@article {JRN54522, title = {Effect of light intensity and wavelength on concentration of plant secondary metabolites in the leaves of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {65}, year = {2016}, month = {04/2016}, pages = {108-114}, chapter = {108}, abstract = {

Flourensia cernua (tarbush) is a shrub that has encroached into grasslands in many areas of the northern Chihuahuan Desert and contains high levels of carbon-based secondary compounds. Concentrations of secondary compounds are affected by numerous biotic and abiotic influences, including amount and wavelength of solar radiation. However, responses to shade and ultraviolet light restriction are inconsistent among plant species and compound class. We conducted a three-year study to evaluate the effect of shade and UV light restriction on total phenolic and terpene concentrations in tarbush. Sixty plants were randomly assigned to one of three treatments (control, UV light restriction, or 50\% incident light restriction). Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Total phenolics did not differ between UV-restricted and control plants, but were lower in shaded plants than the other treatments (P \< 0.05).\  Total volatiles tended to be greater for the UV-restricted treatment than control plants (P= 0.056), with shaded plants not different from either treatment. Treatment effects were detected for 18 individual compounds (P \< 0.05). Our results partially support the hypothesis that UV restriction and shading alter carbon-based secondary chemical concentrations.

}, keywords = {Flourensia cernua, phenolics, plant secondary metabolites, shade, terpenes, ultraviolet light}, doi = {10.1016/j.bse.2016.02.019}, url = {/files/bibliography/16-006.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James} } @article {49847, title = {Within-plant distribution of volatile compounds on the leaf surface of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {48}, year = {2013}, month = {01/2013}, pages = {144-150}, chapter = {144}, abstract = {

We are using Flourensia cernua as a shrub model to study the role of terpenes on intake by livestock. Two experiments were conducted to examine distribution of volatile chemicals within a plant in an effort to minimize sample variability. In Exp. 1, leaves (current year\&$\#$39;s growth) were collected from 20 tarbush plants. Two leaders were sampled from each of three positions (outer canopy, subcanopy, and basal) in all four quadrants (based on ordinal direction). In Exp. 2, 10 leaders of current year\&$\#$39;s growth were removed from another 20 plants. Leaders were collected from the outer canopy of each quadrant and separated into thirds before removing leaves, thereby creating three leaf age categories. Volatile compounds were extracted with ethanol and analyzed with gas chromatography/mass spectrometry. Ninety-four chemicals (including 15 unknowns) were present on the leaf surface of F. cernua. Although 14 and 21 compounds differed (P \< 0.05) among quadrants in Exp. 1 and 2, respectively, no consistent quadrant effect was detected in either study. Leaf position differed (P \< 0.05) for 52 chemicals in Exp. 1 but outer canopy and subcanopy leaves differed for only 10 compounds. In Exp. 2, 63 compounds differed among leaf age categories. Immature leaves contained greater concentrations of 46 chemicals (P \< 0.05) than moderate or mature age categories, but moderate and mature leaves differed for only seven compounds. Estimated total concentration (i.e., cumulative concentration of all compounds) was not affected by leaf position but varied among leaf age categories (P \< 0.05; immature \> moderate \> mature). Differences in leaf position were attributed about equally to mono- and sesquiterpenes, whereas leaf age was affected to a greater extent by sesquiterpenes. Leaf position and maturity both affect terpene concentration and sampling variability for tarbush. However, little difference was detected between subcanopy and canopy positions. Thus, by avoiding basal sprouts and sampling from the mid-point of current year\&$\#$39;s growth, sampling variation should be minimal.

}, keywords = {Flourensia cernua, leaf age, plant secondary metabolites, terpenes, volatiles, within-plant distribution}, doi = {10.1016/j.bse.2012.11.020}, url = {/files/bibliography/13-002.pdf}, author = {Richard E. Estell and D. K. James and E.L. Fredrickson and D.M. Anderson} } @article {50329, title = {Volatile compounds on the leaf surface of intact and regrowth tarbush (Flourensia cernua DC) canopies}, journal = {Journal of Chemical Ecology}, volume = {33}, year = {2007}, month = {September 25, 20}, pages = {1867-1875}, abstract = {

