• A Physiological Study of Developing Pods and Leaves Honey Mesquite

      Wilson, R. T.; Krieg, D. R.; Dahl, B. E. (Society for Range Management, 1974-05-01)
      Photosynthetic and respiratory rates of developing pods and fully expanded leaves of mesquite were assayed during 1972 to determine whether current photosynthesis was sufficient to supply the demands of the developing pods or whether reserve carbohydrates from the roots were required. Net photosynthetic rates of developing pods were very low when expressed as a function of dry weight, whereas the rates of CO2 evolution were high, suggesting a very active metabolic rate. Leaf photosynthetic rates were comparable to reported rates for other tree species. From the data collected, it was concluded that current photosynthate could not supply the amount of organic matter needed for pod development on trees possessing heavy fruiting loads, and reserve carbohydrates would be needed during the period of maximum rate of dry matter accumulation by the pods.
    • Bite-count vs Fecal Analysis for Range Animal Diets

      Sanders, K. D.; Dahl, B. E.; Scott, G. (Society for Range Management, 1980-03-01)
      This study indicated that the bite-count and fecal analysis methods give similar results for estimating major components of cattle diets in Texas. The bite-count method could not be used on large, brush-infested pastures with rough terrain; however, the fecal analysis method was easily used under such conditions. Other advantages of fecal analyses were: samples were collected with a minimum of field work, diets of wild and domestic animals could be obtained, and bad weather and poor field conditions were not problems. Major disadvantages of the fecal analysis technique were: forages with dense stellate trichomes were overestimated; mesquite beans were retained in the digestive tract for abnormally long periods; the laboratory phase required a trained technician; and the work was tedious.
    • Carbohydrate Concentrations in Honey Mesquite Roots in Relation to Phenological Development and Reproductive Condition

      Wilson, R. T.; Dahl, B. E.; Krieg, D. R. (Society for Range Management, 1975-07-01)
      Lower concentrations of total available carbohydrates were found throughout the growing season in roots of honey mesquite trees with many flowers and pods than in trees with a low reproductive potential. Following bud burst, during the period of pod elongation, mesquite trees with few reproductive organs replenished the root issue with carbohydrates faster than did trees bearing many reproductive organs. During the seed development phase of growth, a second decline in root carbohydrate concentrations occurred. This decline began approximately 1 week later in the heavily fruited trees compared to the trees with few pods. Variation in carbohydrate storage among trees differing in reproductive potential largely explains why it is difficult to consistently kill mesquite roots with growth regulating herbicides. When carbohydrates are no longer accumulating in the roots of trees with few flowers or seed pods, those trees with many reproductive organs may be accumulating carbohydrates. Since herbicides such as 2,4,5-T move to the roots when carbohydrates are accumulating, little herbicide would get to the roots in the one case. Optimum herbicide application dates for West Texas would generally occur from May 15 to June 15 and from July 1 to July 15.
    • Controlling Blowouts for Forage Production

      Everson, A. C.; Dahl, B. E.; Denham, A. H. (Society for Range Management, 1966-05-01)
      Blowouts on sandy soils in the Great Plains can be controlled by leveling hummocks and shaping sharp banks, developing sorghum stubble and seeding warm-season grasses into the stubble. This practice will provide grazeable forage and reduce damage to adjacent areas by wind-blown soil.
    • Economic Evaluation of Chemical Mesquite Control Using 2,4,5-T

      Ethridge, D. E.; Dahl, B. E.; Sosebee, R. E. (Society for Range Management, 1984-03-01)
      Honey mesquite (Prosopis glandulosa var. glandulosa) represents the most severe brush problem in the Texas Rolling Plains. Substantial research has been conducted on control methods, but economic analysis has been limited. The purpose of this study was to develop an evaluation model and evaluate the economic feasibility of 2,4,5-T (2,4,5-trichlorophenoxy acetic acid) for honey mesquite control in the Rolling Plains. The model is used to estimate the net present value of added grass production from treatment with 2,4,5-T over the life of the treatment; the central part of the model is the estimated herbage yield response function. The gross value of treatment with 2,4,5-T was estimated using different combinations of livestock price, top kill, canopy cover, and discount rate. Of the situations analyzed, gross value of mesquite control varied from a low of $22/ha to over $73/ha. These returns compare to current treatment costs of $22-25/ha.
    • Ecotypic Variation in Tripsacum dactyloides Evaluated in Texas

