Locations In Texas Research Articles

BancorpSouth Inc.

AbstractCommercial Banking (MIC: 8.1 SIC: 6022 NAIC:522110)BancorpSouth is a bank holding company headquartered in Tupelo, MS with assets of $10.31 billion and total deposits of $8.60 billion as of Dec 31 2003. Co. operates 246 commercial banking, insurance, trust, broker/dealer and consumer finance locations in Mississippi, Tennessee, Alabama, Arkansas, Texas and Louisiana. Co. and its subsidiaries provide a range of financial services to individuals and small‐to‐medium size businesses. Co. operates investment services, consumer finance, credit insurance and insurance agency subsidiaries. Co.'s trust department offers a variety of services including personal trust and estate services, and certain employee benefit accounts and plans.

Aflatoxin Accumulation in Maize Hybrids of Different Maturities

The incidence and severity of preharvest aflatoxin is greater under drought conditions, which commonly occur late in the growing season of south and central Texas. To determine if early maturation could be used as a means of disease escape, aflatoxin contamination was measured in early‐, intermediate‐, and full‐season commercial hybrids at two Texas locations, Weslaco and College Station. The early and intermediate hybrids chosen are primarily marketed in midwestern USA while the full‐season hybrids are primarily marketed in southeastern USA. Hybrids were evaluated by inoculating ears 6 to 10 d after midsilk with Aspergillus flavus NRRL 3357 using the silk channel technique and measuring aflatoxin in harvested grain using the VICAM Aflatest procedure. Across locations, full‐season hybrids had lower aflatoxin (mean = 777 ng g−1) levels than intermediate (mean = 1668 ng g−1) and early (mean = 1899 ng g−1) hybrids. There was an inverse correlation between silking date and aflatoxin levels at both locations (r = −0.59, P = 0.01 at College Station and r = −0.58, P = 0.01 at Weslaco). Early and intermediate hybrids had looser husk coverage than full‐season hybrids, a characteristic that was positively correlated with aflatoxin levels at both locations. At both locations, grain yield was lower with early and intermediate hybrids than with full‐season hybrids. Early maturation in hybrids was insufficient by itself to reduce aflatoxin contamination, but it should be re‐evaluated using early maturing hybrids that have good agronomic adaptation to these two Texas growing conditions.

Aflatoxin Accumulation in Maize Hybrids of Different Maturities

The incidence and severity of preharvest aflatoxin is greater under drought conditions, which commonly occur late in the growing season of south and central Texas. To determine if early maturation could be used as a means of disease escape, aflatoxin contamination was measured in early-, intermediate-, and full-season commercial hybrids at two Texas locations, Weslaco and College Station. The early and intermediate hybrids chosen are primarily marketed in midwestern USA while the full-season hybrids are primarily marketed in southeastern USA. Hybrids were evaluated by inoculating ears 6 to 10 d after midsilk with Aspergillus flavus NRRL 3357 using the silk channel technique and measuring aflatoxin in harvested grain using the VICAM Aflatest procedure. Across locations, full-season hybrids had lower aflatoxin (mean = 777 ng g−1) levels than intermediate (mean = 1668 ng g−1) and early (mean = 1899 ng g−1) hybrids. There was an inverse correlation between silking date and aflatoxin levels at both locations (r = −0.59, P = 0.01 at College Station and r = −0.58, P = 0.01 at Weslaco). Early and intermediate hybrids had looser husk coverage than full-season hybrids, a characteristic that was positively correlated with aflatoxin levels at both locations. At both locations, grain yield was lower with early and intermediate hybrids than with full-season hybrids. Early maturation in hybrids was insufficient by itself to reduce aflatoxin contamination, but it should be re-evaluated using early maturing hybrids that have good agronomic adaptation to these two Texas growing conditions.

