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In arid and semi-arid climates, water scarcity and nutrient availability are major constraints for food production. Excess fertilization to make up for the limited nutrient availability in dry soils leads to nitrogen runoff and groundwater contamination. Reducing nitrogen leaching into surface water while providing adequate nutrition remains a major challenge. Superabsorbent polymers (SAPs) can reduce water loss and improve nutrient retention and therefore minimize leaching and increase crop yields. SAPs are made from petroleum or natural products, but plant-based SAPs have been gaining popularity because they have fewer long-term effects on the environment. However, there is little known about how SAPs made from cornstarch effect plant growth and production in tomatoes. So, we evaluated total nitrogen and water retention in SAP-treated soils and evaluated their effects on growth and development of tomatoes (Solanum lycopersicum). Soils were amended with different rates of cornstarch-based SAP (i.e., 0 kg SAP, 0 kg SAP+N, 0.5 kg SAP+N, 1 kg SAP+N, 1.5 kg SAP+N, and 2 kg SAP+N). Results indicate that the mean volume of water and nitrates retained in the soils amended with cornstarch-based SAPs increased with increasing rate of SAP. The treatment containing the highest dose (i.e., 2 kg SAP) decreased the amount of leachate and nitrates from soil 79.34% and 93.11% at 3 days after fertilization (DAF) and 78.84% and 81.58% at 9 DAF in comparison with the soil-only and fertilizer-only treatments, respectively. The results also indicate cornstarch-based SAP significantly improved plant growth and yield parameters compared with the treatments without SAP. Furthermore, the greatest number of leaves, flowers, fruits, and dry matter production were found in the 1-kg SAP treatment. Therefore, application of cornstarch-based SAPs can improve tomato production in times of drought stress by retaining more water and nutrients in the active rooting zone and can reduce environmental pollution by reducing nitrogen runoff.

The use of distiller’s grains (DG) in beef cattle finishing diets is a common practice. However, the effects of supplemental fat on performance and nutrient losses of cattle fed diets containing DG are not known. Therefore, we fed 398 crossbred yearling heifers (initial BW = 373.5 kg) for 106 d to determine the effects of dietary fat concentration and sorghum-based wet distiller’s grains with solubles (SWDGS) on performance, carcass characteristics, and nutrient losses of finishing cattle. Treatments included two 92% concentrate, steam-flaked corn (SFC)-based diets with 0% or 3% added fat from yellow grease and 3 SFC-based diets with 15% SWDGS (DM basis) that contained either 0%, 1.5%, or 3% added fat (8 pens per treatment) in a randomized block design. Overall DMI and ADG were 5% to 6% greater (P < 0.01) for heifers fed 15% SWDGS than for those fed 0% SWDGS. Among heifers fed 15% SWDGS, DMI was greatest (P = 0.04; quadratic effect) and ADG tended (P = 0.12; quadratic effect) to be greatest for heifers fed 1.5% fat. The ADG:DMI did not differ between 0% SWDGS with 0% or 3% fat, and was not altered by replacing a portion of SFC with SWDGS (P > 0.36). However, ADG:DMI tended to increase as more fat was added to diets with 15% SWDGS (P = 0.06). Average hot carcass weight (HCW) was 5 kg greater (P = 0.05) when SWDGS was fed, but HCW tended to be greatest for heifers fed 15% SWDGS with 1.5% fat (P = 0.09, quadratic effect). Heifers fed 0% SWDGS with 0% fat tended to have a lower marbling score, less rib fat, lower average yield grade (P < 0.08), and more (P < 0.01) yield grade 1 carcasses than heifers fed 0% SWDGS with 3% fat. Averaged across fat levels, heifers fed 15% SWDGS had more rib fat and a higher yield grade (P < 0.03) than heifers fed 0% SWDGS. Feeding 15% SWDGS did not alter carcass quality grade distribution compared to feeding 0% SWDGS, but 15% SWDGS produced fewer yield grade 3 carcasses (P = 0.03) than 0% SWDGS. The calculated NEg of SWDGS (1.36 Mcal/kg) was 91% of the tabular value for dry rolled corn (1.50 Mcal/kg) and 84% of the tabular value for SFC (1.62 Mcal/kg). Nitrogen intake, and N excretion were greater (P < 0.05) in heifers fed 15% SWDGS than in heifers fed the 0% SWDGS diets, but N loss as a % of N intake was less (P < 0.05). Our results suggest adding 1.5% fat to diets containing 15% SWDGS may improve beef cattle performance; however, feeding logistics need to be considered when pricing wet DG.