Shrub expansion into desert grasslands is a serious problem resulting in loss of forage and rangeland productivity. Flourensia cernua DC (tarbush) is one such shrub contributing to the decline of Chihuahuan Desert grasslands. Our previous research has shown tarbush consumption by sheep and goats to be negatively related to leaf surface concentration of individual terpenes and epicuticular wax. Concentrations of compounds such as terpenes often change with plant age and phenology. Our objective was to examine the effect of altering the vegetative state of tarbush on volatile chemicals. Ninety tarbush plants were randomly selected and all biomass within 10 cm of the soil surface was removed from 45 plants during winter dormancy. Leaves were collected the following summer during active growth from the canopy of intact controls and resprouts. Leaf surface volatiles were analyzed by gas chromatography-mass spectroscopy and subjected to univariate analysis of variance and stepwise discriminate analysis. Of the 87 compounds present on tarbush leaves, 35 were greater in canopy samples and 16 were greater in regrowth samples based on univariate analysis (P\< 0.05). Mean concentration of total volatiles on canopy leaves tended to be less (P = 0.062) than that of regrowth (3642 vs. 4684 {\`\i}g/g DM). Nine compounds in the discriminant analysis ({\'a}-muurolene, iso-borneol, unknown$\#$6, p-cymen-8-ol, unknown$\#$7, sabinene, {\^a}-caryophyllene, {\"a}-cadinene, and {\'a}-copaene) explained 95\% of the variation between canopy and regrowth samples. Lower cumulative concentration of volatile compounds in canopy than regrowth samples suggests repsrouts may be less vulnerable to herbivory than intact tarbush.

}, keywords = {Flourensia cernua, plant secondary metabolites, regrowth, tarbush, terpenes}, doi = {10.1007/s10886-007-9360-8 }, url = {/files/bibliography/07-029.pdf}, author = {E.L. Fredrickson and Richard E. Estell and M.D. Remmenga} } @article {50380, title = {Jackrabbit (Lepus californicus) herbivory changes dominance in desertified Chihuahuan Desert ecosystems.}, journal = {Journal of Arid Environments}, volume = {70}, year = {2007}, month = {03/2007}, pages = {418-426}, abstract = {This study addressed the question: can herbivory by a medium size herbivore, black-tail jackrabbits (Lepus californicus), change dominance in desertified ecosystems dominated by two species of shrubs. Shrubs that were pruned by jackrabbits in plant communities dominated by creosotebush (Larrea tridentate) and tarbush (Flourensia cernua) were compared to shrubs not browsed by the rabbits. In the missed shrub area, herbivory on F. cernua resulted in death of 46.6\% of the shrubs, compared to only 4.8\% of L. tridentate shrubs. There was no evidence of jackrabbit browsing of dead F. cernua in a tarbush monoculture area. The canopy volumes of F. cernua plants that survived repeated browsing were significantly smaller than predicted based on unbrowsed plants with the same basal stem areas. Jackrabbit browsing resulted in increased canopy volume of creosotebush shrubs. Creosotebush average canopy volume significantly exceeded predicted values because of compensatory growth of stems from nodes below the severed point. Close spatial association of lightly browsed creosotebush with heavily browsed tarbush may be a factor contributing to low utilization of creosotebush stems by jackrabbits. Differential browsing by the rabbits is shifting thee ecosystems toward an L. tridentate monoculture.}, keywords = {browsing, compensatory growth, creosotebush, Flourensia cernua, Larrea tridentata, preferential feeding, tarbush}, doi = {10.1016/j.jaridenv.2007.01.009}, url = {/files/bibliography/07-016.pdf}, author = {Roth, G.A. and Walter G. Whitford and Yosef Steinberger} } @article {50488, title = {Spatial variation in remnant grasses after a grassland-to-shrubland state change: Implications for restoration}, journal = {Rangeland Ecology and Management}, volume = {59}, year = {2006}, month = {July 2006}, pages = {343-350}, abstract = {

Around the world rangelands that have been degraded, such as historical desert grasslands now dominated by woody shrubs, are resistant to restoration efforts. The goal of this descriptive research was to examine the potential for black grama (Bouteloua eriopoda [Torr.] Torr.) recovery by remnant plants in a degraded area as a function of plant location across a landscape. Our objectives were 1) to document the historical dominant vegetation as a perennial grassland and determine broad-scale changes in dominance through time and 2) to examine fine-scale patterns of black grama presence and basal area with respect to microenvironmental conditions that indicate the landscape positions favorable for restoration. Historical vegetation maps starting in 1858, a field survey in 2002{\textendash}2003 of the location of all individual black grama plants in a 29-ha area, and spatial data layers in a geographic information system were used to address these objectives. Upland grasses, including black grama, dominated the study site in 1858, although tarbush (Flourensia cernua DC.) was the dominant species by 1915, and creosotebush (Larrea tridentata [DC.] Cov.) is the current dominant. A total of 3 334 black grama plants were found for an average density of 0.01 plants{\textperiodcentered}m-2. High spatial variation was found in the occurrence and basal area of black grama plants that was related to water availability rather than livestock grazing: most plants were found in or adjacent to an arroyo (67\%), at a northern aspect (47\%), and outside experimental exclosures established in 1930 (43\%). Largest average basal areas were found in the livestock exclosure, and in general, average basal area was not related with aspect or canopy microsite. These remnant plants can be used as propagule sources in restoration efforts, and information on microsite conditions for black grama survival can be used to improve restoration potential for similar sites.

