Abstract
Background and Objective: Papaya ringspot virus (PRSV) is a major constraint on commercial papaya (Carica papaya L.) production. This study evaluated chemical-free indigenous barrier cropping systems to suppress PRSV incidence and severity while optimizing fruit yield for smallholders in Thailand.Methodology: A field experiment using a randomized complete block design with five treatments and five replications was conducted in Maha Sarakham province. Papaya plots (2.5 m × 2.0 m spacing) were surrounded by double-row living barriers of different companion crops positioned 3.0 m away. Evaluated treatments included papaya bounded by: (1) banana (Musa ABB group), (2) custard apple (Annona squamosa L.), (3) cassava (Manihot esculenta), (4) sugarcane (Saccharum officinarum), and (5) a monoculture control. Yield, fruit quality, total soluble solids (°Brix), PRSV incidence (%), and severity scores (0–4 scale) were monitored. Mean separation was performed using Duncan's multiple range test (P < 0.05).Main Results: Integrated barriers significantly mitigated viral impacts and enhanced yields compared to the control (P < 0.05). The control exhibited maximal disease pressure, recording 100.00 ± 0.00% incidence and a 3.92 ± 0.11 severity score. Sugarcane and custard apple barriers minimized incidence to 61.04 ± 6.90% and 53.12 ± 7.20%, and severity to 2.37 ± 0.28 and 2.44 ± 0.25, respectively. The banana boundary system demonstrated the highest agronomic performance despite an 88.61 ± 9.45% incidence and 3.15 ± 0.38 severity score. It produced the highest fruit count (130.62 ± 18.45 fruits/tree), mean weight (2.30 ± 0.35 kg), flesh thickness (3.40 ± 0.42 cm), and peak sweetness (16.00 ± 1.50 °Brix) over the control.Conclusions: Diversified polyculture provides a viable non-chemical strategy for PRSV suppression. Sugarcane and custard apple systems likely serve as physical/visual vector barriers. Meanwhile, the banana model potentially provides agroecological modifications supporting crop vigor under disease pressure.