Burleson County Research Articles

Genetic and Pathogenic Variability among Isolates of Sporisorium reilianum Causing Sorghum Head Smut.

Sporisorium reilianum, the causal agent of sorghum (Sorghum bicolor (L.) Moench) head smut, is present in most sorghum-producing regions. This seed replacement fungal disease can reduce yield by up to 80% in severely infected fields. Management of this disease can be challenging due to the appearance of different pathotypes within the pathogenic population. In this research, the genetic variability and pathogenicity of isolates collected from five Texas Counties was conducted. Due to the lack of available space, 21 out of 32 sequenced isolates were selected and evaluated for virulence patterns on the six sorghum differentials, Tx7078, BTx635, SC170-6-17 (TAM2571), SA281 (Early Hegari), Tx414, and BTx643. The results reveal the occurrence of a new pathotype, 1A, and four previously documented US pathotypes when the 21 isolates were evaluated for virulence patterns on the differentials. The most prevalent was pathotype 5, which was recovered from Brazos, Hidalgo, Nueces, and Willacy Counties, Texas. This pathotype was followed by 1A and 6 in frequency of recovery. Pathotype 4 was identified only from isolates collected from Hidalgo County, while pathotype 1 was from Burleson County, Texas. It appeared that the previous US head smut pathotypes (2 and 3) are no longer common, and the new pathotypes, 1A, 5, and 6, are now predominant. The phylogenetic tree constructed from the single-nucleotide polymorphism (SNP) data through the neighbor-joining method showed high genetic diversity among the tested isolates. Some of the diverse clades among the tested isolates were independent of their sampled locations. Notably, HS37, HS49, and HS65 formed a clade and were classified as 1A in the virulence study, while HS 61 and HS 66, which were collected from Nueces County, were grouped and identified as pathotype 5.

Holistic Machine-Learning Approach Recognizes Trouble Stages

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 204145, “Employing a Suite of Machine-Learning Algorithms in a Holistic Approach to Trouble Stage Recognition and Failure Diagnostics,” by Jessica Iriarte, SPE, Well Data Labs; Matthew McConnell, SPE, Hawkwood Energy; and Sam Hoda, SPE, Well Data Labs, et al. The paper has not been peer reviewed. The complete paper explores a holistic approach to characterizing trouble stages by applying automated event recognition of abnormal pressure increases and associating those events with formation and operational causes. This analysis of pressure increases provides insight into the potential causes of operational difficulties, and the related diagnostics can suggest improvements to future pump schedules. Improving how stages are pumped is profitable in both the short and the long term. Quantifying how design decisions ultimately affect operations can help decrease the frequency of operational problems and help realize these gains. Introduction The Cretaceous Eagle Ford Shale is the source rock for the Woodbine, Buda, and Austin Chalk. The wells included in this study are between the San Marcos Arch and the eastern edge of the East Texas Basin (Brazos and Burleson Counties). The Eagle Ford is similar to many other resource plays, such as the Marcellus, Utica, Barnett, Bakken, Haynesville, and Woodford shales. Among the many characteristics that make these plays similar is that each formation has provided stages with abnormal pressure behaviors (APBs).

Incidence of Zonate Leaf Spot on Sorghum Accessions Under Disease-Conducive Growing Conditions Burleson County, Texa

The frequent rains coupled with cooler than normal maximum temperatures in the early part of the 2021 growing season created conditions for severe outbreaks of zonate leaf spot infection on sorghum plants in the experimental plots at the Texas A&M AgriLife Farm, Burleson County, Texas. As a result, the incidence of zonate leaf spot was recorded for 68 accessions planted in one of the field trials. In this study, 13 sorghum accessions, including TAM428, BTx635, PI330255, PI534157, PI570841, PI609251, PI570726, and PI267588 were free of zonate leaf spot infection, indicating that they were highly resistant to the disease. The lines identified in this study may possess genes for resistance which can be useful in breeding programs for introgression of the resistant genes to elite or parental lines.