Deficit irrigation impact on lycopene, soluble solids, firmness and yield of diploid and triploid watermelon in three distinct environments

SummaryWater conservation practices are critical for production and quality of watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] in southern regions of the USA. The objective of this experiment was to determine the effects of deficit irrigation and environment on lycopene content, total soluble solids, firmness, and yield of diploid and triploid watermelon. Irrigation rates were 1.0 evapotranspiration (ET), 0.75 ET, and 0.5 ET, which were calculated based on climatic parameters applied to the Penman-Monteith equation. Diploid cultivars were ‘Summer Flavor 710’ and ‘Summer Flavor 800’, and triploid cultivars were ‘Summer Sweet 5244’ and ‘Super Seedless 7187’. To investigate if there was a consistent response in cultivars across diverse environments, three studies were conducted in remote Texas locations: Uvalde in the Wintergarden, Weslaco in the Rio Grande Valley, and Lubbock in the High Plains. To isolate the environmental effects due to weather and soil type, all experiments used similar cultural strategies (plant spacing, subsurface drip irrigation, black plastic mulch, and containerized transplants), except for transplanting and harvesting dates. Deficit irrigation reduced total marketable yield by 36% at Uvalde, 30% at Lubbock, and 15% in Weslaco, increasing the yield of small fruits (<5 kg). Location and irrigation rates had major influences on yield of diploid and triploid watermelon. Soluble solids content increased with deficit irrigation at 0.5 ET rate in triploids, but not in diploids. Flesh firmness also increased in triploids compared to diploids. Fruit lycopene content increased with maturity (7 and 22 d after ripening) at all irrigation rates and cultivars. This work across three diverse Texas locations confirms that deficit irrigation directly reduced yield, but does not reduce lycopene development and fruit quality of triploid watermelon.

Resistance to the Mexican Rice Borer (Lepidoptera: Crambidae) Among Louisiana and Texas Sugarcane Cultivars

A 2-yr study to evaluate Louisiana and Texas sugarcane, Saccharum spp., cultivars for resistance to the Mexican rice borer, Eoreuma loftini (Dyar), was conducted in two locations in Texas, chosen for having different infestation levels. Criteria for assessment of resistance included percentage of bored internodes and adult emergence holes, the latter used to determine the relative impact of each cultivar on the potential areawide buildup or reduction of adult E. loftini populations. A recently released cultivar, HoCP 85-845, seemed to lose a portion of its resistance under heavy E. loftini infestation pressure, suggesting its value only in moderate-to-low infestation conditions. Cultivar CP 70-321 was the most resistant. Results indicated that cultivar LCP 85-384 was significantly (P < 0.05) more susceptible than NCo 310, traditionally the most susceptible cultivar commercially produced in Texas. In 2001, LCP 85-384, which now represents 85% of the production area in Louisiana, had the greatest moth production per hectare (17,052 ± 3,956) under the lower infestation pressure, significantly (P < 0.05) higher than HoCP 85–845 (3,038 ± 2,353). In a portion of the test at the high-infestation location, high levels of sodium and magnesium salt stress (15–30-cm soil depth) were associated with higher E. loftini damage in all cultivars except HoCP 91-555 and CP 70-321.

Survey of resistance to permethrin and diazinon and the use of a multiplex polymerase chain reaction assay to detect resistance alleles in the horn fly, Haematobia irritans irritans (L.).

A field survey was conducted in 2001 to evaluate resistance to pyrethroid and organophosphate (OP) insecticides on horn flies, Hematobia irritans irritans (L.), from seven ranches in the state of Tamaulipas, Mexico, and from three locations in central Texas. Filter papers impregnated with either technical permethrin or diazinon were used to measure the levels of resistance to pyrethroids and OPs. A multiplex polymerase chain reaction (PCR) assay was used on individual horn flies from these field populations to detect the presence of the kdr and super-kdr alleles associated with pyrethroid resistance, and a mutated alphaE7 esterase allele associated with OP resistance. Relative to a susceptible laboratory (Kerrville) strain, horn flies from Mexico exhibited 5.1- to 28.3-fold resistance to permethrin at the LC50, and 23.8- to 136-fold resistance at the LC90. Horn flies from Texas ranches exhibited only two- to five-fold resistance. All field populations of the horn fly were highly susceptible to diazinon, and no mutant alphaE7 esterase alleles were detected. The super-kdr allele was found only in a single fly from a ranch in Mexico. Results of PCR assays showed that the kdr allele was present at various frequencies in field populations of horn flies. A gender-related bias in distribution of kdr genotypes was found in horn flies from Mexico, but not in horn flies from Texas. The overall kdr allelic frequencies in horn flies from Mexico were 23.2-37.8% higher in females than in males. Regression analysis revealed a significant correlation between kdr allelic frequencies and the levels of knockdown resistance to permethrin among the horn fly populations studied. The results validate the role of the PCR-based molecular assay as a diagnostic tool in monitoring resistance to pyrethroids and also provide useful information on population genetics of horn fly resistance to pyrethroids and OPs.

