Affordable insect-proof net tunnels proved effective in reducing virus-related degeneration in sweetpotato in Tanzania. Re-infection in high virus pressure area was prevented for up to 20 months and 18 months for Polista and Kabode varieties, respectively. Seed degeneration modeling showed that virus buildup could lead to significant yield loss after 4 generations in the open field but would not be reached within 10 generations if seed was sourced from the protected structure and multiplied once before use (Fig. 1).