Sweet Potato Major Pests, Diseases and Weed Control

Sweet Potato Weeds, Pests and Diseases
Sweet Potato


Editorial team

Share it:

Sweet potatoes are generally susceptible to more than 40 diseases (+20 viruses) and 40 species of pests globally. However, the type and severity of an enemy that a sweet potato farmer may need to confront highly depend on the region, the year, and the cultivation practices applied on the field. 

Sweet Potato Common Pests

Sweet potato weevil

Sweet potato weevil (Cylas spp. or Cylas formicarius, or Euscepes postfasciatus) is a small, looking like an ant beetle that is considered the most dangerous and destructive enemy of sweet potatoes, costing extensive yield losses globally and especially in tropical and subtropical areas. If left uncontrolled can lead to up to 60-95% plant loss. The pest that originated in America attacks the storage roots, by creating tunnels on the roots, both in the field and during storing. The infested and damaged sweet potatoes become spongy and black and have an unpleasant terpene odor and a bitter taste. The larvae cause the most severe problems in the roots, but damage can also be caused in the vines (in earlier developmental stages). The attack is difficult to be detected as the damage is done underground. These injuries can also serve as entries for soil-borne pathogens. Thus, most of the time, it is overlooked until potatoes are harvested.

To control the pests and protect their crops, sweet potato farmers focus on field sanitation by removing crop residues and plowing after the harvest. This aims to remove unharvested infested roots and expose the pest to natural enemies. Elimination of Ipomea weeds, application of measures to avoid soil cracking (entering points), and using suitable, healthy planting material are essential management practices. It is essential to remove the infested plants, and when the problem is severe, many farmers choose to apply suitable insecticides. Finally, the storage equipment and area must be cleaned and fumigated. 

Sweet potato Flea Beetle

Chaetocnema confinis originated in North America. However, several sweet potato flea beetles have spread rapidly worldwide. Adults attack plants (especially seedlings), causing irregular whitish marks and holes (‘shot hole’ appearance) on the upper surface of foliage as they feed on the top of the leaves. The damage by the adults is usually extended to the whole leaf canopy. On the other hand, the larvae feed on the roots by trimming the root hair and making circular pita in tap roots. In heavy infestations, sweet potatoes lose their marketable value. 

Once the cultivation has been attacked, management is more difficult. That is why farmers usually invest in integrated pest management practices. The use of row covers after placing the seedlings on the field has been proven effective in keeping the insects away. Sticky traps (white or yellow) can be placed in the rows (5-10 m apart). Finally, it is essential to rotate crops and avoid planting sweet potatoes yearly on the same field since the insect can easily build up threatening (large) populations. 

Other important pests that can damage the crop are: nematodes, wireworms, white grubs, cucumber beetles, aphids, thrips, and whiteflies. 

Sweet Potato Major Diseases

Black rot

It is caused by the soil-borne fungus Ceratocystis fimbriata and is one of the most common sweet potato diseases. It is characterized by dark sunken, darkish spots on the roots and the lower parts of the stem. The fungus can be transmitted with infected propagation material (slips), while it can also enter the plants through the wounds caused by pests. 

The fungus can survive up to 2 years in the field in crop residues. As a result, in case suspicious symptoms are observed, the infected plants should be removed from the field (during cultivation and after harvest). To control the disease, the farmers should use only healthy, certified slips. In the case the slips are produced on the farm, it is important to avoid taking cuttings from diseased plants. In areas with known disease history, the grower can treat the seed roots with a suitable fungicide before planting and apply a 2-3 year crop rotation with non-host crop species. In general, avoiding cultivating sweet potatoes in soil with poor drainage or waterlogging is vital since such conditions can increase the damage. 

Alternariosis, Anthracnose, or Blight

The Alternaria spp or Alternaria bataticola fungi are responsible for the disease, causing significant problems in Latin America, Africa, and the Mediterranean. The fungus overwinters on crop debris, seeds, or weeds and is favored by high relative humidity and rain and spread by air and water. Symptoms include brown, necrotic lesions appearing on older leaves (petioles and stems), with characteristic concentric rings resembling the bull’s eye. In severe infections, sweet potato vines may die. 

Disease control begins with proper precautionary measures. These include weed control and safe distances between plants for better aeration (reduced humidity) and irrigation methods that do not wet the foliage. The general condition of the plants (nutrients and water level, sun exposure) can also boost their immunity. The grower should avoid using very susceptible varieties and always use healthy slips. Chemical treatment is used only if the problem is severe and always under supervision from a local licensed agronomist. It is also crucial to use proper sanitation, such as tools disinfection every time we touch the plants.

Fusarium Wilt/Fusarium Surface Rot and Fusarium Root Rot

Fungi of the genus Fusarium are responsible for the disease in sweet potatoes. More specifically, the species Fusarium solani (F. solani f. sp. batatas) cause the Root Rot, while the Fusarium oxysporum f. sp. batatas are responsible for the Fusarium wilt.

