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Sweet Potatoes pests and diseases

Published: 09.04.2023
Pest/Disease Type Symptoms on Sweet Potato Control/Prevention
Sweet Potato Weevil Insect C-shaped tunneling in sweet potato Practice crop rotation, use insecticides or nematodes
Whiteflies Insect Sticky residue on sweet potato leaves Use sticky traps, neem oil, or insecticidal soap
Sweet Potato Leaf Beetle Insect Skeletonized leaves with small holes Handpick or use insecticides
Cutworms Insect Cut stems at soil level Use collars around plants, handpick or use insecticides
Sweet Potato Scab Bacterial Rough or scabby patches on sweet potato skin Plant disease-resistant varieties, maintain proper soil pH and moisture levels
Fusarium Wilt Fungal Yellowing and wilting of leaves, brown discoloration of roots Practice crop rotation, use disease-resistant varieties, maintain proper soil drainage
Stem Rot Fungal Dark, watery lesions on sweet potato stems Practice crop rotation, maintain proper soil moisture levels, use fungicides
Root Knot Nematodes Nematode Swollen, knotted roots on sweet potato plants Practice crop rotation, use resistant varieties, use soil fumigants or nematode-resistant rootstocks
Southern Blight Fungal Brownish-yellow lesions on sweet potato stems, wilting and collapse of plant Practice crop rotation, maintain proper soil drainage and moisture levels, use fungicides

Sweet Potato Weevil

Sweet potato weevils are small beetles that are one of the most common pests affecting sweet potatoes. These insects bore into the sweet potatoes and lay their eggs, which hatch into larvae that feed on the flesh of the sweet potato. This can lead to severe damage and reduced yields.

Symptoms: The most obvious symptom of sweet potato weevils is the presence of small, round holes on the surface of the sweet potato. These holes are caused by the adult weevils as they bore into the potato to lay their eggs. Infested sweet potatoes may also develop a soft or mushy texture, and may emit a foul odor.

Control/Prevention: The best way to control sweet potato weevils is through prevention. When planting sweet potatoes, choose certified disease-free plants and rotate crops each year to reduce the risk of infestation. Additionally, remove any infested sweet potatoes from the garden immediately to prevent the larvae from spreading to other plants. Insecticides can also be used, but should be applied according to label instructions and with caution to avoid harming beneficial insects.

Overall, by taking preventative measures and being vigilant in monitoring for signs of infestation, gardeners can successfully control sweet potato weevils and protect their crops.


Whiteflies are a common pest that affects sweet potatoes and other plants in the garden. These tiny, white insects are often found on the undersides of leaves and can cause damage by feeding on plant sap.


One of the first signs of a whitefly infestation is the presence of small, white insects on the undersides of leaves. As the infestation grows, plants may begin to show signs of stress, such as wilting or yellowing leaves. The sticky residue left behind by whiteflies can also attract other pests and lead to the growth of sooty mold.

Control or Prevention

Prevention is key when it comes to whiteflies. Regularly inspecting plants for signs of infestation and removing any affected leaves can help keep populations in check. Introducing natural predators, such as ladybugs or lacewings, can also be effective in controlling whiteflies.

If an infestation does occur, insecticidal soap or neem oil can be used to control the population. However, it's important to follow the instructions carefully and avoid using these products during the hottest part of the day or when plants are under stress.

Overall, by taking proactive measures to prevent whitefly infestations and promptly addressing any issues that do arise, gardeners can help keep their sweet potato plants healthy and thriving.

Sweet Potato Leaf Beetle

The Sweet Potato Leaf Beetle is a common pest that can cause significant damage to your sweet potato plants. These small, bright orange beetles are approximately 1/4 inch in length and have black spots on their wings. The larvae of these beetles are even more destructive, as they feed on the foliage of sweet potato plants and can quickly defoliate an entire plant.

The symptoms of Sweet Potato Leaf Beetle infestation include small holes in the leaves, skeletonization of the leaves, and yellowing of the foliage. In severe cases, the leaves may drop prematurely, leading to a reduction in yield.

To control or prevent an infestation of Sweet Potato Leaf Beetles, there are a few things you can do. Firstly, you can use a physical barrier such as row covers to prevent the beetles from accessing your sweet potato plants. Secondly, you can use organic insecticides such as neem oil or pyrethrin to control the beetles. Finally, you can encourage natural predators such as ladybugs or lacewings to feed on the beetles and their larvae.

In conclusion, Sweet Potato Leaf Beetles are a common pest that can be controlled with proper prevention and management techniques. By being vigilant and taking action early on, you can protect your sweet potato plants and ensure a healthy and abundant harvest.


Cutworms are common pests that attack sweet potatoes during their growing season. They are the larvae of several species of night-flying moths and are usually found in the soil. Cutworms cut down the young seedlings at ground level and feed on the foliage.

Symptoms: The most obvious symptom of cutworm infestation is the disappearance of young seedlings overnight. You may also notice irregularly shaped holes in leaves and stems, as well as chewed roots.

Prevention and Control: To prevent cutworm infestation, keep the garden clean and free of debris. Cutworms usually hide under debris during the day. Till the soil in the fall to expose the pupae to predators. Use pheromone traps to monitor moth activity and prevent mating. You can also protect young seedlings by placing collars made of cardboard or paper around their stems.

If you already have a cutworm infestation, handpicking them from the soil is a great control measure. Apply Bacillus thuringiensis (Bt) insecticide to foliage, which is safe for humans but deadly for cutworms. Apply it late in the day when cutworms are active. Avoid applying insecticides during midday or when bees are active.