White-tailed deer (Odocoileus virginianus) are a host for cattle fever ticks (Rhipicephalus (Boophilus) sp.), which are vectors of the pathogens causing bovine babesiosis and anaplasmosis in cattle. Tick eradication efforts focused on cattle along the U.S.-Mexico border are high priority and the potential role of white-tailed deer in compromising these efforts is of great concern. We developed a spatially-explicit, individual-based model to investigate the interactions of white-tailed deer, climate variation, and habitat heterogeneity on the efficacy of three standard tick eradication protocols: the application of acaricides to cattle every two weeks for (1) nine or (2) 12 consecutive months, or (3) the removal of cattle (“pasture vacation”) for 12 consecutive months. We simulated the application of each of these eradication methods during each of three different annual temporal weather profiles for temperature, saturation deficit, and precipitation. Each of the methods suppressed the number of host-seeking larvae in the system to near zero. However, some host-seeking larvae remained, and white-tailed deer remained infested throughout the treatment period. Within 30–60 days after the termination of each treatment, tick infestations began to increase, and within 2 years after the initiation of each treatment, populations of host-seeking larvae had increased to pretreatment levels. Differences in treatment efficacy and tick population recovery rates were influenced by (1) the level of pre-treatment infestation, (2) weather conditions during the treatment year, and (3) weather conditions during the post-treatment recovery period. Treatment efficacy and tick population recovery also were influenced by the habitat heterogeneity since cattle and white-tailed deer have different habitat preferences. During treatment periods, white-tailed deer participated in creating tick refugia by dispersing engorged female ticks into, and collecting host-seeking larvae from, habitats favorable for the survival and development of off-host life stages. These refugia facilitated the recrudescence of infestations following the termination of treatment periods. Future applications to assess tick-host-landscape interactions and to consider alternative tick suppression tactics in integrated tick eradication systems are discussed.

A rise in cotton boll rot in south Texas has been generally associated with increased yield losses. Here, we measured boll rot incidence during two growing seasons (2011 and 2012) at a south Texas (Kleberg County) research farm Variety Trial and in producer fields. The Variety Trial was conducted to compare boll rot susceptibility between five current cultivars. The commercial fields surveyed were located along the Coastal Bend (Wharton County) and Rio Grande Valley regions (Cameron and Willacy Counties). Bolls with evidence of external damage potentially inflicted by piercing-sucking insect vectors were dissected for disease detection and plated for microorganism isolation and characterization. Microbial isolates were putatively identified based on standard fatty acid methyl ester profile analysis. In the Variety Trial, the highest incidence of disease occurred in July for both growing seasons, and significant differences in susceptibility to boll rot between cultivars were determined (P < 0.05). The highest boll disease incidence was 28% in August 2012 for the Coastal Bend region and also 28% but in June 2011 in the Rio Grande Valley. Bacillus species were predominately isolated and associated with boll rot for all the fields studied over the 2 year period. This is the first report to directly study the occurrence of boll rot in south Texas and associate Bacillus spp. as a potential and prevalent causative agent(s).