Correlations Among Grain Mold Severity, Seed Weight, and Germination Rate of Sorghum Association Panel Lines Inoculated With Alternaria alternata, Fusarium thapsinum, and Curvularia lunata

The sorghum association panel was evaluated for grain mold severity, seed weight, and germination rate. The 377 accessions were inoculated with Alternaria alternata alone, a mixture of A. alternata, Fusarium thapsinum, and Curvularia lunata, and untreated water-sprayed control during 2010, 2013-2015 growing seasons at the Texas AgriLife Research Farm, Burleson County, Texas. Each accession was evaluated at least twice. Across accessions, Spearman’s rank correlation was performed for non-parametric correlation analysis for grain mold severity, seed weight, and germination rate. There were significant negative correlations between grain mold severity with seed weight and germination rate for the individual treatment and when combined. A significant positive correlation between seed weight and germination rate was observed. The results indicated that higher grain mold severity reduces both sorghum seed weight and germination rate whether deliberately inoculated with fungal pathogens or naturally infected. It can be argued that correlations from this study were more robust due to a large number of accessions from all major sorghum races used and may represent the true association among the three parameters for this pathosystem. Thus, the use of grain mold-resistant lines, resulting in sound seeds and higher germination rates is recommended.

Young Field-grown Kiwifruit Plants’ Response to Early Autumn Frost Injury in Texas

Two-year-old, field-grown golden kiwifruit (Actinidia chinensis) and fuzzy kiwifruit (Actinidia deliciosa) plants were evaluated for injury following an early freeze event of −4.1 °C on 14 Nov. 2018 in Burleson County, TX. Plant material included seven cultivars: one seed-propagated [Sungold™ (ZESY002)] and three cutting-propagated golden kiwifruit (AU Golden Dragon, AU Golden Sunshine, CK03), and one seed-propagated (Hayward) and two cutting-propagated fuzzy kiwifruit (AU Authur and AU Fitzgerald). Observations were made 5 weeks after the frost event. Base trunk diameter (BD) and maximum trunk diameter damaged (MDD) provided a reference of plant size and crude measurement of damage intensity, as evident by presence of water-soaked necrotic and/or dehydrated tissue following the removal of a thin slice of periderm, vascular cambium, phloem, and xylem. Percent of base diameter damaged (PBDD) was calculated as MDD divided by BD and provided an assessment of damage, unbiased by plant size. Percent of shoot damaged (PSD) was visually evaluated as the percentage of entire shoot system exhibiting damage. In addition, presence of basal damage (DB) and basal cracking (CB) were recorded. A strong cultivar response was observed for BD, MDD, PBDD, and PSD. Mean cultivar values for PSD ranged from 79% and 19% for AU Authur and Sungold™ seedlings, respectively, which represented extremes among cultivars. Fuzzy kiwifruit exhibited greater injury (PBDD, PSD, DB, and CB) as compared with golden kiwifruit cultivars. Basal damage and basal cracking proved unique to fuzzy kiwifruit, as DB ranged from 0% in Sungold™ seedlings to 100% in fuzzy kiwifruit ‘AU Authur’ and ‘AU Fitzgerald’. In spite of having greater vigor, golden kiwifruit plants sustained less injury. Method of propagation had no effect on injury. PBDD and PSD proved to be reliable field assays for documenting injury, based on their strong correlation value (r = 0.92). Greater relative autumn frost tolerance of golden kiwifruit over fuzzy kiwifruit cultivars is previously unreported.

Genome-wide association study of grain mold resistance in sorghum association panel as affected by inoculation with Alternaria alternata alone and Alternaria alternata, Fusarium thapsinum, and Curvularia lunata combined

