Dragging a manure hose over corn at early growth stages does not reduce yield

Sidedressing corn (Zea mays L.) with liquid manure slurry via a manure hose application system was recently shown to be a viable practice to apply manure to a growing crop. However, little is known about what growth stage different corn hybrids can be dragged with a manure hose before plant population and grain yield is affected. A small-plot field study was conducted in 2019 and 2020 at both Saint Paul and Waseca in Minnesota to evaluate the effect of dragging a manure hose over corn on plant population, grain yield, and grain moisture of two hybrids with different mid-season brittle stalk ratings (Pioneer P0339R and P0306AM). Plots were dragged in both directions along the row with a manure hose from the first through sixth leaf collar growth stages (vegetative [V] growth stage V1 through V6) and compared to a non-dragged control. Plant population, grain yield, and grain moisture were generally not significantly affected by dragging corn between the V1 and V3 (third leaf collar) growth stages. Dragging at V4 reduced plant population and yield by 41% in 1 of 4 site-years, while dragging after V5 significantly reduced yield by 21-79% and in most cases, increased grain moisture. Yield did not differ between hybrids in any site-year except in Waseca 2019 when a July windstorm disproportionately affected hybrid P0306AM more than P0339R. These results suggest that when using a manure drag hose application system to sidedress corn, sidedressing should be completed before V4 to avoid damaging the crop, regardless of hybrid.