Subtropical and tropical climates are becoming more vulnerable to drought and salinity problems. Of the crops produced in these climates, citrus is especially sensitive to increasing salinity. In times of water scarcity and periodic drought alternative water sources that may be lower in quality may be required for irrigation, leading to reduced yield unless a mechanism of increasing salinity tolerance is found. The salinity tolerance of citrus rootstocks differs depending on species and cultivar in their ability to exclude or sequester toxic ions. Identifying rootstocks that are more salt tolerant is important to citrus production in susceptible areas. ‘Olinda’ Valencia trees budded to three rootstocks (sour orange [SO], C22, and C146) and the ungrafted rootstocks were subjected to 6 months of saline irrigation. Simulated brackish water at 1, 3, 5, and 10 dS m −1 along with a 0 dS m −1 control were used to irrigate trees over the course of the study. Throughout this time period chlorophyll fluorescence, stomatal conductance, electrolyte leakage, and SPAD were measured to identify how trees responded to different levels of salinity stress. Chlorophyll fluorescence, stomatal control, and SPAD decreased with increased salinity, while electrolyte leakage increased. These responses were more pronounced in grafted trees than ungrafted trees. C22 and C146 rootstocks showed more tolerance to increases in salinity than the SO rootstocks. The ‘Olinda’ Valencia scion reduces rootstock tolerance to salinity, however, trees grafted to the C22 and C146 rootstocks showed more salinity tolerance than those grafted to SO rootstocks. This study emphasizes that both rootstock and scion should be considered when selecting trees for saline conditions.

White-tailed deer (Odocoileus virginianus) serve as a host for cattle fever ticks (Rhipicephalus [Boophilus] microplus and Rhipicephalus [Boophilus] annulatus; CFTs); therefore, deer are a concern for CFT control programs in southern Texas, US. Systemic (oral delivery of ivermectin) and topical (permethrin on pelage) treatment devices have been developed for white-tailed deer; however, the efficacy of these treatment options has not been determined for CFTs in southern Texas. Our objectives were to evaluate the effectiveness of CFT treatment strategies by 1) measuring exposure rates of deer to the acaricides permethrin and ivermectin, 2) determining the relationship between CFTs on deer and exposure to the acaricides, and 3) determining if photos from remote cameras at medicated bait sites can be used as a measure of acaricide treatment. We captured 327 deer at four sites in southern Texas. Deer visitation to medicated bait sites was monitored using remote cameras from March 2010 to February 2012. There was no relationship between the presence of permethrin and the probability of being infested with CFTs (P≥0.336). The probability of infestation with CFTs decreased as serum ivermectin levels increased for male (n=18, P=0.098) and female (n=33, P

Non-native plants have invaded nearly all ecosystems and represent a major component of global ecological change. Plant invasions frequently change the composition and structure of vegetation communities, which can alter animal communities and ecosystem processes. We reviewed 87 articles published in the peer-reviewed literature to evaluate responses of arthropod communities and functional groups to non-native invasive plants. Total abundance of arthropods decreased in 62% of studies and increased in 15%. Taxonomic richness decreased in 48% of studies and increased in 13%. Herbivorous arthropods decreased in response to plant invasions in 48% of studies and increased in 17%, likely due to direct effects of decreased plant diversity. Predaceous arthropods decreased in response to invasive plants in 44% of studies, which may reflect indirect effects due to reductions in prey. Twenty-two percent of studies documented increases in predators, which may reflect changes in vegetation structure that improved mobility, survival, or web-building for these species. Detritivores increased in 67% of studies, likely in response to increased litter and decaying vegetation; no studies documented decreased abundance in this functional group. Although many researchers have examined effects of plant invasions on arthropods, sizeable information gaps remain, specifically regarding how invasive plants influence habitat and dietary requirements. Beyond this, the ability to predict changes in arthropod populations and communities associated with plant invasions could be improved by adopting a more functional and mechanistic approach. Understanding responses of arthropods to invasive plants will critically inform conservation of virtually all biodiversity and ecological processes because so many organisms depend on arthropods as prey or for their functional roles, including pollination, seed dispersal, and decomposition. Given their short generation times and ability to respond rapidly to ecological change, arthropods may be ideal targets for restoration and conservation activities.