A total of 377 lines from Sorghum Association Panel (SAP) grouped into 10 subpopulations based on eight phenotypic traits, including flag leaf width, terminal branch length, flag leaf height, and flowering time and genetic data were evaluated for grain mold resistance by inoculating them with Alternaria alternata alone, a mixture of A. alternata, Fusarium thapsinum, and Curvularia lunata, and untreated water-sprayed control during 2010, 2013–2015 growing seasons at the Texas A&M AgriLife Research Farm, Burleson County, Texas. Each accession was evaluated at least twice. Eleven accessions exhibited grain mold severity ratings of 2 or less, indicating that they were resistant to highly resistant to the disease when challenged with A. alternata alone, 7 lines identified as such when inoculated with a mixture of A. alternata, F. thapsinum, and C. lunata, and 17 resistant lines were identified under the untreated control. Three lines PI533871, PI576130, and PI656036 exhibited resistant to highly resistant response to grain mold across treatments. When the 10 subpopulations were compared for disease response, accessions within subpopulation 4 had the lowest overall grain mold severity ratings, indicating that this subpopulation (zerazera/caudatum racial type) harbors genes that may contribute to grain mold resistance. A genome-wide association study with over 79,000 single-nucleotide polymorphic (SNP) loci from a publicly available genotype by sequencing dataset available for the (SAP) lines was conducted to identify genomic regions associated with grain mold resistance response based on the individual and combined treatments. In most cases, the top-scoring SNPs were mapped to the nearest or a nearby annotated gene with precedence for a role in host defense.

Screening Sorghum Accessions for Resistance against Anthracnose and Grain Mold through Inoculating with Pathogens

Aims: The aim of this study was to identify resistant accessions against pathogens, causing anthracnose and grain mold.
 Study Design: Study was laid out in a randomized complete block design with three replications. Data for anthracnose rating, grain mold severity, seed weight, and percent germination rate were analyzed using the command PROC GLM.
 Place and Duration of Study: The study was carried out at the Texas AgriLife Research Farm, Burleson County, Texas, in 2010, 2014, and 2015 growing seasons.
 Methodology: Forty-seven accessions were planted in 6 m rows 0.31 m spacing. Plants were inoculated by placing Colletotrichum sublineola colonized grain in the plant whorls 30 days after planting. Disease evaluation was initiated 30 days post-inoculation and thereafter on a weekly basis for three consecutive weeks. Grain mold experiment: Three treatments were used: 1) plants sprayed with A. alternata alone, 2) a mixture of A. alternata, F. thapsinum and C. lunata, 3) control plants sprayed with sterilized water and exposed to natural infection. At 50% bloom, three panicles per line within replication were inoculated for each treatment.
 Results: Eleven accessions, including PI641874, PI656070, PI656115, and PI534167 were consistently resistant when challenged with the anthracnose pathogen, C. sublineola. Accessions PI534047 and PI574455, exhibited resistance to moderately resistance grain mold response when challenged with the treatments. Seed weight, germination rate, and mycoflora analysis which are factors in determining grain mold resistance also were measured. Across the accessions, mean seed weight ranged from1.4 g to 4.3 g per 100 kernel and germination rate ranged from 26 to 87%. 
 Conclusion: The resistant accessions identified in this study can be used in breeding programs to develop anthracnose and grain mold resistance lines.

Species Composition and Abundance of the Natural Enemies of Sugarcane Aphid, Melanaphis sacchari (Zehnter) (Hemiptera: Aphididae), on Sorghum in Texas

The sugarcane aphid, Melanaphis sacchari (Zehntner), is an emergent sorghum pest in the United States. This study was designed to identify which natural enemy species are present in aphid populations in sorghum in Texas, and to track the seasonal population trends of the aphid and its natural enemies on sorghum hybrids that differ in susceptibility to the aphid. From 2015 through 2016, sugarcane aphid and its natural enemies were sampled weekly in plots of aphid-susceptible and partially aphid-resistant sorghum hybrids at two field sites in Nueces County and Burleson County, Texas. In 2015, aphids and natural enemies had greater peak abundance on the susceptible hybrid than on the resistant hybrid. Peak abundance of most natural enemies tended to lag behind that of aphids by one to two weeks. Natural enemy taxa observed at both field sites included two primary parasitoid wasp species (Hymenoptera: Aphelinidae: Aphelinus nigritus Howard stat. rev.; Braconidae: Lysiphlebus testaceipes (Cresson)), one species of hyperparasitoid (Hymenoptera: Encyrtidae), ten lady beetle species (Coleoptera: Coccinellidae) and three morphospecies of dusky lady beetle (Coccinellidae: Scymninae), three hoverfly species (Diptera: Syrphidae), five green lacewing species (Neuroptera: Chrysopidae), brown lacewings (Neuroptera: Hemerobiidae: Hemerobius), and minute pirate bugs (Hemiptera: Anthocoridae: Orius insidiosus (Say)). Aphelinus and Coccinellidae were the numerically dominant natural enemy groups in all sorghum hybrids, followed by Chrysopidae and Syrphidae. Aphids mummified by Aphelinus were hyperparasitized by Syrphophagus aphidivorus at a rate of approximately 90%. Natural enemy densities were similarly proportionate to aphid densities on both aphid-susceptible and aphid-resistant plants. Overall, the continuity of natural enemy species composition and population trends supports that these natural enemies responded positively to sugarcane aphid on sorghum.

