Response of Corn and Palmer amaranth to Mesotrione

Mesotrione is a herbicide used for the selective pre- and post-emergence control of a wide range of broadleaf and grass weeds in corn (Zea mays). It inhibits the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD) which leads to stop biosynthesis of plastoquinone, a key factor in the synthesis of carotenoid pigment. The depletion of carotenoids leading to bleaching symptoms followed by necrosis in sensitive plants. Palmer amaranth (Amaranth Palmeri) is one of the major weeds in corn production system. This study was conducted to test the hypothesis that mesotrione may be effective to control Palmer amaranth and safe for use in corn. Therefore, the objective of this research was to evaluate response of corn and Palmer amaranth to mesotrione. Corn and Palmer amaranth plants were treated with mesotrione at 105 g ai ha-1,and plant survival data was collected at 3 week after application. There was no injury reported to any of the corn plant, and plant survival rate was reported 100%. However, Palmer amaranth plants showed bleaching symptoms followed by necrosis and plant death. Only 12.5% Palmer amaranth plants survived after mesotrione application. These results demonstrated the tolerance of corn and sensitivity of Palmer amaranth to mesotrione

Differential sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides

Panicum schinzii (Transvaal millet), P. dichotomiflorum (Fall panicum) and P. capillare (Witchgrass) are alien panicoid grasses that have gradually spread and are now locally naturalized in corn fields in Belgium. One of the possible reasons for their expansion in corn fields might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HP-PD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two AILS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling populations of P. schinzii, P. dichotomiflorum and P. capillare (all naturalized Belgian populations except for P. capillare). In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive to tembotrione but moderately sensitive to topramezone and poorly sensitive to mesotrione and sulcotrione. However, P. dichotomiflorum was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized P. dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage)

Changes in Endogenous Carotenoid Pools of Turf and Weed Species as Affected by Mesotrione and Environmental Conditions

Mesotrione, a carotenoid biosynthesis inhibiting herbicide, was evaluated for its use in turfgrass systems. Experiments were conducted to evaluate smooth crabgrass (Digitaria ischaemum) control with preemergence applications of mesotrione plus prodiamine. Experiments evaluated the influence of application timing on the efficacy of mesotrione plus prodiamine combinations and compared mesotrione plus prodiamine to current preemergence and early-postemergence herbicide treatments used for control of crabgrass. Greenhouse studies were conducted to compare the effects of foliar, soil, and soil plus foliar application of mesotrione on yellow nutsedge (Cyperus esculentus) and large crabgrass (Digitaria sanguinalis). Research was conducted in environmental growth rooms to investigate the effects of light intensity and temperature on perennial ryegrass (Lolium perenne) and large crabgrass carotenoid composition following mesotrione application

Physiological and Molecular Characterization of Hydroxyphenylpyruvate Dioxygenase (HPPD)-inhibitor Resistance in Palmer Amaranth (Amaranthus palmeri S. Wats.)

Citation: Nakka, S., Godar, A. S., Wani, P. S., Thompson, C. R., Peterson, D. E., Roelofs, J., & Jugulam, M. (2017). Physiological and Molecular Characterization of Hydroxyphenylpyruvate Dioxygenase (HPPD)-inhibitor Resistance in Palmer Amaranth (Amaranthus palmeri S. Wats.). Frontiers in Plant Science, 8, 12. doi:10.3389/fpls.2017.00555Herbicides that inhibit hydroxyphenylpyruvate dioxygenase (HPPD) such as mesotrione are widely used to control a broad spectrum of weeds in agriculture. Amaranthus palmeri is an economically troublesome weed throughout the United States. The first case of evolution of resistance to HPPD-inhibiting herbicides in A. palmeri was documented in Kansas (KS) and later in Nebraska (NE). The objective of this study was to investigate the mechansim of HPPD-inhibitor (mesotrione) resistance in A. palmeri. Dose response analysis revealed that this population (KSR) was 10-18 times more resistant than their sensitive counterparts (MSS or KSS). Absorbtion and translocation analysis of [C-14] mesotrione suggested that these mechanisms were not involved in the resistance in A. palmeri. Importantly, mesotrione (>90%) was detoxified markedly faster in the resistant populations (KSR and NER), within 24 hours after treatment (HAT) compared to sensitive plants (MSS, KSS, or NER). However, at 48 HAT all populations metabolized the mesotrione, suggesting additional factors may contribute to this resistance. Further evaluation of mesotrione-resistant A. palmeri did not reveal any specific resistance-conferring mutations nor amplification of HPPD gene, the molecular target of mesotrione. However, the resistant populations showed 4- to 12-fold increase in HPPD gene expression. This increase in HPPD transcript levels was accompanied by increased HPPD protein expression. The significant aspects of this research include: the mesotrione resistance in A. palmeri is conferred primarily by rapid detoxification (non-target-site based) of mesotrione; additionally, increased HPPD gene expression (target-site based) also contributes to the resistance mechanism in the evolution of herbicide resistance in this naturally occurring weed species

