Field studies were conducted twice at two sites in St. Croix, United States Virgin Islands, to determine the effectiveness of preemergence applications of bensulide and halosulfuron in transplanted watermelon. Bensulide and halosulfuron were both applied separately. Although bensulide caused up to 5% seedling stunting and halosulfuron caused up to 10% seedling stunting and discoloration, watermelon plants were fully recovered by week 8 after planting. Yields of all treatments were similar to that of untreated plots. Control of grasses like goosegrass and of broadleaf weeds like amaranthus was not found in treated plots. Weed species, weed densities and the percentage of weed control found in bensulide and halosulfuron treated plots were similar to non-treated plots. Watermelon fruits in both treated and non-treated plots had a degree of brix of 8.5, which indicates poor quality fruits.