Severe persistent orf in young goats.

Orf (contagious ecthyma) is a viral disease of small and wild ruminants, humans, and less frequently other species. In sheep and goats, the disease is characterized by the formation of vesiculo-proliferative lesions in the skin of lips and nostril. Here, a form of generalized orf in 16 goat kids from 2 different locations in west Texas is described. The disease was characterized by multifocal, severe, proliferative dermatitis that persisted from about 2 months of age until the goat kids were euthanized 3 months later. All affected goats were Boer or Boer crosses under 1 year of age. The mean immunoglobulin concentration in sera of affected goats was elevated compared with healthy control goats. Severe to moderate lymphadenomegaly of the nodes draining the areas of the skin affected with orf lesions was present in all 16 goat kids. Suppurative arthritis, chronic fibrinous pneumonia, and premature thymic involution were found in 3, 5, and 7 of the goat kids, respectively. The skin lesions of 3 goat kids were infested with larvae of the opportunistic black garbage fly (Ophira sp.). The orf virus was identified in skin lesions by isolation in Marbin-Darby ovine kidney cells, electron microscopy, and amplification of viral DNA by polymerase chain reaction. The orf virus was not detected in peripheral blood or lymph node mononuclear cells of any of the goats. Cross-neutralization experiments showed that an ovine orf virus antiserum raised in sheep was more effective in neutralizing a sheep orf virus isolate than a caprine orf virus isolate. The clinical and epidemiological characteristics of these orf cases may be the result of susceptibility factors within some individuals of the Boer breed of goats.

Imazethapyr Application Methods and Sequences for Imidazolinone-Tolerant Rice (Oryza sativa)1

Experiments were conducted at two locations in Texas during 2000 and 2001 to compare barnyardgrass, broadleaf signalgrass, and red rice control; rice tolerance; and grain yield after single and sequential applications of imazethapyr in imidazolinone-tolerant rice. Red rice and barnyardgrass control on a clay soil at Beaumont was at least 94% with imazethapyr at 70, 90, and 100 g ai/ha applied preplant incorporated (PPI) or preemergence (PRE) followed by (fb) at least 40 g/ha of imazethapyr applied early postemergence (EPOST). Broadleaf signalgrass control on a very fine sandy loam soil at Eagle Lake was at least 86% when imazethapyr was applied PPI or PRE fb EPOST applications of imazethapyr. Sequential postemergence applications at Beaumont resulted in at least 95% red rice and barnyardgrass control when 40 g/ha applied late postemergence followed any EPOST application. Sequential postemergence applications at Eagle Lake controlled broadleaf signalgrass 98% during both years. Imazethapyr applied postemergence injured rice 0 to 34% up to 12 d after treatment. Rice yield reductions were correlated to weed control and most likely were not associated with early-season rice injury.Nomenclature: Imazethapyr; imidazolinone; barnyardgrass, Echinochloa crus-galli (L.) Beauv. #3 ECHCG; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash # BRAPP; red rice, Oryza sativa L. # ORYSA; rice, Oryza sativa L. # ORYSA.Additional index words: CLEARFIELD* rice, Newpath.Abbreviations: EPOST, early postemergence; fb, followed by; LPOST, late postemergence; PD, panicle differentiation; PPI, preplant incorporated; PRE, preemergence.

