Field trials were conducted in 2016 and 2017 at the Southwest Purdue Agricultural Center in Vincennes, IN, to determine the tolerance of plasticulture-grown ‘Fascination’ triploid watermelon to flumioxazin. Treatments were applied after plastic was laid, but 1 d prior to transplanting, and consisted of row middle applications of clomazone (210 g ai ha^–1) plus ethafluralin (672 g ai ha^–1), flumioxazin (107 g ai ha^–1), and flumioxazin (88 g ha^–1) plus pyroxasulfone (112 g ai ha^–1); a broadcast application of flumioxazin (107 g ha^–1); and a nontreated check. The broadcast application of flumioxazin reduced watermelon vine length and normalized difference vegetation index (NDVI) values compared with values for the nontreated check. All other herbicide treatments had vine length and NDVI values similar to those of the nontreated check. At 25/26 d after transplanting (DAP), weedy ground cover in row middles of the nontreated check was 39% and 14% in 2016 and 2017, respectively. Weedy ground cover in herbicide-containing treatments was significantly less, at ≤7% and ≤5% in 2016 and 2017, respectively. Marketable watermelon yield of the nontreated check was 77,931 kg and 11,115 fruits ha^–1. The broadcast application of flumioxazin resulted in reduced marketable yield (64,894 kg ha^–1) and fewer fruit (9,550 ha^–1).

Nomenclature: Clomazone; ethalfluralin; flumioxazin; pyroxasulfone; watermelon ‘Fascination’; Citrullus lanatus (Thunb.) Matsum. & Nakai