Generally, it is tough to distinguish the 2 diseases only by observing the symptoms. Common symptoms are circular lesions with light or dark-brown concentric rings. The root rot can reach the central parenchyma of the root (while the fusarium wilt cannot), causing open cavities. The lesions are gradually becoming larger, dry, spongy, and sunken, while they might be covered with white mycelia. 

Usually, the control measures for the Fusarium wilt can also work for the fusarium root rot. In both cases, it is essential to use disease-free propagation material. Use of resistant varieties like ‘Sumor’ and ‘Vardaman’ should be selected in fields with known Fusarium wilt disease history. The pathogen can survive in the soil for up to 5 years. As a result, it is essential to apply crop rotation (5 or more years) with non-host species. The grower should properly sanitize the equipment used, avoid damaging the roots and apply proper curing of the sweet potatoes soon after harvest. It is essential to efficiently control nematodes and insects that can damage the roots, creating entry points for the pathogen. 

Weed Management in Sweet Potato

Sweet potatoes have extensive cultivation season, and the weed pressure, especially in the early developmental stages of the crop, can lead to up to 90% yield loss and decreased quality. Weeds can compete with sweet potato plants for light, space, water, and nutrients, while they can be hosts of major crop pests and diseases and make harvesting the roots more difficult. As a result, the sweet potato farmer should invest in a suitable integrated weed management program. 

The farmer can start by identifying the weeds growing on his/her field (species, population size, etc.) and obtain information concerning their physiology (life cycle, reproduction rate, etc.). Usually, perennial weed species are the biggest problem for sweet potato growers. The weed species may vary depending on the environment, the crop history, and the (weed) management practices used. Some common weeds found in sweet potato fields are the:

  • Cyperus esculentus, common name: Yellow Nutsedge
  • Palmer amaranth or Amaranthus palmeri, common name: carelessweed
  • Convolvulus arvensis, common name: bindweed or morning glory
  • Digitaria sanguinalis, common name: Large crabgrass or Hairy crabgrass    
  • Richardia scabra, common name: Florida pusley or rough Mexican clover
  • Cyperus difformis, common name: Smallflower umbrella sedge
  • Elymus repens, common name: Quackgrass or Couch grass, 
  • Stachys palustris, common name: Marsh hedge-nettle or Marsh woundwort

To avoid significant yield losses due to weed competition, the farmer should keep his/her field weed-free for the first 30-45 after transplanting the slips (critical period). After this period, the sweet potato plants develop enough canopy mass (vines) to suppress the newly growing weeds effectively. However, before canopy covering, the farmer must combine pre- and post-planting measures to control the weeds. These can be cultural and mechanical practices and herbicide applications.

The cultural weed control methods mainly focus on controlling the weeds through:

  • crop rotation, 
  • use of cover crops and residue management (no-tillage practices), 
  • Machinery sanitation to avoid contamination (entry of weed seeds on the field), 
  • use of weed-free propagation material, 
  • use of allelopathic sweet potato varieties, 
  • mulching, (When plastic mulching is being used, the growers should be very careful, especially in the warmest areas, to avoid increasing soil temperature too much and stress the crop. The plastic is usually removed after the critical period.) 

For mechanical weed control, many sweet potato farmers use tractor-drawn cultivators and hand hoeing. After transplanting, disc hillers, rolling cultivators, and hand weeding should be preferred to minimize soil disturbance and damage to the crop roots. 

Finally, the farmer should be cautious when selecting herbicides. Organic farmers should only use products certified for organic agriculture. In all cases, it is essential to respect the time of the application, the dosage mentioned in the product label, and frequently changing modes of action to avoid weed resistance. Products with alachlor, metolachlor, and metribuzin have effectively controlled some of the most common sweet potato weeds. Pre-emergence herbicides should be applied before the planting of the crop, while the post-emergence ones should be applied by respecting the minimum days from harvest (mentioned on the label). You can use selective herbicides after planting the crop to avoid toxicities. Numerous options are available, but all farmers should consult their local licensed agronomist to find the most suitable (and registered) product. 


Glaze, N., & Hall, M. (1990). Cultivation and Herbicides for Weed Control in Sweet Potato (Ipomoea batatas). Weed Technology, 4(3), 518-523. doi:10.1017/S0890037X00025896

Sweet Potato cultivation guide:

Fast Facts about Sweet Potatoes

Sweet Potato Plant Information and Variety Selection

Sweet Potato Nutrition and Health Benefits

How to Grow Sweet Potatoes in Your Backyard

How to Grow Sweet Potatoes for Profit

How to Produce Sweet Potato Slips

Sweet Potato Soil Requirements, Soil Preparation, and Planting

Sweet Potato Water Requirements and Irrigation Systems

Sweet Potato Fertilization Requirements

Sweet Potato Major Pests, Diseases and Weed Control

Sweet Potato Yield, Harvest, Curing, and Storage

Sweet Potato in Bulk Wholesale Prices


We join forces with N.G.O.s, Universities, and other organizations globally to fulfill our common mission on sustainability and human welfare.