Performance and Mapping of Leaf Rust Resistance Transferred to Wheat from Triticum timopheevii subsp. armeniacum

ABSTRACT Host plant resistance is an economical and environmentally sound method of control of leaf rust caused by the fungus Puccinia triticina, which is one of the most serious diseases of wheat (Triticum aestivum) worldwide. Wild relatives of wheat, including the tetraploid T. timopheevii subsp. armeniacum, represent an important source of genes for resistance to leaf rust. The objectives of this study were to (i) evaluate the performance of leaf rust resistance genes previously transferred to wheat from three accessions of T. timopheevii subsp. armeniacum, (ii) determine inheritance and allelic relationship of the new leaf rust resistance genes, and (iii) determine the genetic map location of one of the T. timopheevii subsp. armeniacum-derived genes using microsatellite markers. The leaf rust resistance gene transferred to hexaploid wheat from accession TA 28 of T. timopheevii subsp. armeniacum exhibited slightly different infection types (ITs) to diverse races of leaf rust in inoculated tests of seedlings compared with the gene transferred from TA 870 and TA 874. High ITs were exhibited when seedlings of all the germ plasm lines were inoculated with P. triticina races MBRL and PNMQ. However, low ITs were observed on adult plants of all lines having the T. timopheevii subsp. armeniacum-derived genes for resistance in the field at locations in Kansas and Texas. Analysis of crosses between resistant germ plasm lines showed that accessions TA 870 and TA 874 donated the same gene for resistance to leaf rust and TA 28 donated an independent resistance gene. The gene donated to germ plasm line KS96WGRC36 from TA 870 of T. timopheevii subsp. armeniacum was linked to microsatellite markers Xgwm382 (6.7 cM) and Xgdm87 (9.4 cM) on wheat chromosome arm 2B long. This new leaf rust resistance gene is designated Lr50. It is the first named gene for leaf rust resistance transferred from wild timopheevi wheat and is the only Lr gene located on the long arm of wheat homoeologous group 2 chromosomes.

Rural isolation and the availability of hospital services

This study empirically examines some important factors affecting the geographic distribution of hospitals. Using 1996 cross-sectional data on hospital locations in Texas, we employ a count-data methodology to estimate the impact of demand and rural isolation on the frequency of hospital service in a given geographical area. Using the model's estimates, we calculate the population thresholds needed to support a given frequency. Results suggest that population, population density, per capita income, and rural isolation are important factors in determining the number of hospitals in an area. Our methodology and results provide a means to inform and evaluate policy decisions regarding the designation of medically underserved areas.

Flufenacet and Metribuzin Combinations for Weed Control and Corn (Zea mays) Tolerance1

Field studies were conducted in 1999 and 2000 at seven locations in south Texas to evaluate flufenacet plus metribuzin for weed control and corn tolerance. Texas panicum control with flufenacet plus metribuzin was variable with less than 70% control in 1999 and greater than 75% control in 2000. Palmer amaranth and pitted morningglory control ranged from 41 to 100%. Corn stunting (4 to 13%) was noted in soils with greater than 75% sand. Corn yields with flufenacet and metribuzin combinations were increased up to 19% over the untreated check where stunting was not observed. Nomenclature: Flufenacet; metribuzin; Palmer amaranth, Amaranthus palmeri S. Wats. #3 AMAPA; pitted morningglory, Ipomoea lacunosa (L.) # IPOLA; Texas panicum, Panicum texanum Buckl. # PANTE; corn, Zea mays L. ‘AS986’, ‘Pioneer 3223’, ‘Pioneer 32K61’, ‘DK-668’. Additional index words: Corn tolerance, ivyleaf morningglory, weed management. Abbreviations: POST, postemergence; PRE, preemergence.

MISSISSIPPI COTTON YIELD MONITOR: THREE YEARS OF FIELD-TEST RESULTS

The Mississippi cotton yield monitor, which is based on an optical cotton-flow sensor comprised of emitters anddetectors in one unit that can be affixed to only one side of a pneumatic duct, has been under development at Mississippi StateUniversity since 1999. One prototype of the yield monitor was field tested that year in Mississippi. In 2000, three prototypeswere constructed and field tested in Texas, Georgia, and Mississippi on about 530 ha (1300 acre) of cotton. Different varietieswith large yield variations were harvested. In the Texas test, average absolute errors for two fields were 5.9% and 5.4%.Results from the Georgia test indicated an average absolute error of 5.7%. System reliability was tested in Mississippi on about445 of the total 530 ha (1100 out of 1300 acre) of cotton. Based on the 2000 results, a new version of the Mississippi cottonyield monitor was designed to include anti-stray-light and temperature-stabilization features. Five prototypes of the newversion were fabricated and field tested in 2001 on three cotton pickers and two cotton strippers at five locations in Georgia,Texas, and Mississippi. A total of 1230 ha (3000 acre) of cotton was harvested with the yield monitors from September toDecember of 2001. Results indicated that the average absolute errors of the system were 3.7% and 4.9% in two fields wheresystem accuracy was evaluated load by load. Considering all three years data, the average measurement error of theMississippi cotton yield monitor was less than 5%, and the latest prototype is improved over previous versions. Cotton yieldmaps have been created with data from all the field tests, and the maps realistically exhibit yield variations within fields, basedon the expectations of experienced producers and consultants. The tests also indicated that the system was reliable and easyto install, operate, and maintain.

