Sweet potatoes are celebrated worldwide for their taste, nutrition, and versatility. Ranked as the seventh most important food crop globally, they thrive in tropical and subtropical regions, providing food, animal feed, and even biofuel.
In 2022 alone, U.S. farmers harvested more than 130,000 acres, generating nearly $600 million—mostly from the southeastern states that lead domestic production.
Despite their resilience, sweet potatoes face persistent threats below the surface. In regions like the southeastern United States, favorable soil and climate conditions also benefit the pests and pathogens that attack this vital crop.
In a recent Journal of Integrated Pest Management article, researchers highlighted key pests and the innovative strategies used to combat them.
Nematodes: The Invisible Saboteurs
Among the most destructive sweet potato enemies are root-knot nematodes—microscopic worms that infest roots, forming galls that disrupt water and nutrient uptake. The damage leads to stunted growth, reduced yields, and malformed storage roots.
Worse yet, nematodes often interact with other pathogens, compounding the harm and making control especially challenging for farmers.
These soil-dwelling parasites are difficult to detect until significant damage has occurred. Once established, nematodes can persist in soil for years, waiting for new crops to invade.
Their persistence highlights the importance of proactive management through resistant varieties, soil health practices, and ongoing monitoring.
Insect Pests Add to the Pressure
In addition to nematodes, several insect pests threaten sweet potato production. Chief among them is the sweetpotato weevil (Cylas formicarius), notorious for ruining storage roots and causing more than $7 million in annual losses across the southern United States.
Wireworms, cucumber beetles, and flea beetles further degrade root quality and reduce market value.
These insects not only cause direct feeding damage but also create entry points for pathogens. As a result, controlling them is essential to preserving both yield and root appearance—two critical factors for growers’ profitability.
Fighting Back with Resistant Varieties
Farmers’ first line of defense is smart variety selection. Modern cultivars such as ‘Covington’ and ‘Bonita’ show strong resistance to southern root-knot nematodes, outperforming traditional favorites like ‘Beauregard.’ Newer varieties like ‘Orleans’ offer high yields and strong performance under diverse field conditions.
However, no variety is entirely immune—especially against emerging pests like the guava root-knot nematode, a growing concern in U.S. fields.
This ongoing threat underscores the need for continued breeding programs that combine nematode resistance with other desirable traits such as yield, flavor, and adaptability.
Cultural and Biological Controls
Beyond genetics, farmers rely on cultural practices to keep pest populations in check. Crop rotation—especially with non-host crops like peanuts or bahiagrass—helps break pest life cycles. Good drainage and weed control further improve plant vigor and resistance.
Winter cover crops, such as mustard, enrich the soil and release compounds toxic to nematodes, though they must be managed carefully to avoid harboring insect pests.
Biological control adds another layer of defense. Beneficial fungi like Beauveria bassiana target insect pests, including weevils, while beneficial nematodes parasitize harmful insects such as wireworms.
Meanwhile, microbial nematicides like Purpureocillium lilacinum attack nematode eggs, helping reduce populations naturally. These eco-friendly tools support integrated pest management (IPM) systems that minimize chemical dependence.
Toward Sustainable Sweet Potato Farming
Despite major advances, researchers still face many unanswered questions. Biopesticides, cover crops, and resistant varieties show great promise but require continued testing to maximize their effectiveness.
The development of nematode-resistant cultivars capable of withstanding the guava root-knot nematode is especially urgent for protecting U.S. sweet potato production.
Sweet potatoes play an essential role in food security and economic stability worldwide. In the southeastern United States, they sustain both local economies and nutritious diets.
Through continued innovation in breeding, biological control, and cultural management, farmers and scientists can ensure this humble yet powerful crop continues to thrive against the odds.
FAQs
What are the main pests that affect sweet potatoes?
The biggest threats to sweet potatoes include root-knot nematodes, sweetpotato weevils, wireworms, cucumber beetles, and flea beetles. These pests attack the roots and stems, reducing yields and lowering crop quality.
How do root-knot nematodes damage sweet potatoes?
Root-knot nematodes feed on the plant’s root system, causing galls that block water and nutrient uptake. This leads to stunted growth, cracked or deformed roots, and reduced yields.
Which sweet potato varieties are resistant to nematodes?
Varieties such as ‘Covington’ and ‘Bonita’ have shown resistance to southern root-knot nematodes, while newer cultivars like ‘Orleans’ offer strong yield performance. However, no variety is fully resistant to the guava root-knot nematode, an emerging pest in the U.S.
What cultural practices help control sweet potato pests?
Crop rotation with non-host crops like peanuts or bahiagrass, improved field drainage, and weed control can reduce pest populations. Winter cover crops, such as mustard, also release natural compounds that suppress nematodes.
What biological controls are available for sweet potato pests?
Biological agents like the fungus Beauveria bassiana kill insect pests such as sweetpotato weevils. Beneficial nematodes and microbial nematicides like Purpureocillium lilacinum also help reduce harmful pest and nematode populations naturally.