By taking preventative measures and quickly treating any signs of cutworm infestation, you can enjoy a healthy sweet potato harvest free from these pesky pests.

Sweet Potato Scab

Sweet potato scab is a common disease that affects sweet potatoes, causing raised, scabby lesions on the surface of the tubers. This disease is caused by a bacterium called Streptomyces ipomoeae, which can survive in soil for several years and infect sweet potato plants through wounds on the roots.

Symptoms of sweet potato scab include rough, scabby patches on the surface of the tubers, which may be tan, brown, or black in color. In severe cases, the lesions may be deep and cause the tubers to crack or become misshapen. While sweet potato scab does not affect the edibility of the tubers, it can reduce their market value and make them less attractive to consumers.

To control or prevent sweet potato scab, it is important to practice good sanitation in the garden. Remove and destroy any infected plant material and rotate crops to avoid planting sweet potatoes in the same location year after year. It is also recommended to choose disease-resistant varieties and to avoid planting sweet potatoes in soil with a pH above 6.0.

In conclusion, sweet potato scab is a common disease that can be controlled through proper sanitation practices and preventative measures. By taking steps to prevent this disease from infecting your sweet potato plants, you can ensure a healthy and bountiful harvest of delicious, nutritious sweet potatoes.

Fusarium Wilt

Fusarium Wilt is a fungal disease that can affect sweet potatoes and other plants. It is caused by the Fusarium oxysporum fungus, which attacks the plant's vascular system, leading to wilting and eventual death.

Symptoms: The first sign of Fusarium Wilt is the yellowing and wilting of the leaves, starting from the bottom of the plant and spreading upwards. The leaves may also become smaller and have brown or black streaks. The stems may also show discoloration and soft rot. Eventually, the entire plant will die.

Control or Prevention: The best way to prevent Fusarium Wilt is to use disease-free seedlings or cuttings. Crop rotation can also help, as the fungus can persist in the soil for several years. Avoid planting sweet potatoes in areas where other crops in the same family, such as tomatoes or peppers, have been grown recently. Fungicides may also help control the disease, but they are not always effective.

If Fusarium Wilt is detected, remove and destroy infected plants immediately to prevent further spread. Do not compost infected plants, as the fungus can survive in the soil. Clean tools and equipment thoroughly after use to prevent transmission of the disease to other plants.

Stem Rot

Stem rot is a common disease that affects sweet potatoes. It is caused by a fungus known as Fusarium solani which can survive in the soil for several years. Stem rot is more prevalent in wet conditions and can spread quickly through the soil.


The first sign of stem rot is wilting of the leaves, followed by a yellowing of the leaves and stems. The stem will become soft and mushy and will eventually collapse. Infected plants may also show signs of stunted growth and reduced yields.

Control or Prevention

Prevention is key when it comes to stem rot. It is important to plant sweet potatoes in well-draining soil that is not waterlogged. Avoid overwatering and make sure that the soil dries out between waterings. Crop rotation can also be helpful in preventing the spread of stem rot.

If you notice any signs of stem rot, remove the infected plants immediately to prevent the disease from spreading to healthy plants. You can also apply fungicides to protect healthy plants from infection.

In conclusion, stem rot can be a devastating disease for sweet potato growers. However, with proper prevention and management strategies, you can protect your crops and ensure a healthy harvest.

Root Knot Nematodes

Root Knot Nematodes are tiny, microscopic worms that can cause a great deal of damage to sweet potatoes. These pests feed on the roots of plants, causing the formation of galls or knots which can hinder the plant's ability to absorb water and nutrients.

Symptoms of Root Knot Nematodes include stunted growth, yellowing of leaves, wilting, and poor tuber development. If left unchecked, this pest can severely impact the yield of your sweet potato crop.

Prevention is key when it comes to Root Knot Nematodes. It is important to rotate your crops regularly to prevent the buildup of nematodes in the soil. Additionally, using resistant varieties of sweet potatoes can help prevent infestation.

If you suspect a Root Knot Nematode infestation, there are a few control methods available. Solarization, or covering the soil with clear plastic during hot weather, can help kill off nematodes in the soil. Fumigation with chemicals may also be effective, but should only be done by professionals. It is important to note that chemical control methods should be used as a last resort and always follow instructions carefully.

Southern Blight

Southern blight is a fungal disease that affects various plants, including sweet potatoes. The fungus responsible for this disease is Sclerotium rolfsii, which can survive in soil for years. This disease can cause significant yield loss and even plant death if not controlled in time.


The first visible symptom of southern blight is the appearance of water-soaked lesions on the stem near the soil line. The lesions quickly enlarge and become sunken and brown with white fungal growth. As the disease progresses, the stem becomes constricted and wilted, and the leaves turn yellow and die. Eventually, the entire plant collapses and dies.

Control or Prevention

Preventing southern blight starts with good cultural practices, such as planting in well-drained soil and avoiding excessive irrigation. Crop rotation and proper sanitation, such as removing infected plants and debris, can also help to prevent the disease. If southern blight has already infected the sweet potato crop, there are a few control measures that can be implemented, such as applying fungicides like azoxystrobin or boscalid to control the spread of the fungus. However, fungicide application should be done in conjunction with cultural practices for maximum effectiveness.

In conclusion, southern blight is a serious fungal disease that can have devastating effects on sweet potato crops. Early detection and proper control measures are crucial to preventing significant yield loss.

Author: Michael Chen
Bio: I'm gardening specialist with a mission to empower people to grow their own fruits and vegetables. With my background in Plant Science from the University of California and experience working with farmers and community gardens, I'm dedicated to promoting sustainable agriculture practices and helping individuals achieve bountiful harvests. Let's get growing!