Effect of the high-oleic trait on roasted peanut flavor in backcross-derived breeding lines.

The high-oleic trait of peanut (Arachis hypogaea L.) has been suggested to have a positive impact on the roasted peanut sensory attribute. A series of lines derived by backcrossing the high-oleic trait into several existing cultivars were compared with their parent cultivars at locations in Florida, Georgia, North Carolina, and Texas. Breeders grew their high-oleic lines and parents in three-replicate tests at one or two locations. The Florida high-oleic line F435-2-3-B-2-1-b4-B-B-3-b3-b3-1-B was grown at each location. The test included normal- and high-oleic variants of F435, GK 7, NC 7, NC 9, Sunrunner, Tamrun 96, and Tamspan 90. Sound-mature kernel samples were roasted, ground into paste, and evaluated by a sensory panel using a 14-point flavor intensity unit (fiu) scale. Background genotype had an effect (P < 0.01) on the heritable sensory attributes roasted peanut, sweet, and bitter. Oleate level had a positive effect on roasted peanut intensity, increasing it by 0.3 fiu averaged across all seven background genotypes. However, the magnitude of improvement varied across background genotypes. The high-oleic trait had no effect or increased the intensity of the roasted peanut attribute in each background genotype. The increase was greatest in Tamrun 96 (+0.6 fiu, P < 0.05) and Spanish genotypes Tamspan 90 (+0.4 fiu, P < 0.05) and F435 (+0.4 fiu, P < 0.10). A change of 0.5 fiu or more should be perceptible to consumers. Interaction between oleate level and background genotype was detected for sweet (P < 0.10) and bitter (P < 0.01) attributes. The trait had an increasing effect on the bitter attribute only in the background genotype of Tamspan 90 (+0.7 fiu, P < 0.01). There was a nonsignificant increase in bitterness in the other Spanish background genotype, F435. Changes in bitterness in runner- and Virginia-type backgrounds were close to zero. Incorporation of the high-oleic trait into peanut cultivars is likely to improve the intensity of the roasted peanut attribute, but it may also increase the bitter attribute in Spanish genotypes.

Aflatoxin Accumulation of White and Yellow Maize Inbreds in Diallel Crosses

ABSTRACTPreharvest aflatoxin (AF) contamination is one of the main limitations for corn (Zea mays L.) production in the southern USA causing enormous economic losses and posing a risk to animal and human health. The objectives of this study were (i) to evaluate and compare hybrids of new and selected potential sources of AF resistance for AF accumulation under field conditions, (ii) to identify the inbreds with the most consistent expression of resistance under different hybrid combinations and growing conditions; and (iii) to estimate combining abilities of white and yellow inbreds for aflatoxin accumulation and secondary traits. Two diallels among six local and exotic white and six yellow maize inbreds were evaluated at three locations in Texas. Inoculation with Aspergillus flavus Link:Fr. isolate NRRL 3357, either directly through the silk channel or as infested kernels on the soil surface, was effective in promoting AF accumulation in hybrids. White hybrids with low aflatoxin were CML269 × TxX24 and CML269 × CML176. CML269, CML176, and CML322 were the white inbreds with the lowest most consistent AF in hybrids and had the best GCA for aflatoxin resistance. Yellow hybrids with low AF were FR2128 × Mp715, Tx772 × Mp715, and Tx772 × CML326. Tx772 and FR2128 had the best GCA for reduced AF across locations or at specific locations. Inbreds CML326 and Tx772 had consistently low aflatoxin accumulation in hybrids across environments. AF content was correlated with husk cover, ear rot ratings, and insect damage. Exotic inbreds have genetic factors that can contribute to the reduction of aflatoxin contamination.

