Brown Potato Leaves — What’s Happening?

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Potatoes, including the red varieties, are among the most favorite vegetables across the globe.

While adults enjoy it in various dishes and salads, children often like them when cooked separately as French fries.

The harvesting process of potatoes is fairly easy; however, things can get out of hand if the potato plant begins to develop brown spots. 

 

Brown Potato Leaves

Brown spots on potato leaves, commonly known as potato blight, are one of the most frequent potato plant diseases. This browning can be caused by excess moisture, delayed harvesting, poor garden hygiene, growing disease-sensitive varieties, and inadequate use of fungicides and pesticides. 

 

Potato Blight: All you Need to Know

The phenomenon of Potato Blight, also called Late Blight, was first discovered in South America and spread throughout Europe and other areas through infected fertilizers. 

It occurs due to an infection by a fungus, Phytophthora Infestans, which actively feeds on the potato plant’s leaves and shoots. 

It rapidly multiplies in warm, humid weather leading to the decay of the plant foliage. 

Its spread is not limited to leaves only; it can also adversely affect the plant tubers, encouraging rotting and ultimately making them unfit for consumption and storage. 

Its developing virulent strains pose a significant threat to potato harvesters. 

 

Reasons for Brown Spots on Potato Leaves

 

Excess Humidity

As discussed earlier, surplus moisture around a potato plant is an open invitation to Potato Blight. 

The high humidity, especially in the months of July and August, promotes the quick spread of the Phytophthora Infestans fungus, allowing it to damage large parts of the plant. 

Due to Potato Blight, the affected plant is exposed to several other infections and diseases, making it significantly difficult for it to maintain its health and nutritional value. 

A general rule is to water the potato plant once every four to five days or whenever the plant’s top 1 to 2 inches run dry. 

This schedule keeps the plant adequately hydrated till it is ready for harvest. 

The potato plant should be watered enough that its soil is sufficiently moist, but not saturated. 

Please keep in mind that this plant highly dislikes wet feet and is fast to catch infections in excessively humid conditions. 

 

Late Harvesting

Potato plants are usually ready for harvesting when their foliage turns yellow and shrivels up. 

Next, the leaves dry up, turn brown, and eventually, only the plant’s discolored leaves and dried stems remain. 

When harvested later than September, the potato plant’s leaves mostly develop brown spots or the plant may even lose most of its vitamins and minerals. 

Therefore, ideally, the potato plant should be harvested in late August to mid-September. 

Many potato consumers prefer buying new potatoes instead of the fully mature forms. Make sure to harvest them about a fortnight after the flowering of the potato plants stops. 

 

Poor Garden Hygiene

Keeping up with good garden hygiene is one of the major factors for growing a healthy and happy plant. 

A potato plant that is nurtured and irrigated in a dirty and infectious environment will most likely fall prey to a mild or serious infection. 

Infrequent garden cleaning, late or no removal of weeds, crowding of several plants in a small space, and delay in treating or eliminating diseased plants are all forms of poor plant hygiene. 

All potatoes should be removed at the end of the season; however, this is a little tricky as small tubers can be tough to find. 

The potatoes from the previous season can breed infectious organisms and transfer them to the young potatoes growing close by.

I strongly recommend removing all potatoes as if any potatoes are left, they can cause significant damage to the field, stripping it of its nutrients.

Moreover, please avoid dumping infected potatoes around plants or near your garden. Blight-affected potatoes can be buried in a 10 to 12-inch deep hole and ideally be crushed before burying. 

The Blighted foliage should also be taken away from the young potatoes. 

One way to do this is to compost the leaves in a heap so the spores gradually die. Alternatively, you can put the affected foliage in a plastic bin or bag and get rid of it. 

Besides its surroundings, the plant itself should also be dusted occasionally and its leaves wiped off after watering. 

When clean, the probability of catching an infection decreases considerably. 

 

Disease Sensitive Varieties

While an entirely Potato Blight resistant seed variety has yet not been developed, some types with strong immunity are available. 

These varieties are not completely immune to the disease; however, they remain healthy for relatively longer and do not succumb as quickly. 

Along with using Potato Blight disease-resistant seed varieties, growing the plant in ideal conditions is also essential. 

Frequent watering, adequate moisture, high-quality feed, and exposure to dappled sunlight are some growing tips. 

 

Insufficient Usage of Fungicides and Pesticides

Fungicides and Pesticides, when used in an appropriate amount, turn out to be your best friends. 

The usage of fungicides from time to time limits the growth of fungi, such as Phytophthora Infestans, without causing any significant harm to the potato plant. 

Another traditional fungicide used to control Potato Blight is Bordeaux Mixture, consisting of copper and other ingredients. 

It forms a temporary film on the plant’s leaves, preventing the Blight from spreading further. 

The spraying of Bordeaux Mixture fungicide is more of a preventative solution rather than curative. Using it twice a week is optimal, especially after rain.

However, please refrain from over-spraying; this can lead to the accumulation of copper in the soil which can discourage beneficial earthworms from breeding in the soil. 

 

Quick and Easy Tips to Prevent the Browning of Potato Leaves

• Please avoid overwatering the potato plant. 
• Immediately remove the infected plant from the growing area the soonest you spot signs of Blight. 
• Do not wash the potatoes that you intend to store. 
• Keep your potato plant and its surroundings clean.
• Practice crop rotation. 

 

Frequently Asked Questions about Brown Potato Leaves

 

Can potatoes have Blight recover?

The potato plants affected with Potato Blight are unlikely to recover as the disease causes significant damage to its leaves as well as the tubers. If the affected plant is not promptly removed, the Blight may spread to surrounding plants. 

 

Can I eat potatoes with brown leaves?

While no serious side effects have been reported by eating potatoes with brown leaves, it is better to discard them, especially if large portions seem abnormal or discolored. 

 

Are potato leaves edible?

Many gardeners enjoy eating sweet potato leaves and use them extensively in numerous dishes. However, if you have any allergies to raw vegetables, it is better to avoid eating potato leaves.