9 Potato Plant Diseases to Watch For This Season

Symptoms show up on mature foliage first in the form of dark brown lesions. They can be circular or angular, and sometimes concentric rings appear, creating the look of a target. Eventually, the infected leaves will turn yellow and ultimately fall off. The tubers turn brown and have a corky texture.

Keeping your plants healthy is the best prevention, as it won’t do as much damage to a strong crop. Fertilize regularly to keep a steady supply of nutrients, and make sure to manage pests. Proper watering is a must, as soggy conditions are the most likely way to spread it.

As soon as you notice symptoms, apply a fungicide to mitigate the damage. If you get to them early enough, this is an effective treatment. Repeat the application a couple of times at seven to ten-day intervals.

Initially, water-soaked spots will show on the lower leaves. As the lesions grow, if the weather dries, they turn brown in the center. The white edges indicate that the disease is actively proliferating. After the weather dries, the edges of the lesions turn yellow, and severe infections can cause a particular odor.

Good plant hygiene is the best prevention. Water sparingly during times of wet and misty weather. Avoid overhead irrigation, and practice crop rotation with a crop unaffected by the disease, rotating out of areas where the blight was present. Inspect plants regularly and remove any with serious damage to prevent spreading to healthy plants.

Some varieties are more resistant than others, so try to choose these when you get started. Thin out the plants, allowing for better air circulation to stem the spread of spores.

Symptoms include wilting, especially on one side before moving to the other, and leaves that turn yellow from the lower leaves upward. Tissue near the soil may darken before plants die off, typically before reaching maturity.

Start with disease-resistant varieties from a reputable source. Rotate crops, as this pathogen can live in the soil for over a decade. Keep your potatoes fertilized and watered to reduce stress and maintain good plant care.

The Trichoderma fungus can act as a biological control for verticillium wilt, but this is hard to find commercially. It can inhibit the growth of the disease and promote plant health. Larger farms may have luck with soil fumigation, but this requires buffer zones that aren’t possible to attain in home gardens. Affected plants should be removed and disposed of ASAP.

You can identify this disease by the reddish-brown lesions that it leaves on young stems and sprouts, and cankers on stems, both old and new. In some cases, aerial tubers may grow above ground.

Use disease-free seed from a reputable source. Plant your potatoes in warm, dry soil and avoid over-watering. Remove vines as soon as they die back to prevent proliferation of the disease in soil.

Soil fungicides can be effective, and some biological controls, such as Trichoderma, also help, though there are not many forms of Trichoderma available to home gardeners. Rotate crops yearly, only planting nightshades every second year.

You’ll see the effects in the stems first, as they turn black and mushy. If you pull on them while wet they will pull away from the soil easily and feel slimy. In dry weather, they will become brittle and hollow. In tubers, soft, wet, cream-colored rot may also have sunken tan spots and an orange liquid ooze may be present.

Buy from a trusted source, and handle your tubers gingerly. Avoid bruising or cutting into them. Keep your tools clean, and make sure you plant in a space with good drainage. Wait until the soil warms to 50°F (10°C) before planting.

Dig up any affected tubers right away and dispose of them. Don’t compost, as the bacteria can live in your compost. Make sure to wash your potatoes before storing, and cure them at high humidity and cool temperatures to help stop rot.

The name says it, this virus causes the younger leaves to roll upward along the margins. The affected foliage may be light colored and feel dry and crunchy. Once it reaches the mature foliage the plant, and tubers are most likely stunted.

Controlling aphid populations is paramount, and sourcing your tubers from a reliable source. However, it’s difficult to control once the aphids are present. Reflective mulch can deter them. Dispose of plant waste properly, and don’t leave potentially diseased foliage on the ground.

There is no direct treatment, so preventing its spread is the best direction to take. Get aphid populations under control by attracting beneficial predators and using manual removal or other pollinator safe removal methods.

Aside from the obvious brown ring in the tuber, it affects the vascular system of the plant. The leaves may discolor and wilt, and the tubers will most likely rot.

Plant your tubers whole, don’t cut them into pieces. Rotate crops every second year, and use good gardening hygiene and clean tools. Pull up any volunteer potatoes.

There are no known controls for this disease, so prevention is key.

The first signs are water-soaked lesions on the stems near the level of the soil. These spots develop a white mycelium, and gradually, they will expand. Sclerotia will develop inside the rotting tissue, and the plant may wilt due to stem girdling.

Crop rotation goes a long way in preventing this and most other diseases. Avoid overwatering, especially during times of excessive rain. Avoid over fertilizing as well, because excess foliage can become crowded and prohibit air circulation.

Foliar fungicides are an effective treatment for white mold, but these are systemic and typically less available to home gardeners. Those that contain fluopyram are particularly useful, but again, it is better to simply remove the plant and dispose of it in a home garden. Use of system fungicides on a smaller scale requires a buffer that smaller gardens may not be able to attain.