Tolerance of Virginia-Type Peanut to Different Application Timings of 2,4-DB

Abstract Field studies were conducted to determine the effects of 2,4-DB application timings on yield and market quality of virginia-type peanut. Trials were conducted at three locations in Texas and one location in North Carolina in 1997, 1998, and 1999. 2,4-DB at 0.45 kg ae/ha was applied 30, 45, 60, 90, and 120 d after planting (DAP). Additional timings included combinations of 30 DAP followed by (fb) 60, 90, or 120 DAP; 60 DAP fb 90 or 120 DAP; and 90 DAP fb 120 DAP. Peanut yield, market grade factors, and pod and seed weight were not influenced by various application timings of 2,4-DB.

Genetic Differentiation of Southeastern Boll Weevil and Thurberia Weevil Populations of &lt;I&gt;Anthonomus grandis&lt;/I&gt; (Coleoptera: Curculionidae) Using Mitochondrial DNA

The southeastern boll weevil, the Mexican boll weevil, and the thurberia weevil are considered to be morphologically similar but behaviorally different variants of the same species, Anthonomus grandis Boheman. A polymerase chain reaction (PCR)-amplified 9.2-kb section of the mitochondrial DNA was cleaved with restriction enzymes. RFLPs of weevils from three cotton growing locations in Texas and one in northeastern Mexico were compared with thurberia weevil from three sites in Arizona. Six haplotypes were observed in the Texas/Mexico collections and 12 haplotypes were found among the thurberia weevil. There were no shared haplotypes between these two groups. Polymorphism was observed within the weevil types. The three thurberia weevil locations exhibit some geographic isolation and exhibit differences in both the haplotypes present and the relative frequencies of the haplotypes. Only one haplotype was recovered at all three Arizona sites. The Texas/Mexico samples showed less genetic variability with the northern most site having the lowest polymorphism. 52/53 of these weevils appear to be genetically southeastern boll weevil. Two haplotypes were shared by all four of these populations and comprised 72% of the insects examined. The range of genetic distances between haplotypes was <0.001–0.022. The Mexican boll weevil was not explicitly examined; however, three individuals were discovered that appear to represent a genetically distinct third population. One was from Mexico and the other two were from a thurberia weevil site. These three individuals may represent the Mexican boll weevil. The results include apparent diagnostic restriction fragment differences between the thurberia weevil and the southeastern boll weevil that could be used to help determine whether future weevils found in Arizona or California cotton are thurberia weevil, southeastern boll weevil, or another population of weevils.

Redberry Juniper Canopy Cover Dynamics on Western Texas Rangelands

Knowledge of the rate woody plant canopy cover increases is essential for understanding the ecology of rangeland plant communities, determining the economic feasibility of brush management practices, and for scheduling initial and maintenance control practices. We determined rates of change in redberry juniper (Juniperus pinchotii Sudw.) canopy cover from the mid 1950s through the late 1990s at 5 locations in western Texas on rangeland that had been chained or grubbed for juniper control and on adjacent untreated areas. Juniper cover was estimated from aerial photographs by the line intercept method using a 10-X monocular lens with a vernier. Juniper cover increased at 0.35 +/- 0.06 percentage units year(-1) on untreated sites and at 1.01 +/- 0.07 percentage units year(-1) following chaining or grubbing. Juniper cover returned to pre-treatment levels in an average of 20 years (range 11 to 25) following chaining or grubbing. Herbage production on untreated rangeland was predicted to decline slowly (2.4 to 5.0 kg ha(-1) year(-1)) as juniper cover increased from 6 to 14% and rapidly (> 8 kg ha(-1) year(-1)) as juniper cover increased from 30 to 38%. Herbage production was predicted to decline at a constantly increasing rate following mechanical control of juniper, from < 2 kg ha(-1) year(-1) in year 1 to 23 kg ha(-1) year(-1) in year 29. Potential additional livestock carrying capacity due to juniper control would be under estimated by more than 40%, assuming forage production without treatment remained constant during the entire planning horizon of an economic analysis. To avoid significant reductions in livestock carrying capacity, redberry juniper control should be implemented before its canopy cover exceeds about 20%. DOI:10.2458/azu_jrm_v54i5_ueckert