      Schliesing, T. G.; Dahl, B. E. (Society for Range Management, 1983-09-01)
      Eastern gamagrass collections (26) from throughout Texas, except the Trans-Pecos, and from southern Oklahoma (3) were evaluated in a common garden at Uvalde, Texas, to select an ecotype suitable for planting in central and south Texas. Four potential ecotypes existed among the collections with a fifth existing in collections from extreme southeast Texas. The characters of this latter type overlapped those of collections from north Texas making it less distinct from the others. Collections (Type C) from central and west Texas were superior to all others in forage production, crude protein, and chlorophyll content. Collections from near Baird and Bracketville were outstanding and further field evaluation is warranted.
    • Environmental Factors Related to Medusahead Distribution

      Dahl, B. E.; Tisdale, E. W. (Society for Range Management, 1975-11-01)
      Sites particularly susceptible to medusahead invasion in the more arid portions of Idaho were either those with well-developed soil profiles, particularly those with high clay content either at or near the surface; or those occupying topographic positions that received additional run-off from adjacent sites. In more mesic climates moderately well developed soils appeared as highly susceptible as the well-developed soils. Conversely, soils with little profile development, particularly those which were well drained, remained dominated by cheatgrass in early seral stages regardless of whether they were in the more arid or mesic areas. The nature of the surface geology as it influenced the soil texture derived therefrom was a valuable aid to identifying sites susceptible to medusahead. Maintaining a good stand of perennial vegetation appeared the best barrier to medusahead invasion into susceptible soils.
    • Evaluation of Rangeland Seedings Following Mechanical Brush Control in Texas

      Stuth, J. W.; Dahl, B. E. (Society for Range Management, 1974-03-01)
      Seeding success was evaluated on 62 ranches in Texas to compare relative success and costs of various treatments as affected by range site. Effects of precipitation and temperature were studied. Seeding during rootplow-rollerchop operations gave consistently better stands at a lower cost on all but the very shallow sites where seeding during treedozing treatments proved more economical. Relationships between site and factors affecting success differed distinctly between the wetter and drier portions of the study area. In the drier area, as soil depth decreased the amount of rainfall received close to the planting date aided seedling establishment more than did seedbed preparation. Cool temperatures favored seeding success on very shallow sites, but they were detrimental to seeding success on loamy bottomland sites. In the wetter area, degree of seedbed preparation was more important on all sites as long as sufficient rains for germination occurred within 90 days after planting. Mechanical brush control techniques that destroy most of the existing grass proved a hazardous undertaking, as half of the follow-up seedings were considered poor or total failures. This study separates those brush control practices and seeding techniques most likely to result in successful grassland restoration on west Texas brush-infested ranges from those less likely to provide successful seeded stands.
    • Factors Affecting Budbreak in Honey Mesquite in West Texas

      Goen, J. P.; Dahl, B. E. (Society for Range Management, 1982-07-01)
      Budbreak in honey mesquite in west Texas rarely occurs prior to the last spring frost. We monitored many trees from 1970 to 1980 attempting to better correlate mesquite mortality from herbicides to growth stage. In doing so, we found clues to the probable conditions triggering budbreak. Budbreak was closely correlated to daily minimum winter temperatures but totally unrelated to winter maximum, mean, or soil temperatures. Our data showed that the higher the number of consecutive days with minimums below -1°C during January 15 to February 14, the earlier spring budbreak would occur. Once chilling requirements were met, date of budburst then became a function of relatively warmer daily minimum temperatures from February 15 to March 15. Being able to predict budbreak (from equations developed herein) as early as February 15 and/or March 15 should give ranchers and herbicide applicators 4 to 6 weeks lead time in planning mesquite control programs.
    • Factors Affecting Mesquite Control with Tordon 225 Mixture

      Sosebee, R. E.; Dahl, B. E.; Goen, J. P. (Society for Range Management, 1973-09-01)
      The influence of various site characteristics was studied for Tordon 225 Mixture effectiveness in honey mesquite control in the Rolling Plains of Texas. Tordon 225 Mixture was commercially applied in 1970 at 0.5 lb a.e./acre under an experimental label for Texas. Generally, soil temperature (18-inch depth) above 75 degrees F, relatively low soil water content (0 to 6-inch depth), and tree height (less than 8 ft) were most influential in the root mortalities obtained in this study.
    • Factors affecting weeping lovegrass seedling vigor on shinnery oak range