‘The San Antonio River Doesn’t Start in San Antonio, It Now Starts in Burleson County’: Stakeholder Perspectives on a Groundwater Transfer Project in Central Texas

Water insecurity concerns drove San Antonio, Texas to pursue a controversial $3.4 billion groundwater transfer project from central Texas aquifers. The 228 km Vista Ridge Pipeline (VRP) would increase water supplies by 20%. Analysis through Q-Method revealed three social perspectives surrounding the VRP. Project Advocates offer particular views of urban water security, risk, and accountability. The creation of new hydro-social territories helps to explain Landowner Opposition, while Governance Failure offers a foundational criticism of the underlying assumptions and the institutional innovation of private-public partnership that advanced the VRP. Overall, our paper demonstrates that the VRP is differentiated according to views of risk, water law, and groundwater science. Policy deliberations on future urban water security should include these perspectives as a means to improve water governance, especially as policies and infrastructure for urban water security creates new hydro-social territories.

Integrating Geomechanical Data Optimizes Completions Design

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 191768, “Integrating Rock Properties and Fracture-Treatment Data To Optimize Completions Design,” by Eric Bruesewitz, SPE, Hawkwood Energy; Jessica Iriarte, SPE, Well Data Labs; Joel Mazza, SPE, Carrie Glaser, and Eric Marshall, Fracture ID; and Scott Brooks, Hawkwood Energy, prepared for the 2018 SPE Liquids-Rich Basins Conference—North America, Midland, Texas, USA, 5–6 September. The paper has not been peer reviewed. In the process of analyzing treatment responses that occur during hydraulic fracturing, several variances in treating pressure exist that are not readily explained by examining the surface pressures and pipe friction in isolation. These variances are also apparent when looking at bottomhole injectivity. This paper demonstrates how engineers can take advantage of their most-detailed completions and geomechanical data by identifying trends arising from past detailed treatment analyses. Introduction The Eagle Ford Shale was deposited in the Late Cretaceous Period in a marginal to open marine setting. The Lower Cretaceous part can be divided into two second-order transgressive/regressive cycles that have been labeled lower and upper Eagle Ford. The deposition of these units varies across the formation as a result of topography at the time of deposition. Therefore, operators in the Eagle Ford and other shale plays must account for changing stratigraphy and facies to locate horizontal wells properly for optimal perforation intervals. This study is based on integrated geomechanical data, metered high-frequency treatment data, and post-job reports. The data set used for this study corresponds to six wells completed in the Lower Bench of the Eagle Ford formation in Brazos and Burleson counties in Texas. Integration of completions, drilling, and geomechanical data has been analyzed before in the literature. Those authors observed an increase in pressure in several stages with higher Young’s modulus and lower gamma ray values, in which they were forced to pump an extra wellbore volume of clean fluid (sweep) to place the designed proppant volume. These sweeps accounted for more than 20,000 bbl of additional fluid pumped. The wells analyzed in this study presented data showing multiple examples of difficult-to-treat stages, in which unplanned sweeps had to be pumped and screenouts occurred frequently. Because the treating-pressure anomalies were correlated with mechanical rock properties in other unconventional plays, it was suspected that similar investigation may yield savings, efficiency, and productivity improvements in the Eagle Ford. Methodology The six wells of this study similarly consist of an approximately 7,600-ft lateral completed with 5.5-in. casing and approximately 150-ft stage lengths for a total of 283 stages analyzed. The fracture-treatment design consisted of proppant ramps of 100-mesh and 40/70 white sand placed primarily with slickwater. However, the completion design of four wells included cross-linked gel to place the highest proppant concentrations ranging between 3.0 and 4.0 lbm/gal. All six wells were recorded and processed for geomechanical properties such as Young’s modulus and Poisson’s ratio; a subsequent petromechanical model; and high-frequency fracture-treatment data (treating pressures, rates, and fluid and proppant volumes) and perforation data. The geo mechanical data gathered along the wellbore were divided and assigned to each stage, matching the measured depths to compare variables across data sets. Then, these data sets were standardized to a common format, screened for quality control, normalized, and analyzed with a data-management application.