}, keywords = {Bouteloua eriopoda, Flourensia cernua, Larrea tridentata, perennial grasslands, shrub invasion}, doi = {10.2111/05-202R1.1}, url = {/files/bibliography/06-028.pdf}, author = {Debra C. Peters and Mariotto, I. and Kris Havstad and Murray, L.M.} } @article {51071, title = {The effect of feeding ewe lambs a 15\% tarbush (Flourensia cernua DC) pellet pre- and post-weaning on the subsequent diet selection of tarbush}, journal = {Journal of Arid Environments}, volume = {44}, number = {1}, year = {2000}, month = {January 1, 2000}, pages = {123-131}, abstract = {

The shrub Flourensia cernua (tarbush) has rapidly increased in dominance within Chihuahuan Desert grasslands, and is comparable to alfalfa in nutrient density. Increasing tarbush in livestock diets may improve diet quality, while decreasing tarbush dominance. We determined dietary preference for tarbush by sheep and the effect of previous exposure on preference. Thirty-eight ewe lambs received either tarbush or alfalfa in sorghum-based pellet 120 days postparturition; after which, dietary preference was assessed. Previous exposure averted lambs from tarbush consumption. Lambs without previous exposure maintained greater intakes initially, but declined with time. This decline corresponds with onset of tarbush toxicosis.

}, keywords = {ewe lambs, Flourensia cernua, post-weaning, pre-weaning, tarbush}, doi = {10.1006/jare.1999.0571}, url = {/files/bibliography/00-003.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @article {51213, title = {Relationship of tarbush leaf surface terpene profile with livestock herbivory}, journal = {Journal of Chemical Ecology}, volume = {24}, number = {1}, year = {1998}, month = {January 1, 1998}, pages = {1-12}, abstract = {

Tarbush (Flourensia cernua DC.) is a Chihuahuan Desert shrub with a resinous leaf surface containing terpenes that may affect livestock herbivory. Cattle, sheep, and goats were densely stocked in paddocks containing tarbush in two consecutive years for six to nine days and defoliation of 160 plants was recorded daily. Plants were categorized as exhibiting high or low defoliation. Leaves were collected from these plants the third year for chemical analysis. A selection procedure was used to generate two variable sets closely related to defoliation category. One set contained 14 variables (dry matter, ash, -pinene, sabinene, 3-carene, p-cymene, limonene, camphor, bomeol, cis-jasmone, {\^a} -caryophyllene, alpha-humulene, ledene, and flourensadiol) and the other set contained 14 unidentified compounds. When subjected to multivariate analysis, each group distinguished between the two defoliation categories (P \<0.001 and P \<0.0019 for known and unknown variable sets, respectively). These data support the hypothesis that leaf surface chemistry of individual tarbush plants is related to extent of defoliation by livestock.

}, keywords = {diet selection, Epicuticular wax, Flourensia cernua, leaf surface chemistry, monoterpenes, sesquiterpenes}, doi = {10.1023/A:1022399426352 }, url = {/files/bibliography/608.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51322, title = {Tarbush leaf surface terpene profile in relation to mammalian herbivory}, year = {1996}, note = {NOT A DUPLICATE OF RECORD $\#$474}, month = {1996}, pages = {237-241}, publisher = {US Forest Service}, edition = {Gen. Tech. Rep. INT-GTR}, abstract = {

Cattle, sheep and goats were densely stocked in pad- docks containing tarbush (Flourensia cernua DC) for six to nine days and defoliation of 160 plants was recorded daily during two years. Plants were separated into high, moderate or low defoliation categories. Leaves were collected from plants during the same stage of maturity during the third year. Leaf surface compounds were extracted with ethanol and mono- and sesquiterpenes were ana-lyzed using gas chromatography/ion trap mass spectrometry. A set of 11 variables was identified that appeared most closely related to plant defoliation categories: dry matter, ash, limonene, camphor, borneol, a copaene, B caryophyllene, a pinene, p-cymene, cis-jasmone and caryophyllene oxide concentrations. This group distinguished among all three defoliation categories (P \< 0.03) when subjected to multivariate analysis. These data support the hypothesis that leaf surface chemistry is related to degree of defoliation of individual tarbush plants by livestock.

