S14 - Session O4 - Use of row cover on yellow squash and zucchini production to manage whitefly and whitefly-transmitted viruses

Authors: Andre da Silva *, Timothy Coolong, Ayanava Majundar, Edward Sikora, Alvin Simmons

Growing seasons of agronomic and vegetable crops are commonly overlapped in the southeastern US, which associated with subtropical characteristics of the region, create optimum environmental conditions for whitefly ( Bemisia tabaci ) and whitefly-transmitted viruses (i.e., Cucurbit leaf crumple virus (CuLCrV)) to cause reductions in yield of cucurbit crops (i.e., yellow squash and zucchini). Growers rely on heavy insecticide spraying programs to control the insect and disease pressure, but these are costly and not sustainable strategies. The objective of this study was to evaluate the efficacy of row cover strategies for the management of whitefly and CuLCrV on yellow squash and zucchini production. Field experiments were conducted in 2019 and 2020 in Georgia, US, and 2021 in Alabama, US. Experiments were randomized in a complete block design (r=4), using row cover strategies as treatments. Row cover strategies consisted of small tunnels of mesh net kept from transplanting to flowering and a non-cover treatment using growers' standard spraying program. During growing seasons, the number of whiteflies was consistently higher in non-covered compared to covered areas until the removal of covers. Whitefly population was weekly measured and peaked at 211, 122, and 149 whiteflies/trap for non-cover treatment in 2019, 2020, and 2021, respectively. Row cover areas had no whitefly in the same period. After removing row covers, whitefly population had no significant differences among treatments. Overall, row covers had 62% lower incidence of CuLCrV than rows non-covered, which impacted crop development and yield. Across the three years studied, yellow squash and zucchini yields were on average 12% and 8% higher for covered than non-covered treatments, respectively. In general, the use of row cover performed the best and demonstrate potential to substitute the heavy spraying program during the whitefly season in southeastern US; however, an economic analysis is still required to guide growers in decision-making.