Yellowing of potato plant leaves is normal, it’s natural life cycle of a leaf.
Depending on the potato variety, it takes 60-90 days to harvest tubers.
By end of this season, potato leaves starts turning yellow and to prepare for harvest you’re advised to stop watering.
But, your plant leaves can also turn yellow or black due to fungi infestation, disease, nutritional deficiency and overwatering.
As a gardener you must diagnose the plant and save the plant. If left unnoticed, your potato plant may die.
Potatoes are most demanded vegetable and around the world it is 4th most consumed vegetable. This popular vegetable contains vitamins A, C, and B6, calcium, iron, carbohydrates, and dietary fiber.
Harvesting potatoes at home or farm is extremely easy in India where the climatic conditions are just right for its growth.
But as every experienced gardener would tell you, no matter how green a thumb you have, you are bound to be met with notorious pests, hard to cure diseases and growth problems in your journey towards a healthy garden harvest. It is the same with potato plants.
As mentioned above, yellowing of potato leaves by end of the growing season is normal. But a common problem in potato cultivation is the yellowing of potato leaves before the tubers are ready for harvest.
Are you too bothered by this problem? Are your tubers dying before you can harvest them?
Well, do not fret. In this article, we have provided a detailed analysis of the problem and suggested the most efficient solutions to deal with the same. So read on and find out.
Also Read: How Long Does it Take Grow Potatoes in a Bucket?
Best Growing Conditions for Potato Plant
It’s a cool season plant; ideal temperature to grow tubers is 61F to 66F. (Source)
To grow quality tubers, you must maintain optimal temperature. When the temperature increases, tubers stop forming and your plant produce small potatoes.
Adequate sunlight of about 6 hours will help potato plant to produce its food and work on formation of tubers.
Without enough water, your tubers will be poor. In dry weather, you must water potato plants 1 inch per week.
But, don’t let your potato plant to stand in water. Excess water results in rotting of roots and the potato plant may eventually die. Water potato plant when you see 2 inch soil is dry.
Potatoes need a well-drained, deep, loose soil which is high in organic matter. They can be sown all around the year, as cool-season crops in regions of high temperatures, and as summer crops in cooler regions.
However, these plants often show some common gardening problems like wilting of leaves, blight, root rot, scabs and aphid infestations.
These potato growing problems are extremely discouraging and often leave gardeners wondering where they went wrong.
Check this out: Cucumber Plant Leaves Turning Yellow
The most common and confusing problem of all is the sudden yellowing of the leaves which oftentimes leads to death.
Read on to find out more about the nature, cause and solution to this grave problem.
Why Potato Plant Leaves Turning Yellow?
If your potato leaves are turning yellow after 60-90 days of planting, then probably then it is merely a signal that the life cycle of the plants is near its end.
However, if leaves are turning yellow or black before this point, there is enough reason for you to get worried.
You can witness yellow leaves on potato plant because of a wide range of reasons, starting from viral and bacterial diseases to lack of sunlight. Let us look at some of the causes:
1. Verticillium Wilt
The lower leaves of potato plants often turn yellow and wither because of a fungal infection called verticillium wilt. The whole plant gradually becomes yellow as the infection spreads upwards.
This infection also causes the stem end of the tubers to lose their color, and even the stems turn light brown.
This infection reduces the water uptake in the plant and may cause serious water stress.
2. Fusarium Wilt
Another fungal infection taking a heavy toll on the harvest of garden potatoes is the Fusarium wilt.
Even though the symptoms may appear similar, there are various differences between the two that becomes clear upon close observation.
Fusarium wilt causes the tissues between the leaf veins to turn yellow and may even lead to the death of your plants.
3. Pest Infestation
Tiny pests that are less than an inch long can bring sleepless nights to gardeners by causing insurmountable damage to plants.
Potato plants too are susceptible to damage at the hands of these little devils that ruin an entire garden in just a few days.
Potato leaves get discolored and turn yellow because of a pest called psyllids. These pests feed on your plants, and while doing so, release a toxin. This toxin causes a condition called psyllids yellows in which the entire plant gradually turns yellow in color.