}, keywords = {diet selection, Epicuticular wax, Flourensia cernua, leaf surface chemistry, monoterpenes, sesquiterpenes}, url = {/files/bibliography/512.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51332, title = {Structure and function of C3 and C4 Chihuahuan Desert plant communities: Standing crop and leaf area index}, journal = {Journal of Arid Environments}, volume = {34}, number = {1}, year = {1996}, month = {September 1, 199}, pages = {47-62}, abstract = {

During the past 150 years, native C3 shrubs have invaded and dominated extensive areas of former C4 grasslands in deserts of the south-western United States. This vegetation shift has caused large changes in several aspects of the structure and function of these plant communities. To examine structural changes, we measured the standing crop of green herbaceous plants and live shrubs, leaf area index (LAI), and canopy cover and shrub density in grass and shrub plant communities that exist on sandy and clay soils in the Chihuahuan Desert. Standing crop ranged from 800 to 1800 kg ha-1 for grass communities and from 2800 to 3500 kg ha-1 for shrub communities. The LAI in grass communities was typically 0{\textperiodcentered}1 to 0{\textperiodcentered}2 and in shrub communities was 0{\textperiodcentered}3 to 0{\textperiodcentered}4. Averaged over the 2 years, the greatest LAI was in the shrub community on a clay soil that also had a herbaceous understory. Shrub canopy cover varied from 17\% (Flourensia cernua, tarbush) to 33\% (Prosopis glandulosa, honey mesquite). On sandy soils, this vegetation shift has resulted in a replacement of herbaceous vegetation with shrubs and a large reduction in species diversity, while on clay soils, due to greater soil fertility and soil water availability, there was only a slight decrease in herbaceous vegetation and little change in species diversity. This vegetation shift of desert grasslands has dramatically changed plant community structure.

}, keywords = {Bouteloua eriopoda, desert grasslands, Flourensia cernua, Larrea tridentata, Pleuraphis mutica, prosopis glandulosa, shrub invasion}, url = {/files/bibliography/483.pdf}, author = {Gibbens, Robert P. and Hicks, R.A. and W.A. Dugas} } @article {51362, title = {Stemflow, throughfall and channelization of stemflow by roots in three Chihuahuan Desert shrubs}, journal = {Journal of Arid Environments}, volume = {32}, year = {1996}, month = {1996}, pages = {271-287}, abstract = {

Three studies were conducted to examine precipitation{\textendash}vegetation relationships in the multi{\textendash}stemmed shrubs Larrea tridentata, Prosopis glandulosa and Flourensia cernua in a desert ecosystem. We measured stemflow and throughfall as affected by bulk precipitation, canopy architecture and stem-angles. Using fluorescent dye, we traced root channelization of stemflow water. Stepwise regression analysis showed that the best one-variable model for stemflow in L. tridentata was canopy volume, which accounted for 87\% of variation. The best one-variable model for stemflow in P. glandulosa and F. cernua was canopy area, which accounted for 82\% of variation in both species. Stemflow data from winter and summer months were statistically compared to determine the influence of leaves on stemflow generation in P. glandulosa and F. cernua. Stemflow amounts collected during winter months do not differ significantly from those of summer months demonstrating that in these winter deciduous species the absence of leaves during winter months does not affect generation of stemflow. Analysis of variance showed that the percentage of throughfall was different among species suggesting that variations in canopy characteristics could explain, in part, these interspecific throughfall differences. Both stem-angle and stem-length had a significant effect on stemflow generation in F. cernua and L. tridentata, whereas there was only a significant relationship between stem-angle and stemflow in P. glandulosa. Analysis of rhodamine-B dye distribution under shrubs indicated that root channels are preferential pathways for movement of stemflow water into soil, and that this water is potentially the source of soil moisture which allows shrubs to remain physiologically active under drought conditions.