Mesotrione carryover to soybeans

Mesotrione provides excellent residual control and breaks down readily in the soil provided there is sufficient moisture. Another important consideration is the rate of application, the timing of application, and soil characteristics likely influences the rate of degradation. Another possible consideration is the interaction of the atrazine included in Lumax with the mesotrione. Typically the mesotrione rate for a soil application of Callisto is approximately twice the rate when applied postemergence and is 0.24 and 0.1 lbs active ingredient/acre. The maximum rate of mesotrione in Lumax is 0.2 lbs active ingredient/acre

Physiological and Molecular Mechanisms of Differential Sensitivity of Palmer Amaranth (Amaranthus palmeri) to Mesotrione at Varying Growth Temperatures

Citation: Godar, A. S., Varanasi, V. K., Nakka, S., Prasad, P. V. V., Thompson, C. R., & Mithila, J. (2015). Physiological and Molecular Mechanisms of Differential Sensitivity of Palmer Amaranth (Amaranthus palmeri) to Mesotrione at Varying Growth Temperatures. Plos One, 10(5), 17. doi:10.1371/journal.pone.0126731Herbicide efficacy is known to be influenced by temperature, however, underlying mechanism(s) are poorly understood. A marked alteration in mesotrione [a 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor] efficacy on Palmer amaranth (Amaranthus palmeri S. Watson) was observed when grown under low- (LT, 25/15 degrees C, day/night temperatures) and high (HT, 40/30 degrees C) temperature compared to optimum (OT, 32.5/22.5 degrees C) temperature. Based on plant height, injury, and mortality, Palmer amaranth was more sensitive to mesotrione at LT and less sensitive at HT compared to OT (ED50 for mortality; 18.5, 52.3, and 63.7 g ai ha(-1), respectively). Similar responses were observed for leaf chlorophyll index and photochemical efficiency of PSII (F-v/F-m). Furthermore, mesotrione translocation and metabolism, and HPPD expression data strongly supported such variation. Relatively more mesotrione was translocated to meristematic regions at LT or OT than at HT. Based on T-50 values (time required to metabolize 50% of the C-14 mesotrione), plants at HT metabolized mesotrione faster than those at LT or OT (T-50; 13, 21, and 16.5 h, respectively). The relative HPPD: CPS (carbamoyl phosphate synthetase) or HPPD:beta-tubulin expression in mesotrione-treated plants increased over time in all temperature regimes; however, at 48 HAT, the HPPD:beta-tubulin expression was exceedingly higher at HT compared to LT or OT (18.4-, 3.1-, and 3.5-fold relative to untreated plants, respectively). These findings together with an integrated understanding of other interacting key environmental factors will have important implications for a predictable approach for effective weed management

Effects of Chronic Exposure to the Herbicide, Mesotrione, on Spiders

Mesotrione is a widely used agricultural herbicide and is frequently used alone or as an adjuvant for the herbicides glyphosate and atrazine. The effects of mesotrione are largely untested on beneficial non-target species such as spiders. Different spider species may be differentially susceptible due to size differences, microhabitat, and levels of exposure to this herbicide via soil contact. We tested mortality differences of seven species of spider when exposed to field-relevant concentrations of mesotrione-treated soil over a 55-day period. We tested the web-building spiders Frontinella pyramitela and Tetragnatha laboriosa. We also tested the stem and leaf-dwelling ambush spiders Mecaphesa asperata and Pisaurina mira and three species of ground-dwelling wolf spiders that vary in their burrowing propensities: Hogna lenta (infrequent burrower), Tigrosa helluo (facultative burrower) and a habitually burrowing wolf spider Trochosa ruricola. All seven of these species commonly occur in mesotrione-treated agricultural systems. We found that the web-building spider Frontinella but not Tetragnatha showed increased mortality compared to control treatments. Mecaphesa, Pisaurina, Trochosa, and Tigrosa all showed large significant increases in mortality under chronic exposure to mesotrione-treated soil whereas the wolf spider Hogna lenta was unaffected. We also found sex-specific mortality effects in Pisaurina with males having higher mortality. Several species showed significant shifts in space use when exposed to mesotrione and we found significant interaction between spider weight gain and herbicide treatment. In general, mesotrione is an unsafe herbicide for some species of spiders. Alternative herbicides to mesotrione should be considered to minimize the negative biocontrol impact on beneficial spiders within integrated pest management systems

Removal of Creeping Bentgrass from Kentucky Bluegrass with Mesotrione

Creeping bentgrass (Agrostis stolonifera L.) creates a dense, high-quality playing surface on golf courses, but often encroaches adjacent areas of Kentucky bluegrass (Poa pratensis L.). Callisto, a herbicide produced and marketed by Syngenta containing the active ingredient mesotrione, provides preemergence and postemergence control of broadleaf and annual grassy weeds. Preliminary field trials show that mesotrione kills creeping bentgrass, but more information is needed regarding the application protocol. Research was conducted to determine: 1) what rates of mesotrione are best for removing creeping bentgrass from Kentucky bluegrass, and 2) what mesotrione rates are safe for Kentucky bluegrass