Addendum Report: Additional Cultural Resources Investigations of the Vista Ridge Regional Water Supply Project in Burleson, Lee, Bastrop, Caldwell, Guadalupe, Comal and Bexar Counties, Texas

Addendum Report: Additional Cultural Resources Investigations of the Vista Ridge Regional Water Supply Project in Burleson, Lee, Bastrop, Caldwell, Guadalupe, Comal and Bexar Counties, Texas

1-Methylcyclopropene Effects on Field-Grown Cotton: Morphological Characteristics and Yield

Upland cotton (Gossypium hirsutum L.) is an important socioeconomic crop throughout most of the southern U.S. In Texas, cotton is the lead cash crop and its productivity is often limited by abiotic stress events such as drought and elevated ambient temperatures. The objective of this study was to assess the effects of 1-methylcyclopropene (1-MCP) applications triggered by canopy temperature and forecasted ambient temperatures on field-grown cotton plants. Yield and crop morphological responses to 1-MCP applications were investigated in field studies conducted during the summers of 2012 to 2014 at the Texas A&M University Field Laboratory in Burleson County, TX. Positive effects of 1-MCP were found for fruit retention in 2013 and 2014 for both irrigated and dryland studies; however, a negative impact was found in the 2012 irrigated study. By harvest, 1-MCP applications had no effect on final cotton yield or fiber quality parameters. Applications of 1-MCP affected some morphological characteristics of cotton plants; however, it did not improve crop yield.

Data Recovery Excavations at the Snakeskin Bluff Site (41GU177), Guadalupe County, Texas

Data Recovery Excavations at the Snakeskin Bluff Site (41GU177), Guadalupe County, Texas

Aboriginal Ceramic Wares from Sites in the Yegua Creek Drainage of the Brazos River Basin, East Central Texas

Sherds from aboriginally-made ceramic vessels have been recovered on sites dating after ca. 2000 years B.P. in the Yegua Creek drainage of the Brazos River basin in the Post Oak Savannah of Burleson, Lee, and Washington counties in east central Texas (Figure 1). These sherds are from several different wares, including sandy paste Goose Creek Plain sherds made by Mossy Grove peoples, ancestral Caddo tempered and decorated wares made in East Texas, bone-tempered sandy paste wares that may be representative of a local ceramic tradition, and bone-tempered sherds from Leon Plain vessels made by Central Texas Toyah phase peoples. None of the ceramic sherd assemblages from the 18 sites discussed herein are substantial, ranging only from 1-72 sherds per site (with an average of only 13.3 sherds per site), indicating that the use (much less their manufacture) of ceramic vessels by Post Oak Savannah aboriginal peoples was not of much significance in their way of life, but may signify interaction, trade, and exchange between them and other cultures, such as the Caddo, inland and coastal Mossy Grove, and Toyah phase peoples that relied on ceramic vessel manufacture and use as key parts of their subsistence pursuits. It is likely that the benefits of trade (ceramics being just one of the items that was being traded) between these different peoples was to help establish cooperative alliances, and reduce competition and violence in the region, and such alliances were established and maintained by aboriginal peoples over a long period of time in the region.