}, keywords = {Chihuahuan Desert, Flourensia cernua, Larrea tridentata, prosopis glandulosa, root channelization, stemflow, throughfall}, doi = {10.1006/jare.1996.0023}, url = {/files/bibliography/500.pdf}, author = {E. Martinez-Meza and Walter G. Whitford} } @article {51439, title = {Effects of organic solvents on use of tarbush by sheep}, journal = {Journal of Chemical Ecology}, volume = {20}, number = {5}, year = {1994}, month = {1994}, pages = {1137-1142}, abstract = {

Tarbush (Flourensia cernua DC) is a native perennial shrub prevelant in many parts of the Chihuahuan desert. Ruminants have exhibited limited use of tarbus leaves and new leaders as a forage during the summer growing season. Efforts to increase use of tarbush by lambs, through spraying with various organic solvents were unsuccessful. probably because of the highly variable response. However, complete immersion of tarbush in organic solvents (acetone and ethanol) increased (P\< 0.01) tarbush use by ram lambs when compared to unaltered tarbush using organic solvents enhanced acceptability of tarbush to sheep.

}, keywords = {Flourensia cernua, herbivory, leaf surface, organic solvents, sheep, tarbush}, doi = {10.1007/BF02059749}, url = {/files/bibliography/416.pdf}, author = {Richard E. Estell and D.M. Anderson and Kris Havstad} } @article {51440, title = {Secondary chemistry of the leaf surface of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {22}, number = {1}, year = {1994}, month = {1994}, pages = {73-77}, abstract = {

Epicuticular wax accounted for 9.2\% fo the dry weight of whole Flourensia cernua (tarbush) leaves. Leaf surface extracts of tarbush were analyzed for mono- and sesquieterpenoids with gas chromatography/mass spectrometry. Camphene, $\#$ mycrene, 3-carene, limonene, 1,8-cineole, borneol, cis jasmone, $\#$ caryphyllene, caryophyllene oxide and globulol were consistently present in tarbush. Concentrations of several unidentififed compunds were estimated. A great deal of plant to plant variability was detected in leaf surface mono= and sesquietepenoid concentration. Infomation obtained on surface chemistry might be exploited to enhance use of tarbush as a forage for domestic herbivores.

}, keywords = {epicuticular waxes, Flourensia cernua, leaf surface chemistry, monoterpenoids, sesquiterpenoids}, doi = {10.1016/0305-1978(94)90116-3}, url = {/files/bibliography/419.pdf}, author = {Richard E. Estell and Kris Havstad and E.L. Fredrickson and Gardea-Torresdey, J.L.} } @article {51443, title = {Effects of chronic ingestion of tarbush (Flourensia cernua) on ewe lambs}, journal = {Veterinary and Human Toxicology}, volume = {36}, number = {5}, year = {1994}, month = {1994}, pages = {409-415}, abstract = {

Efforts to increase livestock utilization of tarbush are being coupled with studies to examine tarbush toxicity. Thirty-eight (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based growing ration. Lambs were pen-fed this diet 60 d pre-weaning and 60 d post-weaning. No differences existed between treatments in feed consumption. In the tarbush group, 1 lamb died of unknown causes at 90 d of age, while 3 lambs died between 115 and 120 d of age. There were no deaths in the alfalfa group. Shortly before death, lambs fed tarbush appeared lethargic, disoriented and anorectic. At 122 d of age, 5 lambs were randomly selected from each group. Feces and jugular blood samples were obtained from each lamb before being euthanized and necropsied the following day. All fecal samples were negative for occult blood. Serum gamma glutamyl-transpeptidase (P\  \<\  0.001) and aspartate aminotransferase (P\  \<\  0.001) activities and platelet counts (P\  \<\  0.05) were elevated in lambs fed tarbush, while serum calcium concentrations tended (P\  \<\  0.10) to be greater. Histologic examination revealed diffuse liver apoptosis in lambs fed tarbush. These data indicate tarbush leaves cause liver damage when fed for extended periods of time.

}, keywords = {chronic ingestion, ewe lambs, Flourensia cernua, tarbush}, url = {/files/bibliography/421.pdf}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Kris Havstad} } @article {51772, title = {Field-scale tebuthiuron application on brush-infested rangeland}, journal = {Weed Technology}, volume = {1}, year = {1987}, month = {1987}, pages = {323-327}, abstract = {

The objective of this study was to determine the effectiveness of tebuthiuron \ {N- [5-(1,1-dimethylethyl)-1, 3,4- thiadiazol- 2- yl) -N,N{\textquoteright} -dimethylurea} to treat brush-infested arid rangeland under field-scale conditions. A 130- ha tract in southern New Mexico dominated by creosotebush \ [Larrea tridentata (Sesse \& Moe. ex DC.) Coville $\#$3 LARTR] was treated with pelleted tebuthiuron at 0.4 kg ai/ha. After the fourth season following treatment, control of creosotebush, honey mesquite (Prosopis glandulosa Torr. $\#$ PRCJG), and tarbush (Flourensia cernua DC. $\#$ FLOCE) was 87, 48, and 100\%, respectively. Total shrub density was reduced from 4440 plants/ha to 570 plants/ha. Grass basal area increased from 1.1 to 3.4\%. The treatment did not affect forbs greatly. Total herbaceous above-ground biomass production in the fourth season after treatment was 860 kg/ha compared to 140 kg/ha on an adjacent untreated area. Perennial grass production was nearly 11- fold greater on the treated area than on the untreated area.

