Sweet Potato Pox: A Serious Disease Affecting Sweet Potato Crops
What is Sweet Potato Pox?
Sweet potato pox is a devastating disease that can cause significant economic losses to farmers and negatively impact the global sweet potato production. It is caused by a soil-borne pathogen called Streptomyces ipomoea and is commonly known as soil rot. The disease affects the roots of sweet potato plants, leading to the development of black necrotic lesions, distortion, and dents. Infected tubers become inedible, and in severe cases, the entire plant may die.
Symptoms of Sweet Potato Pox
The symptoms of sweet potato pox can vary depending on the stage of infection. Above ground, infected plants may exhibit yellowing and wilting of leaves. In extreme cases, the plants may even die or fail to produce tubers. The tubers themselves develop distinct black crusty lesions, become distorted, and have dents in places. The fibrous feeder roots will rot at the ends, interrupting plant uptake. The underground stems will also blacken and turn soft.
Conditions that Promote Sweet Potato Pox
The development of sweet potato pox is influenced by several factors, including soil pH, soil type, and the presence of weeds in the morning glory family. The pathogen survives for years in soil and can also infect weeds, serving as a reservoir for the disease. Grassy, light, dry soils with a pH above 5.2 create favorable conditions for the pathogen to thrive. Contaminated equipment, infected tubers used as transplants, and even stored sweet potatoes can contribute to the spread of the disease.
Preventing Sweet Potato Pox
Implementing good sanitation practices is crucial for preventing the spread of sweet potato pox. Decontaminate all hand and mechanical tools before moving into another field. Even soil or storage boxes can harbor the disease, so it is essential to thoroughly clean and disinfect them. Crop rotation can help prevent the movement of the pathogen, as can fumigating soil. Planting resistant varieties of sweet potato is one of the most effective methods of control. Some resistant varieties include Covington, Hernandez, and Carolina Bunch.
Management of Sweet Potato Pox
Managing sweet potato pox requires a combination of cultural practices and chemical control measures. Sanitation practices, such as crop rotation and the use of clean planting materials, can reduce the risk of infection. Adjusting soil pH to below 5.2 can also help suppress the pathogen. In cases of severe infection, fungicides may be necessary to control the disease. However, it is important to note that chemical control should be used as a last resort, as excessive use can lead to the development of resistant strains of the pathogen.
Long-Term Impact of Sweet Potato Pox
Sweet potato pox can have significant long-term impacts on sweet potato production. Infected fields may become unusable for growing sweet potatoes for many years, leading to reduced yields and economic losses. The disease can also affect the quality of tubers, making them unmarketable. In severe cases, sweet potato pox can lead to the collapse of entire crop production systems, especially in areas where sweet potatoes are a staple food.
Conclusion
Sweet potato pox is a serious disease that can have devastating consequences for sweet potato crops. Understanding the causes, symptoms, and management strategies for sweet potato pox is crucial for farmers and agricultural professionals to protect their crops and ensure a sustainable sweet potato production system.