A field study was conducted in 2002 and 2003 to evaluate tolerance of eight rice cultivars to clomazone at 896 g ai/ha impregnated onto urea fertilizer. Rice foliar bleaching was 16 to 20% at 14 d after rice rooting (DAR) for long-grain cultivars ‘Ahrent’, ‘Cheniere’, ‘Cocodrie’, ‘Cypress’, ‘Francis’, and ‘Wells’ and 23 and 30% for medium-grain ‘Bengal’ and short-grain ‘Pirogue’, respectively, when clomazone was impregnated onto urea. Clomazone reduced the number of tillers/ m2 21 DAR for all cultivars. Early season height reductions occurred for all cultivars; however, Pirogue was the only cultivar shorter than the nontreated at harvest. There were no yield reductions with regard to the medium and long-grain cultivars when compared with respective nontreated cultivars. However, yield of short-grain Pirogue treated with clomazone was 1,740 kg/ha less than the nontreated.

Rhizoma peanut (Arachis glabrata Benth.) is one of the few high‐quality legume forages that will persist in Florida. Rhizoma peanut hay is valued by horse and cattle producers, but weeds reduce its quality and value. Herbicides are often required for weed control, but it is not known which herbicides can be applied without causing injury and yield loss. Herbicides were applied to the rhizoma peanut cultivars ‘Florigraze’ and ‘Arbrook’ in 2004 and 2005 at 3 or 21 days after clipping (DAC). Dicamba + 2,4‐D was highly injurious at both application timings, while hexazinone was most injurious when applied at 21 DAC for both cultivars. However, no herbicide applied at 3 DAC resulted in yield loss for either cultivar. When applied at 21 DAC, dicamba + 2,4‐D reduced yield by 41 and 22% of Florigraze and Arbrook cultivars, respectively compared to the non‐treated control. Similarly, hexazinone (0.28 and 0.56 kg/ha) reduced yield of Florigraze and Arbrook cultivars by at least 50 and 36%, respectively, compared to the non‐treated control. Applications of 2,4‐D alone reduced Florigraze yield by 41% compared to the non‐treated control, but Arbrook yield was not affected by this herbicide. Florigraze appeared to be more sensitive to all herbicides with regard to visual injury and forage yield. Applications of imazapic, imazamox, and 2,4‐DB did not result in visual injury or yield loss at either application timing for either cultivar.

Foliar delivery of herbicides is a common means for plant management in aquatic environments. Though this technique is decades old, little is known about vegetative spray retention relative to this application method. A more complete understanding of maximizing herbicide retention could lead to improved plant management while simultaneously decreasing pesticide load in aquatic environments. Therefore, outdoor mesocosm experiments were conducted in 2020 to evaluate the effect of adjuvant type on foliar spray retention in waterhyacinth. Additionally, the effect of carrier volume on spray retention in waterhyacinth, waterlettuce, and giant salvinia was documented. Spray deposition did not differ among the nine adjuvants tested; however, spray retention was reduced 6 to 11% when an adjuvant was excluded from the spray solution. The effect of carrier volume on spray retention in waterhyacinth, waterlettuce, and giant salvinia was also investigated. Decreases in spray retention was most sensitive to increased carrier volume in waterhyacinth, followed by giant salvinia and waterlettuce. Among species, spray retention potential, as determined by intercept estimates, was greatest in waterlettuce and giant salvinia regardless of carrier volume. Asymptotes estimates for waterhyacinth, waterlettuce, and giant salvinia were 33, 46, and 79% spray retention, respectively. In other words, spray retention was the lowest and remained relatively constant at these values for the high carrier volumes tested (935 and 1870 L ha−1), which were likely due to the presence of pubescence on leaves and flatter leaf architecture represented by waterlettuce and giant salvinia compared to the glabrous vertical leaves of waterhyacinth. Future research will evaluate these concepts under field conditions.

Immense stands of bald cypress [Taxodium distichum (L.) Rich.] make it difficult for herbicide applicators to access the free-floating fern giant salvinia (Salvinia molesta Mitchell), which can be found growing under the canopy of the trees. The difficulty of accessing these areas, as well as avoiding direct contact of herbicides with tree foliage, provides a substantial amount of nonmanaged plant material capable of rapidly reinfesting treated sites, thus making management efforts null and void. Herbicide application during the winter, when bald cypress sheds its leaves, may be an ideal time to manage S. molesta and minimize negative impacts on the nontarget tree. Therefore, the herbicides diquat, glyphosate, flumioxazin, and glyphosate+diquat were evaluated at one of the three application timings (December, January, or February) against S. molesta and immature bald cypress during the winter. All herbicide treatments, except diquat applied in February of year 1, reduced S. molesta biomass 40% to 100%. In addition, flumioxazin applications during December, January, and February provided ≥70% S. molesta control with little or no negative impacts to bald cypress health. A treatment by timing interaction revealed that trees exposed to flumioxazin did not result in a significant decrease in average leaf length when compared with reference trees 20 wk after bud break at any of the three application timings. In addition, bald cypress exposed to flumioxazin produced the highest probability of a refoliation pattern equivalent to the nontreated reference trees. Although complete tree mortality was not documented in either study, delayed and abnormal leaf formation, reduced leaf length, irregular canopy formation, or no negative effects were observed among herbicide-treated bald cypress. This research suggests that winter herbicide applications over the top of dormant bald cypress may be a practical management technique for controlling severe infestations of S. molesta.