A survey was carried out in Paraguay to investigate the prevalence and distribution of sweet potato virus diseases. Two DNA viruses, Sweet potato pakakuy virus (SPPV) and Sweet potato symptomless virus (SPSMV), and three RNA viruses, Sweet potato feathery mottle virus (SPFMV), Sweet potato virus G (SPVG), and Sweet potato virus C (SPVC), were detected. They were cloned and sequenced. Sequences were deposited in GenBank of the National Center for Biotechnology Information. Of 53 samples from which viruses were detected, SPVG was detected in 29, representing 57.6% of virus-detected samples. The second most common virus was SPFMV. It was detected in 23 samples. This is the first report of a sweet potato virus disease outbreak in Paraguay confirmed through viral sequence analysis.

Within the framework of a project entitled “Development of Advanced Sweet Potato Cultivation Technology for Smallholder Farmers in Paraguay” implemented by KOPIA Paraguay Center (Korea Partnership for Innovation of Agriculture) in collaboration with Paraguayan Institute of Agricultural T echnology (I PTA) d uring the period 2021-2024, r esults o f four m ain e xperiments are described in this research: selection of suitable varieties, optimal planting and harvesting times, the use of ridges, and optimal chemical fertilization doses. In the selection of suitable varieties for Paraguay, 11 sweet potato varieties were evaluated in departments of San Pedro and Misiones. As a result, varieties Andaí, Jety Paraguay, and Chaco I showed the highest productivity in San Pedro, while varieties Jety Uruguayo, Chaco I, and Taiwanés showed higher productivity in Misiones. The other three experiments were carried out in San Pedro only. Optimal planting and harvesting times were determined with three varieties: Andaí, Pyta Guasu, and Jety Paraguay. For Andaí and Jety Paraguay varieties, they should be planted in December and harvested at 122 days post planting (DPP). For Pyta Guasu, it should be planted in October and harvested at 124 DPP. Regarding productivity response with soil preparation methods, the use of ridges showed higher yields in all planting methods, with the curved method planting being the most productive. Finally, optimal chemical fertilization doses were established in order to improve the total yield. The optimal nitrogen fertilizer dose (urea 45% N) was 40 kg/ha. The optimal phosphorus fertilizer dose (triple superphosphate 45% P2O5) was 80 kg/ha and the optimal potassium fertilizer dose (potassium chloride 60% K2O) was 120 kg/ha.