Abstract

Cassava is a crop of significant economic importance, with an export value exceeding 100 billion baht annually. Thailand ranks as the third-largest producer globally. However, the recent outbreak of cassava mosaic disease has caused a dramatic reduction in production, decreasing yields by 40-100%. This study aims to evaluate resistance to cassava mosaic disease in 71 F1 generated from crosses between the Huay Bong 80 and IITA-TMS-IBA980581 varieties. The experiment was designed using an Augmented in Randomized Complete Block Design to compare the performance of Huay Bong 80, Huay Bong 90, and IITA-TMS-IBA980581 varieties. Disease severity was assessed on a scale of 1 to 5, with data collected in the 3rd, 6th, and 9th months, and the crop was harvested at 10 months. The results indicated that at the 3rd month, 55 lines showed disease severity at level 1, 8 lines at level 2, and 8 lines at level 3. By the 6th month, 53 lines remained at severity level 1, with 18 lines at level 3. By the 9th month, 49 lines were still at severity level 1, and 22 lines were at level 3, with an average yield of 13.9 kilogram per plot.