Chain Diker Effects on Seeded Grass Establishment following Disk Chaining

Placing basins in rangeland seedbeds to capture rainfall has enhanced seeded grass establishment, but it has not been practical on debris-littered land following rootplowing for brush control. A disk chain tested previously will traverse land littered with debris or shrubs while tilling the soil for seedbed preparation. A chain diker is an implement designed to form 10-cm deep basins with a volume of 3.9 +/- 0.9 liters on tilled land. Combining the 2 implements provided tillage, land smoothing and basin formation in the soil with a single pass on debris littered land. Our 4-year study compared established grass densities on disk-chained seedbeds with and without chain diking at 5 locations in west Texas where land was rootplowed for honey mesquite (Prosopis glandulosa Torr. var. glandulosa) control. At 4 locations seedbeds were aerially seeded with 2 kg ha(-1) pure live seed (PLS) of WW Spar bluestem (Bothriochloa ischaemum (L.) Keng). At 1 location a mixture of 6 grasses, including Spar bluestem, was aerially seeded at 2.8 kg ha(-1) PLS. Evaluations were based on established grass densities at the end of the first growing season. At 3 locations, a seeding-before-diking treatment was included to simulate seed dropping from a seedbox mounted over the disk-chain's roller. In the Rolling Plains region of northwest Texas (4 sites), when growing-season rainfall was less than 400 mm, chain-diked seedbeds increased grass densities 2.6 times (P = 0.05) compared to non-diked seedbeds. When growing-season rainfall was greater than 500 mm, grass densities on diked seedbeds were similar to non-diked seedbeds. In the Trans-Pecos region of far-west Texas (1 site), where average growing-season rainfall is 337 mm, diked seedbeds produced 33% greater grass densities (P = 0.05) than non-diked seedbeds with rainfall of 552 mm. Densities of kleingrass (Panicum coloratum L.) and Spar bluestem were significantly greater in the diked seedbeds compared to non-diked seedbeds, and the other 4 grasses were not significantly influenced by seedbed methods. Grass densities were similar whether seeding after diking or before diking. Since long-term, growing-season rainfall has averaged below 500 mm between 65% to 87% of the time at these locations, our data suggests that it would be advantageous to include chain diking in combination with disk chaining for grass establishment on rootplowed land littered with brush debris. DOI:10.2458/azu_jrm_v54i2_wiedemann

S-Metolachlor Compared with Metolachlor on Yellow Nutsedge (Cyperus esculentus) and Peanut (Arachis hypogaea)1

S-metolachlor was compared with metolachlor at four field locations in Texas during the 1996 and 1997 growing seasons in terms of yellow nutsedge control, peanut injury, and peanut yield. S-metolachlor caused peanut injury comparable to metolachlor when either herbicide was applied preplant incorporated or preemergence. Yellow nutsedge control was similar and peanut yields were comparable with the two herbicides. At one location where yellow nutsedge failed to develop, the untreated check produced one of the highest yields.Nomenclature: Metolachlor; S-metolachlor; yellow nutsedge, Cyperus esculentus L. #3 CYPES; peanut, Arachis hypogaea L. ‘Florunner’, ‘AT-120’, ‘GK-7’.Additional index words: Groundnut, herbicide efficacy, peanut stunting.Abbreviations: POST, postemergence; PPI, preplant incorporated; PRE, preemergence.

Texas Driver Understanding of Abbreviations for Changeable Message Signs

Research was conducted as part of an ongoing project for the Texas Department of Transportation to evaluate the use of changeable message signs (CMSs) in Texas. The objective was to determine motorist understanding of abbreviations for use on CMSs. A human factors study was conducted in six locations in Texas. Participants were given a list of abbreviations and were asked to interpret the full words or phrases. The results identified 24 abbreviations that were understood at an acceptable level for use on CMSs in Texas; acceptability was based on a criterion of 85 percent or more of the participants’ correctly interpreting the word or phrase. Differences in study location comprehension levels were also examined. Twelve abbreviations were recommended for use only at particular locations on the basis of the varying comprehension levels among the six study locations. Abbreviations that were understood by less than 85 percent of the participants were not recommended for use in Texas.