      Matizha, W.; Dahl, B. E. (Society for Range Management, 1991-05-01)
      Low vigor of seedlings and stand failures plague many revegetation efforts in semiarid and arid rangelands. Phototoxicity, sandbur (Cenchrus incertus M.A. Curtis) competition, seedbed preparation (plowing vs. disking), and nitrogen (N) fertilization were studied as reasons for low vigor of Ermelo weeping lovegrass [Eragrostis curvula Schrad.) Nees] seedlings on sand shinnery oak (Quercus havardii Rydb.) range in west Texas. Oak leaf residue and sandbur-dominated grass residue extracts did not affect seed germination and initial shoot growth of lovegrass seedlings. However, these residue extracts reduced root length 92% and 21%, respectively. Survival of weeping lovegrass seedlings was not affected by even 65 sandbur plants/m2. But, herbage yield was reduced 65, 72, and 79% with 30, 45, and 65 sandbur plants/m2. Early in the growing season, unfertilized plowed (P) plots had 5.6 ppm N in the 10-20 cm soil layer compared to a maximum of 3.9 ppm on other seedbed treatments. In the surface 10 cm, the P plots had less N than the disked plots. Surface-applied N fertilizer accumulated in the upper 10 cm of soil and promoted weed growth without improving weeping lovegrass stands or seedling vigor. Weeping lovegrass seedling vigor was greatest on P and least on disked plots. Thus, plowing buried weed seeds better, put resident N more deeply into the soil for better root uptake, removed allelopathic residues from seedling contact better, and provided for much higher seedling vigor than the disked seedbeds.
    • Germination and Emergence of Different Age Seeds of Six Grasses

      Shaidaee, G.; Dahl, B. E.; Hansen, R. M. (Society for Range Management, 1969-07-01)
      Different aged seeds of six grass varieties were tested for percentage laboratory germination and percentage field emergence. Best age of seed for planting differed greatly among the varieties and the results from laboratory and field tests were not always consistent. One-year-old seeds of sand bluestem, blue grama and A-6606 switchgrass; two-year-old side-oats grama and yellow indiangrass; and seven-year-old Grenville switchgrass seeds had emerged best at the end of the field test. Except for sandhill bluestem, seeds two years and older emerged faster, a factor that may be important in successful field establishment of seeded grasses.
    • Influence of Site on Mesquite Mortality from 2,4,5-T

      Dahl, B. E.; Wadley, R. B.; George, M. R.; Talbot, J. L. (Society for Range Management, 1971-05-01)
      Soil temperature at the 18-inch depth was the most important factor affecting response of honey mesquite to 2,4,5-T application. Temperatures at this depth in the high 60's F or low 70's F resulted in no mesquite kills with the best results obtained if temperatures were over 80 F. Phenological development was essentially as important with plants having mature leaves and seed pods being easiest to kill. Trees with small and blooming spikes and those without flowers or pods were hardest to kill with 2,4,5-T. Other variables usually considered important, such as soil moisture, were important only in combination with other variables. Mesquite trees growing on upland and sandy sites are apparently more susceptible to 2,4,5-T largely because the soil is usually several degrees F warmer than bottomland and clay sites.
    • Integration of Cattle Production and Marketing Strategies with Improved Pastures and Native Range

      Ethridge, D. E.; Nance, J. D.; Dahl, B. E. (Society for Range Management, 1987-05-01)
      Forty-eight stocker cattle enterprises on tobosagrass, bluestem, and lovegrass pastures being bought and sold at different points in the seasonal cattle price cycle were evaluated to determine the set of enterprises which maximize ranch profits. All optimal plans for the 397-ha (980 ac) ranch included enterprises which showed ranch profit gains from forfeiture of some physical weight gains for the price advantages of off-season buying/selling.
    • Nutritional Characteristics of High Yielding Exotic Grasses for Seeding Cleared South Texas Brushland

      McCawley, P. F.; Dahl, B. E. (Society for Range Management, 1980-11-01)
      Three exotic grasses potentially useful converting south Texas brush rangeland to permanent pasture were evaluated in 1976 and 1977. Yearling cattle required 16.6, 23.1, and 34.8 kg of forage per kg of gain for coastcross-1 bermudagrass, kleingrass-75, and Bell rhodesgrass, respectively. Cattle gained 0.68, 0.56, and 0.33 kg/head daily grazing these species. They ate (forage disappearing) about 12 kg/head daily regardiess of species, so daily gains directly reflected differences in quality among the forages. Our data suggest that the quality measure most nearly deficient was the factor most limiting animal performance, e.g., correlation between average daily gain and P content was r = 0.89 for cattle grazing Bell rhodesgrass. Its P content varied from 0.16 to 0.06% from spring to fall compared to 0.24 to 0.15% from spring to fall for the other two forages. Overall, 24-hr IVDMD (fermentation only) best correlated with animal daily gain. Generally, Bell rhodegrass had lowest, coastcross-1 bermudagrass highest, and kleingrass-75 intermediate quality values, particularly for digestibility, crude protein, and digestible energy. Dry matter yields were 9.6, 11.6, and 11.8 thousand kg/ha for coastcross-1 bermudagrass, kleingrass-75, and Bell rhodesgrass in 1976.
    • Seasonal Food Preferences of Cattle on Native Range in the South Texas Plains