1-Methylcyclopropene Effects on Field-Grown Cotton: Physiological Characteristics

Cotton (Gossypium hirsutum L.) is the lead cash crop in Texas, and its productivity is often challenged by stressful environmental conditions such as high temperatures and sub-optimal water supply. The objective of this investigation was to assess the impact of 1-methylcyclopropene (1-MCP) applications triggered by canopy temperature and forecasted ambient temperatures on field-grown cotton plants. Physiological responses to 1-MCP applications were investigated in field studies conducted during the summers of 2012-2014 at the Texas A&M University Field Laboratory in Burleson County, TX. During all three growing seasons, more than 65% of the days reached temperatures above 28 °C, which indicated great potential for high temperature stress. Daily plant canopy temperature, net photosynthesis, transpiration, and photosystem II quantum yield were affected by 1-MCP treatment when plants were irrigated, but not under dryland conditions. Positive effects of 1-MCP were found for fruit retention in 2013 and 2014, for both irrigated and dryland studies, although a negative impact was found in the 2012 irrigated study. Applications of 1-MCP affected physiological characteristics; however, it did not affect crop yield.

First Report of Leaf Spot of Barley Caused by Drechslera gigantea in the United States

In December 2016 in Texas, extensive leaf spots (50% incidence with 2 to 8% leaf area affected) occurred on an experimental trial of barley (Hordeum secale var. ‘Wintmalt’) in Burleson county. The leaf spots were oval to elongated, 5 to 15 mm long, with a white to light brown center and a dark brown margin. Dematiaceous conidia 150 to 550 μm long × 15 to 18 μm wide with 3 to 12 septa, borne singly on unbranched conidiophores were observed in these lesions. Conidia had bipolar germination with multiple germ tubes. These features were consistent with the description of Drechslera gigantea (Drechsler 1923). Leaf pieces were placed in 10% NaOCl for 30 seconds, washed twice with sterile, distilled water and immediately blotted dry with a paper towel. The margins of lesions (2 mm2) were excised with a scalpel, placed onto water agar with streptomycin (WA), and incubated at 25oC. Dematiaceous mycelia were consistently isolated from plated lesions. Sporulation did not occur on V8 agar transfers, but did occur on ...

Cultural Resources Investigations of the Vista Ridge Regional Water Supply Project in Burleson, Lee, Bastrop, Caldwell, Guadalupe, Comal and Bexar Counties, Texas

On behalf of VRRSP Consultants, LLC and Central Texas Regional Water Supply Corporation (CTRWSC), SWCA Environmental Consultants (SWCA) conducted cultural resources investigations of the Vista Ridge Regional Water Supply (Vista Ridge) Project in Burleson, Lee, Bastrop, Caldwell, Guadalupe, Comal, and Bexar Counties. The work will involve installation of a 139.45-mile-long, 60-inch-diameter water pipeline from northcentral San Antonio, Bexar County, Texas, to Deanville, Burleson County, Texas. The report details the findings of investigations from June 2015 to December 2015, on the alignment dated December 8, 2015 (December 8th). The Vista Ridge Project is subject to review under Section 106 of the National Historic Preservation Act (54 USC 306108) and its implementing regulations (36 CFR 800), in anticipation of a Nationwide Permit 12 from the U.S. Army Corps of Engineers in accordance with Section 404 of the Clean Water Act. In addition, the work is subject to compliance with the Antiquities Code of Texas under Permit Number 7295, as the Vista Ridge Project will be ultimately owned by a political subdivision of the State of Texas. The cultural resources investigations included a background review and intensive field survey. The background review identified previous investigations, recorded archaeological sites, National Register of Historic Places (NRHP) properties, cemeteries, standing structures, and other known cultural resources within a 0.50-mile radius of the project area. The field investigations conducted from June 2015 through December 2015 assessed all accessible portions of the proposed December 8th alignment as of December 25, 2015. Approximately 101.8 miles of the 139.45-mile alignment has been surveyed. Approximately 24.42 miles were not surveyed based on the results of the background review and extensive disturbances as confirmed by vehicular survey. The remaining 13.23 miles that require survey were either unavailable due to landowner restrictions or part of a newly adopted reroute. SWCA also surveyed additional mileage, which includes rerouted areas that are no longer part of the December 8th alignment. The inventory identified 59 cultural resources, including 52 archaeological sites and seven isolated finds. In addition to newly recorded resources, two previously recorded archaeological sites were revisited, and two cemeteries were documented. Of the 52 newly recorded archaeological sites, seven are recommended for further work or avoidance. Of the two revisited archeological sites, one is recommended for further work or avoidance within the project area. Avoidance is recommended for both documented cemeteries. The resources with undetermined eligibility require additional testing or other avenues of research before SWCA can make a firm recommendation about their eligibility for nomination to the NRHP and designation as State Antiquities Landmarks (SALs). As part of a management strategy, the resources with undetermined eligibility may also be avoided by reroute or boring beneath. The remaining 45 cultural resources are recommended not eligible for inclusion to the NRHP or for designation as SALs and no further cultural resources investigations or avoidance strategies are recommended.