}, keywords = {arid rangeland, FLOCE, Flourensia cernua, grass cover, Larrea tridentata, LARTR, PRCJG, prosopis glandulosa}, doi = {10.1017/S0890037X00029833}, url = {/files/bibliography/314.pdf}, author = {Gibbens, Robert P. and C.H. Herbel and J.M. Lenz} } @article {52409, title = {Herbicide evaluation studies for the control of tarbush (Flourensia cernua)}, year = {1969}, month = {1969}, pages = {27}, institution = {Research Progress Report, Western Society of Weed Science}, abstract = {

Tarbush is a deciduous desert species which is found in dense stands on silty or clay loam sites on flood plains. The date of leaf emergence is dependent upon adequate soil mosture, so in some droughty years it may not leaf out until the summer rains occur. The studies reported were carried out on the Jornada Experimental Range near las Cruces, New Mexico, from 1961 through 1965 to determine the best time for treatment and the best herbicides for selective control. Treatments were applied semi-monthly on 1/100 A plots using a simulated aerial application from July through October in 1961 and 1965. Treatments were initiated in August 1962, on May 7, 1963, and on June 3, 1964. Defoliation estimates were made approximately 2 years after treatments were applied. The 1961 treatments included 2,4-D, 2,4-DP, 2,4,5-T, silvex, 2,3,6-TBA and amitrole-T at 1/2 lb/A. Dicamba was added to the list of test materials in 1962 and picloram was added in 1963. Herbicides were applied on all spray dates at 1/2 lb/A in 1962, 1 lb/A in 1963 and 1 1/2 lb/A in 1964 and 1965. Additional treatments with higher rates of herbicides were applied on one spray date ind 1962, 1963 and 1964. The defgree of defoliation was quite variable between dates of application with the September treatments being most toxic generally. At rates up to 2 lb/A, the phenoxy herbicides and amitrole-T usually gave less than 30\% defoliation. Dicamba was the most toxic material, causing 70\% defoliation on one or more spray dates each year. Increasing the rate of dicamba from 1/2 to 2 lb/A increased the degree of defoliation only when treatment was not on the optimum date. At comparable rates, picloram and 2,3,6-TBA were much less effective than dicamba.

}, keywords = {control, evaluation, Flourensia cernua, herbicide, tarbush}, url = {/files/bibliography/113.pdf}, author = {W. L. Gould and C.H. Herbel} } @article {52466, title = {Tarbush [Flourensia cernua (DC.)]}, year = {1966}, month = {1966}, pages = {38 }, publisher = {U.S. Department of Agriculture and U.S. Department of the Interior, Chemical Control of Range Weeds, Interagency Report}, abstract = {Tarbush, a member of the composite family (sunflower tribe), is a common deciduous shrub, usually less than 3 feet tall, that grows on an estimated 13,250,000 acres from western Texas to southeastern Arizona. It generally invades on the more productive flood plain sites and spreads from seed. As it gains dominance, forage production is greatly reduced. Tarbush is practically worthless for browsing. Individual plant treatments with fenuron pellets, monuron powder, fenuron-trichloroacetate (TCA) granules, and monuron-TCA granules have consistently given plant kills in excess of 90 percent. Trichlorobenzoic acid granules have been less effective. An effective rate is an individual plant treatment of 2 grams active ingredient of fenuron pellets, monuron powder, fenuron-TCA granules, or monuron-TCA granules. The materials should be scattered around the base of the plant. Since these materials are desensitized by light and high temperatures, it is important that they be applied just before or early in an expected rainy season. This method is economical in controlling sparse stands of tarbush. It would be especially beneficial in areas where tarbush is invading grassland. The work reported was done on a silt loam soil in southern New Mexico.}, keywords = {description, Flourensia cernua, government publication, plant treatment, tarbush}, url = {/files/bibliography/097.pdf}, author = {C.H. Herbel} }