      Everitt, J. H.; Gonzalez, C. L.; Scott, G.; Dahl, B. E. (Society for Range Management, 1981-09-01)
      Cattle diets were studied on a predominantly native range in Hidalgo County, which is in the extreme southern part of Texas, from September, 1976, to November, 1977. Microhistological examination of cattle feces was used to determine the botanical composition of diets. Percentages of grasses, forbs, and browse consumed by cattle for the fall of 1976 and the winter, spring, summer, and fall of 1977, respectively, were: grasses-77.9, 81.2, 84.9, 65.1, 63.6; forbs-20.2, 6.9, 13.4, 31.6, 34.8; and browse-2.0, 11.9, 1.7, 3.3, 1.6. Cattle showed an increasing preference for forbs during the summer and fall of 1977 as the availability of several grass species decreased. Roemer three-awn, red lovegrass, and hooded windmillgrass were the most utilized species, but they were eaten in about equal proportion to their availability. Buffelgrass, common Bermudagrass, and sedges were eaten in lesser amounts but were highly preferred. Perennial forbs, especially spreading sida and orange zexmenia were important components of the summer and fall diets. Pricklypear was the only important browse species which was important only in winter. These data indicated that perennial grasses made up the bulk of cattle diets on a predominantly native range in south Texas; however, perennial forbs were important seasonally.
    • Will Mesquite Control with 2,4,5-T Enhance Grass Production?

      Dahl, B. E.; Sosebee, R. E.; Goen, J. P.; Brumley, C. S. (Society for Range Management, 1978-03-01)
      Both honey mesquite density and percent of plants dead the year of aerial spraying with 2,4,5-T proved to be major factors influencing perennial grass production. Sites with sparse honey mesquite stands and very dense stands (over 50% canopy cover) yielded little extra grass after 2,4,5-T application. Heavy mesquite foliage probably prevented adequate leaf coverage with 2,4,5-T in dense stands, and in sparse stands mesquite competed little with the herbaceous plants. Increased perennial grass production of about 540 lb/acre/year would be necessary over a 5-year period to break even with a $4.60/acre aerial application of 2,4,5-T. With honey mesquite cover of 30%, a plant kill over 80% the year of application was required to provide a 540 lb/acre/year grass increase. However, a 90% kill would provide nearly 750 lb/acre/year extra perennial grass. Thus, paying particular attention to optimum environmental factors and proper timing for the 2,4,5-T application can pay big dividends.
    • Winter forb control for increased grass yield on sandy rangeland

      Dahl, B. E.; Mosley, J. C.; Cotter, P. F.; Dickerson, R. L. (Society for Range Management, 1989-09-01)
      Four separate studies evaluated several herbicides for reducing competition from overwintering weeds on sandy rangeland in west Texas. Air temperature was 10 degrees C with soil moisture adequate for plant growth at herbicide application (0.28 kg ae/ha) on 14 March 1985. Trichlopyr ([3,5,6-trichloro-2-pyridinyl)oxy]acetic acid); 2,4-D [(2,4-dichlorophenoxy)acetic acid]; and dicamba (3,6-dichloro-2-methoxybenzoic acid) plus 2,4-D were ineffective, while picloram 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid); picloram plus 2,4-D; and dicamba alone adequately controlled western ragweed (Ambrosia psilostachya DC.), the major targeted weed. These treatments were repeated on 4 April 1986 when air temperature was 24 degrees C but with dry surface soils. Results were similar to those of 1985, except trichlopyr also controlled western ragweed under the warmer temperature. In another study, various rates of picloram and trichlopyr aerially applied 5 April 1986 showed that 0.07 kg ae/ha of picloram or 0.28 kg ae/ha of trichlopyr reduced (P < 0.05) western ragweed with a corresponding increase in grass production. Picloram more effectively controlled targeted forbs while trichlopyr suppressed sand shinnery oak (Quercus havardii Rydb.) more effectively. Two companion studies also evaluated picloram and picloram plus 2,4-D. In one study 0.28 kg ae/ha of picloram was applied to sand shinnery oak range on 11 March 1985. Grass yield increased from 359 kg/ha in untreated plots to 1,222 kg/ha in treated plots. Grass yield in treated areas remained greater (P < 0.05) for 3 growing seasons post-treatment. Sand shinnery oak plants at the bud burst stage were top-killed by picloram. On 14 March 1985 picloram (0.056 kg ae/ha) plus 2,4-D (0.224 kg ae/ha) was applied to sand shinnery oak rangeland. This treatment reduced forb production with a corresponding increase in grass production the year of application (P < 0.05), but effects did not persist into the second growing season. Picloram plus 2,4-D did not suppress sand shinnery oak.