As population and agricultural pressure on high quality fresh water resources increases, it becomes more important to identify rootstocks and production techniques that allow the usage of lower quality water in irrigated agriculture. Water of 0, 1, 3, 5 and 10 dS m −1 salinity was applied to grafted (with Olinda Valencia ( Citrus sinensis var. Olinda) scion) and ungrafted sour orange ( Citrus aurantium L.), C22, and C146 ( Citrus sunki Hort. Ex Tan. × Poncirus trifoliata L. Raf. ‘Swingle’) trees to evaluate the effect of grafting and rootstock variety on salinity tolerance. Grafted rootstocks had a lower survival rate at higher salinity concentration than ungrafted trees and effects were dependent upon tree variety. Height growth rate and standing leaf area of grafted citrus trees declined with increased salinity concentrations while the response of ungrafted and grafted citrus trees was variety dependent. Mortality increased and standing leaf area decreased with increasing tissue Na + and Cl − concentrations. Mortality in response to salinity was greater in grafted rootstocks than mortality of ungrafted trees. Overall, C22 and C146 rootstocks and ungrafted trees were found to be more tolerant of saline conditions than grafted SO rootstock or ungrafted SO trees.

Zebra chip, a new and economically important disease of potato, Solanum tuberosum L., in the United States, Mexico, Guatemala, Honduras, Nicaragua, and New Zealand has caused millions of dollars in loss to the potato industry. The disease is associated with the bacterium “Candidatus Liberibacter solanacearum” transmitted to potato by the potato psyllid, Bactericera cockerelli (Sulc). Since its initial U.S. appearance in southern Texas in 2000, zebra chip has caused serious damage to potato production in the state, often leading to abandonment of entire fields. A study at Weslaco assessed the impact of potato planting time on incidence of zebra chip in the Lower Rio Grande Valley of Texas. Non-treated experimental potato plots were planted in mid-December to midFebruary for 4 years, and incidence of zebra chip was estimated at harvest each potato-growing season. Results showed that, in the Lower Rio Grande Valley, potatoes planted early were more affected by zebra chip than were those planted lat...

Ammonia emissions from cattle feedlots pose the potential to react with other compounds such as oxides of nitrogen and sulfur, which lead to detrimental environmental effects. Ambient ammonia (NH3) concentrations were measured continuously at a beef cattle feedyard for 12 months beginning in March 2007. Concentrations were measured every 5 min, 24 hours per day, at a sample intake height of 3.3 m using a chemiluminescence analyzer. On-site weather data were collected concurrently. Modeled emissions of NH3 were compared with the mass balance of N for the feedyard. Mean annual NH3 concentrations were 0.57 ppm, with a monthly average low of 0.37 ppm in December 2007 and a monthly average high of 0.77 ppm in August 2007. Flux densities were calculated using a backward Lagrangian stochastic model (WindTrax 2.0.7.8). Mean annual flux density was 70.7 µg m-2 s-1 (2.2 kg m-2 year-1). Mean monthly flux density ranged from 42.7 to 123.1 µg m-2 s-1 (0.11 to 0.32 kg m-2 month-1) in November and April 2007, respectively. Both concentration and flux density had a diel distribution with minima during the nighttime hours and maxima during the early afternoon. On an annual basis, 48.8% of fed N was volatilized as NH3. The inverse modeled daily ammonia production per head was 85.3 g NH3-N (head fed)-1 d-1.

Odor is a growing concern at concentrated animal feeding operations as residential houses encroach upon rural areas once occupied only by agriculture. A research project was conducted to determine baseline ambient odor characteristics at large open-lot beef cattle feedyards and to develop a better understanding of when and why odors occur at feedyards. Ambient odor samples were collected two to four times per month over a 12-month period in 2002-2003 at three large commercial open-lot beef cattle feedyards in the Texas panhandle. Ambient odor samples were collected upwind of the feedyard, downwind of the pens, and downwind of the runoff storage pond. Odor samples were also collected on five separate days covering four months in 2004 from a surface isolation flux chamber to estimate odor emission rates from the feedyard surface. All odor samples were collected in 10 L Tedlar bags and analyzed with trained human odor panelists for odor concentration (detection threshold, DT) by dynamic dilution forced-choice olfactometry, intensity by reference scaling, and hedonic tone. Manure moisture content and weather data were collected on-site at each of the feedyards. At two of the feedyards, mean DTs downwind of the pens and storage pond were statistically similar to upwind DTs, ranging from 33 to 45 OU m-3. At the third feedyard, mean DTs downwind of the pens (69 OU m-3) and pond (124 OU m-3) were statistically higher than the mean upwind DT (36 OU m-3) (p < 0.05). Odor emission rates ranged from 0.3 to 3.2 OU m-2 s-1 during a period when downwind DTs ranged from 17 to 132 OU m-3. A number of elevated DTs were explained by elevated manure moisture contents from recent precipitation. These results demonstrate that odor production from open-lot beef cattle feedyards is a complex phenomenon that depends at least partially on weather conditions. Thus, odor prediction and control will likely be difficult at these facilities.