Reaction of Sorghum Lines to Zonate Leaf Spot and Rough Leaf Spot

Abundant, frequent rains along with humid and cloudy conditions during the early part of the 2015 growing season provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson County, near College Station, Texas. This afforded the opportunity to evaluate these lines for reaction to these diseases, which normally occur at trace levels in this area. Out of 181 sorghum lines, including a subset of the sorghum association panel, a total of 13 lines, including Dorado, Sureno, PI576434, PI656005, PI656034, PI656075, PI656024, and PI598070, were resistant to both diseases. These lines could be used in breeding programs to introgress the genes for resistance to both diseases into other adapted lines. Accepted for publication 8 December 2015. Published 14 December 2015.

A Multiyear Study on Seasonal Flight Activity Based on Captures of Southern Green Stink Bug (Hemiptera: Pentatomidae) in Blacklight Traps in Central Texas

The southern green stink bug, Nezara viridula (L.)(Hemiptera: Pentatomidae), is cosmopolitan in distribution and feeds on many cultivated plants. On cotton, it reduces yield and transmits fungal and bacterial pathogens that result in necrosis of the locule and boll rotting. Objectives of this study were to determine the seasonal flight activity and to assess numerical changes in the season-long captures of N. viridula in blacklight traps. Traps were established in a commercial farmscape where cotton and corn were the predominant crops. Minor crops grown in the area were milo, soybean, pecan, and watermelon. Study areas included four to five locations during each year from 2003 to 2011 in Burleson County of Central Texas. Frequency distribution of seasonal counts of N. viridula conformed to a clumped dispersion pattern when analyzed by Taylor’s Power Law and negative binomial distribution as probability models. Counts transformed by a power law function, x0.165, adequately uncoupled the mean and the variance of the data better than those transformed by log transformation. Significantly and consistently, more females than males were captured in traps. Peak captures of N. viridula in traps generally occurred in August. August counts of the insect declined precipitously from a monthly mean of 177 in 2003 to near zero in 2011. Results of this study demonstrate that blacklight traps are a useful sampling tool for determining N. viridula population numbers and to assess their seasonal flight activity in production agriculture.

Effect of an Upper Temperature Threshold on Heat Unit Calculations, Defoliation Timing, Lint Yield, and Fiber Quality in Cotton

In cotton production, delaying defoliation exposes open bolls to rainfall, reducing lint yield and fiber quality. However, premature defoliation has detrimental effects on both yield and quality. Currently, one management strategy for defoliation is based on heat-unit (HU) accumulation after physiological cutout or five nodes above white flower (NAWF = 5). Results have been inconsistent across environments when utilizing HU accumulation; therefore, adoption of this method has been limited. Studies were conducted in the Brazos River bottom and upper Texas Gulf Coast to identify an upper temperature threshold (UTT) for calculating degree days for defoliation timing. Experimental design was a split-plot with main plots of temperature thresholds (32°C, 35°C, and no upper limit) and subplots of HU timings (361, 417, 472, 528, and 583) accumulated from cutout. Utilizing an UTT to calculate daily HU failed to explain differences in the optimum time to defoliate based on accumulated HU; however, accumulated HU had an impact on defoliation timing. Comparison of locations showed that maximum lint yield was obtained at 472 HU and 52% open boll in Wharton County versus a maximum of 528 HU and 62% open boll for Burleson County. Employing the NACB = 4 method to time defoliation at both locations would have resulted in premature application of harvest aids and reduced lint yields. There were no differences in adjusted gross income values at Wharton County among the 417, 472, 528, and 583 HU treatments. For Burleson County, adjusted gross income peaked in value at 528 HU.