This study assessed the extant literature related to the use of high tunnels (HTs) in agricultural systems in the United States since the 2009 launch of the Natural Resources Conservation Service (NRCS) High Tunnel Initiative. This NRCS program led to an increase in HT adoption nationwide. The literature searches were conducted using the Web of Science (WoS) database. The final sample was 133 peer-reviewed articles published between 2009 and February 2023. We used CiteSpace 6.2.R1 and Gephi 0.9.2 to conduct co-citation, co-author, co-institution, and clustering techniques. The findings showed that the peer-reviewed literature about HT use has increased since 2009, substantially rising between 2017 and 2021. Horticulture was the top subject category in the literature, and most articles were published in peer-reviewed journals of the American Society for Horticultural Science (i.e., HortTechnology and HortScience). The research field evolved from general HT practices, nutrient management, and plant pathology to focus on trials of specific crops and integrated pest management. The institutions with the most contributions to the HT literature were Kansas State University, the University of Florida, Michigan State University, Purdue University, and the University of Minnesota. The patterns of HT research revealed in this study offer a greater understanding of the current state of knowledge to inform the focus of future research.

Field studies were conducted at three locations during both 2002 and 2003 to evaluate weed control and response of glyphosate-resistant (GR) corn to glyphosate or nicosulfuron plus atrazine applied POST at three application timings with and without alachlor plus atrazine applied PRE. The POST herbicides were applied timely (5- to 9-cm weeds) or applications were delayed 1 or 2 wk. All treatments, except the weedy check, were followed by glyphosate postemergence-directed (PDIR) 4 wk after the timely POST application. Common lambsquarters, common ragweed, Palmer amaranth, prickly sida, and smooth pigweed were controlled at least 94% regardless of PRE or POST treatments. Large crabgrass and fall panicum were controlled at least 96% by glyphosate regardless of PRE herbicide or POST application timing. In contrast, control by nicosulfuron plus atrazine POST in the absence of PRE herbicide decreased as application was delayed. Sicklepod was controlled at least 94% when POST herbicides were applied timely, but control by both POST herbicide treatments decreased with delayed application regardless of PRE herbicide. Tall morningglory was controlled 93% or greater by POST herbicides applied timely. Control by both POST herbicide treatments decreased as application was delayed, with glyphosate being affected more by timing than nicosulfuron plus atrazine. Corn grain yield was similar with glyphosate and nicosulfuron plus atrazine. Yield was unaffected by POST application timing when PRE herbicides were included. Without PRE herbicide, grain yield decreased as POST herbicide application was delayed.