Twenty-eight transgenic maize hybrids containing the Bacillus thuringiensis (Bt) endotoxin and several of their non-Bt isolines were evaluated for control of the southwestern corn borer, Diatraea grandiosella Dyar, the European corn borer, Ostrinia nubilalis (Hubner), and the corn earworm (CEW), Heliocoverpa zea (Boddie) in the shank and ear. The Bt hybrids represented four events (Mon810, Bt11, 176, and CBH354) from seven seed companies. The maize hybrids were grown in four locations that ranged from the northern to southern length of the Texas Panhandle. A semi-arid environment with hot days-cool nights and

Twenty-eight transgenic maize hybrids producing the Bacillus thuringiensis (Bt) endotoxin (Cry1A(b) or Cry9c) and several of their non-Bt isolines were evaluated for control of the southwestern corn borer, Diatraea grandiosella Dyar, and the European corn borer, Ostrinia nubilalis (Hubner). The Bt hybrids represented four events (Mon810 [Cry1A(b)], Bt11 [Cry1A(b)], 176 [Cry1A(b)], and CBH354 [Cry9c]) from seven seed companies. Maize hybrids were grown in four locations ranging from the northern to the southern Texas Panhandle, a semi-arid environment with hot days, cool nights and

In the United States, the generally non-pathogenic trypanosome of cattle is designated Trypanosoma (Megatrypanum) theileri and is distinguished morphologically from Trypanosoma (M.) cervi, a trypanosome originally described in mule deer and elk. Phylogenetic studies of the Megatrypanum trypanosomes using various molecular markers reveal two lineages, designated TthI and TthII, with several genotypes within each. However, to date there is very limited genetic data for T. theileri, and none for the Megatrypanum trypanosomes found in wild ungulates, in the U.S. In this study U.S. isolates from cattle (Bos taurus), white-tailed deer (Odocoileus virginianus) (WTD), and elk (Cervus elaphus canadensis) were compared by ribosomal DNA (rDNA) sequence analysis and their incidence in cattle and WTD in south Texas counties was investigated. Phylogenetic analyses showed clear separation of the bovine and cervine trypanosomes. Both lineages I and II were represented in the U.S. cattle and WTD parasites. Lineage I cattle isolates were of a previously described genotype, whereas WTD and elk isolates were of two new genotypes distinct from the cattle trypanosomes. The cattle isolate of lineage II was of a previously reported genotype and was divergent from the WTD isolate, which was of a new genotype. In La Salle, Starr, Webb, and Zapata counties in south Texas a total of 51.8% of white-tailed deer were positive for trypanosomes by 18S rDNA PCR. Of the cattle screened in Webb County, 35.4% were positive. Drought conditions prevailing in south Texas when the animals were screened suggest the possibility of a vector for Trypanosoma other than the ked (Lipoptena mazamae) and tabanid flies (Tabanus spp. and Haematopota spp.).