Other symptoms include curling up of the leaves closer to the stems and a general stoppage of growth and dwarfism of the plant.
The problem might also be caused by aphids that are small insects living on the underside of potato leaves.
While feeding on your potato plants, they leave a secretion called ‘honeydew’ which turns into a thick, black mould.
4. Nutritional and mineral deficiencies
Potato is a root vegetable, it need to be fertilized more often when compared to indoor plants.
When the growing medium lacks essential nutrients, then this plant starts to show signs of deficiency. Yellowing is one among them.
Every plant would protest if it does not get the required amount of minerals and nutrients from the soil.
Yellowing of the leaves is one way in which your potato plants declare that their nutritional needs are not being met.
Lack of nitrogen is a common cause of pale leaves on potato plants. Nitrogen keeps the soil fertile and helps in the healthy growth and maturity of the plants.
Lack of magnesium can also be a cause of this problem as plants use magnesium to make chlorophyll, the pigment responsible for the green color of the leaves.
Also Read: Is It Bone Meal Good for Growing Potatoes?
5. Potato charcoal rot
Another cause of yellowing of potato leaves is charcoal rot, a soil disease.
This disease also hits several other crops, completely destroying the produce. It is caused by a fungus that develops in the soil under a few very specific conditions.
Charcoal rot affects the roots and the lower parts of the stems of potato plants. In the case of this disease, yellowing of the leaves is among the initial symptoms.
The leaves turn yellow and then wilt, with the rot then spreading out to the stems, and gradually to the roots.
Also read: How deep do potato roots grow?
Plants can survive without fertilizer, but can’t do so without consistent water.
But, this doesn’t mean that you leave potato plant water logged.
Overwatering plants is common among container gardeners. This common gardening problem may cost life of your plant.
You must choose well-drained, loose growing soil. Container in which you’re growing your potato plant must have drainage hole.
Reduce watering frequency to revive the plant. Allow the soil to dry, if needed move the pot to a better sun exposure location.
Once the soil is dried, you can slowly start watering.
Plant leaves are green due to a pigment called chlorophyll. Without sufficient sunlight, leaves lose green color and turn yellow.
Potato plant need at-least 6 hours of sunlight.
Also Read: Why Bitter Gourd Leaves Turning Yellow?
Why My Potato Leaves are Turning Black?
Now that we have talked a great deal about the yellowing of potato leaves, let us come to the next segment. Why potato leaves turning black?
The most common cause of this gravely disheartening problem is frosts and frozen soil. Potatoes are cool-weather crops that are sensitive to frost. Your potato plants can be damaged by frosts even if the temperature does not fall too low.
The damage is not always immediately apparent. Your plants might appear completely healthy the day before, and then suddenly start showing black leaves.
The affected foliage will turn brown at first and then grow completely black before wilting. The wilted part of the plant is dead and would gradually decay.
In case of damage caused by frost or freezing grounds, your plants would not die off completely if the weather improves in a few days.
Even though the affected parts would definitely die, the parts that did not collect frost shall remain alive.
This is because the tubers beneath the soil are not dead.
After the wilted part has decayed new leaves should sprout up within 2 to 10 days of the subsiding of the frost. However, the results would get worse if the weather remains at the extremes for too long.
Check this out: Holes in potato plant leaves
Potato Blight Causes Discoloured Potato Leaves
Potato Blight, both early and late, is a major cause of the discoloration of potato leaves.
This disease initially causes darkening of the edges of the leaves, and with its advent, the black spots keep moving inwards.
Blights can claim a large section of your harvest as they have the power to completely destroy a whole garden within a few days.
Once this disease gets into your garden, all you can do is try to control its spread to the other plants. There is no cure for blights.
Septoria Leaf Spot of Potato Leaves
Septoria leaf spot can also cause the dreaded blackening of potato leaves. This disease does not cause completely visible and prominent dark spots, but black leaves are a common sight among the more common yellow ones.
Stronger and healthier plants do not get affected by this disease very quickly.
