Molecular Pathogens, 2025, Vol.16, No.3, 87-99 http://microbescipublisher.com/index.php/mp 93 4.2 Traditional and molecular diagnosis methods There are two main ways to diagnose root rot in sweet potatoes: traditional methods and modern molecular methods. Traditional diagnosis looks at the symptoms and tries to grow the fungus from the sick plants. Trained plant doctors can tell from the wilting leaves and root rot whether the plant has root rot, and guess whether it’s caused by F. oxysporum or F. solani (Lee et al., 2019). To confirm, they take a piece of root from the edge between sick and healthy areas, clean it, and put it on a special growing plate. Komada medium is often used for this-it helps grow Fusarium while stopping other fungi. Under a microscope, they check the shape and color of the spores and compare with known types. While these methods work, they are slow and need clean lab conditions. So, many labs now use molecular tools to speed things up. PCR (Polymerase Chain Reaction) is the most common method. It finds small pieces of fungal DNA in just a few hours. Scientists have made special primers that detect F. oxysporum f. sp. batatas (the type that attacks sweet potatoes). There are also PCR kits that can detect several root rot fungi in one go and even measure how much fungal DNA is present in the soil or plant. This helps to estimate how serious the disease risk is (Wei et al., 2019). Besides PCR, antibody-based tests are also used. These use test strips or ELISA kits that react if Fusarium is present in root juice samples. Though mostly used for major crops, they can help identify sweet potato infections too. For complicated samples, DNA sequencing is now used. This method reads all the DNA in the sample, telling us exactly which fungi are present-even rare or unknown ones. This is helpful when the traditional method misses something. In short, traditional and molecular tools work best together. Growing the fungus in a lab is still the gold standard for identifying what it is. But PCR and sequencing make it easier to test many samples quickly. Together, they make diagnosing sweet potato root rot faster and more accurate. 5 Integrated Control Strategies 5.1 Variety selection and breeding Choosing healthy sweet potato roots and growing resistant varieties are basic and long-term ways to control root rot. First, farmers should use only clean, virus-free planting materials. Any root with dark spots or leaking black liquid should not be used. During seedling production, using sterile soil or disinfected nursery beds can help reduce harmful fungi in the soil. When cutting sweet potato vines for planting, it’s better to cut them 2 cm~3 cm above the soil instead of pulling out the whole root, to avoid spreading soil-borne disease. In places with good conditions, water-floating or greenhouse tray methods can be used to grow seedlings and stop Fusarium from spreading through soil (Bodah, 2017). For farmers who keep seeds from their own fields, it's important to check fields often, remove sick plants quickly, and burn or bury them far from the field. This helps stop the disease from returning the next year. Also, breeding and using resistant varieties is a key step. Although no sweet potato variety is completely immune to root rot, many new lines show better resistance. Researchers in several countries have made progress in developing new types that are both productive and more tolerant to disease. In China, some new varieties show much lower infection rates than old ones. With better genetic tools, like marker-assisted selection, it may become faster to breed varieties resistant to root rot. For example, Kim et al. (2023) found new genes linked to F. solani resistance, which could help future breeding efforts. 5.2 Field management and crop rotation Good farming practices are very important to reduce root rot in the field. First, field conditions should be improved to stop the fungus from infecting plants. Sweet potato should be planted in sunny, well-drained sandy soil. Avoid planting in wet lowland areas, which makes it easy for disease to start. Planting on high ridges and using plastic mulch can help keep the plant base dry and reduce disease. Also, sweet potato should not be planted in the same field year after year. Rotating with crops like rice, corn, or soybean for 2~3 years can help reduce harmful fungi in the soil. In fields with serious disease, rotation is the best way to kill Fusarium and bring back healthy soil microbes.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==