The ticks Rhipicephalus (Boophilus) annulatus and R. (B.) microplus, commonly known as cattle and southern cattle tick, respectively, impede the development and sustainability of livestock industries throughout tropical and other world regions. They affect animal productivity and wellbeing directly through their obligate blood feeding habit and indirectly by serving as vectors of the infectious agents causing bovine babesiosis and anaplasmosis. The monumental scientific discovery of certain arthropod species as vectors of infectious agents is associated with the history of research on bovine babesiosis and R. annulatus. Together, R. microplus and R. annulatus are referred to as cattle fever ticks (CFT). Bovine babesiosis became a regulated foreign animal disease in the United States of America (U.S.) through efforts of the Cattle Fever Tick Eradication Program (CFTEP) established in 1906. The U.S. was declared free of CFT in 1943, with the exception of a permanent quarantine zone in south Texas along the border with Mexico. This achievement contributed greatly to the development and productivity of animal agriculture in the U.S. The permanent quarantine zone buffers CFT incursions from Mexico where both ticks and babesiosis are endemic. Until recently, the elimination of CFT outbreaks relied solely on the use of coumaphos, an organophosphate acaricide, in dipping vats or as a spray to treat livestock, or the vacation of pastures. However, ecological, societal, and economical changes are shifting the paradigm of systematically treating livestock to eradicate CFT. Keeping the U.S. CFT-free is a critical animal health issue affecting the economic stability of livestock and wildlife enterprises. Here, we describe vulnerabilities associated with global change forces challenging the CFTEP. The concept of integrated CFT eradication is discussed in reference to global change.

Ambient NH3 concentrations were measured at a beef cattle CAFO during the spring and summer months of 2007. Concentrations were measured every five minutes, 24-hours per day at a sample intake height of 3.3 m using a chemiluminescence analyzer. On site weather data was collected concurrently. Emission rates were estimated using a backward Lagrangian Stochastic model (WindTrax 2.0.7.8). Mean 24-hr concentrations for spring were 0.498, 0.597 and 0.568 ppm for March, April and May, respectively. Corresponding fluxes for March, April and May were 57.76, 123.10 and 86.34 µg m-2 sec-1, respectively. Summer mean ambient concentrations were 0.684, 0.702 and 0.568 ppm for June, July and August, respectively. Summer fluxes were 85.27, 75.06 and 71.56 µg m-2 sec-1 for June, July and August, respectively.

More than 7 million beef cattle are fed in open-lot feedlots in the Texas High Plains. As urban populations encroach upon rural agricultural communities, concerns about nuisance issues escalate. One of the nuisance concerns for feedlots and nearby neighbors is flying insects. House flies and stable flies are the primary problem insects at feedlots. Not only are flies a nuisance, but certain types of flies can negatively affect animal performance, resulting in lost revenues. During a seven month period in 2000 and 2001, fly populations were monitored at two research feedlots and six commercial feedlots. Insect populations were determined using insect traps (alsynite panels, sticky tape, bait traps). Traps were monitored twice a weak and house flies and stable flies were counted and identified. The predominant fly species were the house fly (Musca domestica) and the stable fly (Stomoxys calcitrans). All sites had fly population peak activity during mid-June through September. The house fly population decreased significantly from 2000 to 2001 due to environmental conditions. Stable fly populations were more prevalent at feedlots with higher head capacities. Data indicate that the house fly population was affected more by an integrated pest management program than the stable fly population.

Rhizoctonia solani infection of potato causes seed piece decay and stem and tuber lesions, resulting in delayed emergence and uneven stands, low-vigor plants and unmarketable tubers. Rhizoctonia prevention effectiveness of three fungicide/fir bark dusts and nontreated tubers were compared on three varieties. Seedpieces of Viking, Atlantic and Norkotah 278 were treated and planted in separate commercial fields. A randomized complete-block design with four replications with four 26-foot rows per treatment plot included four treatments: 0.5 lb Maxim, 1.0 lb Tops MZ, and 1.5 lb Nubark Captan dust/100 lb seed. Plant stems, stolons and tubers were examined for Rhizoctonia infection at the tuber initiation stage and tubers were examined again at mature stage. Maxim and Tops MZ reduced stolon infection in Atlantic and Norkotah 278 and reduced stem infection in Norkotah 278. Plants from Maxim treated tubers produced more stems/plant in Norkotah 278 and produced more weight of tubers weighing less than four oz in all three varieties. Differences in seed tuber conditioning and mechanical damage in seed handling increase variability of treatment effects. Repeated testing of potato seed piece treatments in Texas High Plains conditions is the best way to confirm potential of beneficial effects of seed treatment.