But the younger ones are quickly damaged. Therefore this disease is mostly visible in the weaker plants of the lot.
Check this out: When is it too Late to Plant Potatoes?
How to Prevent Potato Plant Leaves From Turning Yellow?
If you did manage to bear with us this far, reading all that we had to say, you now know enough about the nature and cause of the discoloration of potato leaves.
Knowledge might be power, but mere knowledge cannot solve your problems. You need to act on them.
Here is how you can solve the problem of potato leaves turning yellow and black:
Before that, I recommend to read this: Why Are My Potato Plants Falling Over?
#1 Growing soil
In case the cause of the problem lies in the soil, you would need to have it tested. If your problems are being caused by a lack of minerals you need to treat it by adding fertilizers.
If your plants are lacking in nitrogen, add a nitrogen-based fertilizer. If the problem is a lack of magnesium, choose one rich in magnesium instead.
#2 Avoid fungal infection
If the cause of the problem is fungal infection and wilt, the best thing to do is to take preventive measures.
This is because even though fungicides are successful in curing the disease, it is not always effective and the quality of the harvest is compromised.
#3 Choose best potato seeds
To take preventive measures, purchase a variety of potato seeds that are stronger and more resistant to diseases.
After a season of wilt infection, rotate the crops with legumes, grasses and cereals to prevent the problem from occurring again.
Rotating the crops for a period of four to six years is essential for treating the soil, restoring its minerals and killing off all the pathogens that cause infections in your plants.
For issues with frost and frozen ground, you don’t have much to worry about.
Potato plants are generally adaptive to adverse climatic conditions and would probably survive the cold as long as it subsides within a few days.
After the frost subsides, your plants would shed off the damaged parts and new seedlings would emerge within 2-10 days.
If your plants have been infested by aphids, spray them away using a powerful garden hose.
Spray water on the potato plants with a strong blast, and if possible use a mild insecticidal soap.
In the case of pest infestation, organic gardeners are often unwilling to use pesticides as that compromises the quality of the produce.
Spinosad, an organic compound based pesticide is the perfect solution to this dilemma.
Use this pesticide to get rid of all the pests that have been disturbing your plants.
#7 Break disease cycle
Clean seed potato stocks can be created by the process of tissue culture. These seeds have attained considerable success in breaking the cycle of diseases in potato plants.
Purchasing these varieties of seeds can ensure a healthy, fresh batch of potatoes every season, saving you the trouble of combating diseases.
Use of protective fungicides can help you in reducing early blight.
Be sure to fertilize and water adequately, as these steps can reduce the stress of the plants and make them more immune to diseases.
A well cared for and the healthy plant is less likely to catch diseases compared to neglected ones.
You can also plant late varieties of potatoes that are hardy and less susceptible to diseases.
Use furrow irrigation instead of sprinkler irrigation and avoid overwatering at all costs. This can help in reducing the severity of the fungal diseases, should they occur.
Also Read: Can You Plant Potatoes that Have Sprouted?
Pest, fungal infection, disease, low levels of nutrients, insufficient sunlight and excess water can cause yellowing of potato plant leaves.
It’s heart wrenching to see leaves of potato plant turning yellow before the harvest time.
If you’re monitoring your plants regularly, then you can revive the plant.
After seeing early signs of yellowing, you must diagnose the plant and try to revive it.
Hopefully, all the information we provided above will help you identify and solve your problem and you would no longer be left wondering why are my potato plants turning yellow and dying.
You must, however, keep in mind that even under ideal circumstances, potato plants are not invincible. They are very susceptible to pest infestations and several other diseases.
Taking care of your plants is all that you can do. There are a number of diseases that cannot be managed and once infected; your plants are bound to get damaged.
In most of such cases if you provide the required care to your plants their chances of getting infected are reduced. The key to a healthy harvest, therefore, is to care for your plants, watching over them as they gradually grow and mature.
Although this might seem to be an arduous task, the results are going to be really satisfying. Harvesting a healthy batch of potatoes from your own backyard garden is a feeling cherished by home gardeners all across the world.