treatment. The Saite and Yavar varieties are particularly susceptible.

Mosaic leaf curl

The cause of this problem is an attack by aphids or field bugs. The disease is a type of mosaic.

During the budding period, the edges of the upper leaves become wavy and raised. The top of the bush takes on the appearance of a spoon or flower bud. Typically, by the end of the growing season, the leaves straighten out, but the fruit has already been damaged. The tubers lose a large amount of starch, lose flavor, and remain small. Sometimes, losses can reach up to 40% of the harvest.

The disease must be treated in the same way as other mosaics – with quality prevention.

Why do potato leaves curl?

Remember that potato leaves curl for a reason. Don't leave your plants unattended. Healthy leaves should be a uniform green color, unblemished, smooth, and never curled.

So, the main causes of leaf curling are fungal and viral diseases, and herbicides. Sometimes leaves change shape due to unfavorable environmental conditions: lack of moisture, heat or cold, or a lack of nutrients. But if the climate, humidity, and fertilizer levels are normal, the curling is most likely caused by disease.

How to prevent curling

To protect your crop from the main problems that cause leaf curl, preventative measures are necessary.

1. Choose robust varieties that are resistant to diseases and pests.
2. Carefully inspect the planting material for diseases and damage. Remember, it's best to plant whole tubers without cutting them.
3. At the first sign of suspicion, remove all infected bushes from the area.
4. Fertilize, moisten and loosen the soil on time, and provide proper care for the plantings.
5. If an infestation occurs, use chemicals that target the specific problem.
6. Also, treat potatoes with protective products before planting and periodically afterward. Choose them wisely: for example, if potatoes in your area are often susceptible to scab, consider using preventative products.

Reviews

Gardeners are actively discussing the curling problem. Let's find out what they're writing about it on forums.

Anastasia writes:

"Many factors can influence this. If the leaves are curled, it could be a virus, fungus, or improper herbicide application. Or perhaps there's simply a nutrient deficiency. It's best to call a professional; they'll figure it out."

Victor writes:

"My leaves were curling, but I dug them up and sold them anyway in the fall. I saved them by digging up a few bushes and inspecting them carefully. The roots and stems were fine, and the previous year there had been a good harvest. I realized it was due to the herbicides, stopped using them, and everything went away. Now I just weed by hand, even though it's hard..."