Verticillium wilt of potato: a model of key factors related to disease severity and tuber yield in Southeastern Idaho

In three years (1994, 1995, and 1996), a total of 100 commercial potato fields in southeastern Idaho were surveyed for soil variables, severity of Verticillium wilt, soil inoculum density ofVerticillium dahliae andColletotrichum coccodes, colonization of stems, root, and tubers byV. dahliae andC. coccodes, and tuber yield, size, and quality. As a generalization, factors related to soil integrity (organic matter, organic nitrogen, and increased nutrient availability) were most closely related to wilt suppression and higher tuber yields, whereas factors related to loss of soil integrity (sodium and reduced nutrient availability) were related to increased wilt and lower tuber yields. In a multiple regression analysis, three independent variables, feeder-root infections byV. dahliae, sodium content in soil, and soil organic content, were significant predictors of tuber yield. With these three factors, this model accounted for 49%, 53%, and 62% of the field variability related to total yield in 1994, 1995, and 1996, respectively. Throughout this investigation,V. dahliae root infections had the most direct effect on tuber yield, which emphasizes the importance of quantifying root infections in epidemiological studies of Verticillium wilt. Based on these results, organic matter may be one factor that can be manipulated for suppression of Verticillium wilt without reducing soil populations of the pathogen.     

Some unique benefits with sudangrass for improved U.S. #1 yields and size of Russet Burbank potato

Three studies provided additional knowledge of beneficial effects of sudangrass for yield and quality increases of the Russet Burbank potato. Two of these studies showed significant increases of both U.S. #1 and smooth tubers > 280 g following green manures of sudangrass. These sudangrass (HS-33) effects did not differ from a sorghum-sudan hybrid (Trudan-8). When a sudangrass green manure was compared with a fallow treatment, results of the first study showed mean yield increases of 36% for U.S. #1 tubers > 280 g and yields of a second study by 34% for U.S. #1 tubers. This same sudangrass treatment outperformed green manures of either Austrian winter pea, barley, or sweet corn by increased U.S. #1 yields that ranged from 27% to 61%. By several lines of evidence, these benefits were found to extend beyond the effect of Verticillium suppression. Soil N was significantly increased following green manures of sudangrass, and these increases were in turn negatively correlated with wilt incidence and positively correlated with yields of both U.S. #1 tubers and tubers > 280 g. Additional benefits also included significant increases of tuber grade percentages for marketable tubers and of smooth tubers > 280 g. Benefits from sudangrass green manures beyond the effects of Verticillium suppression became further evident following a greenhouse study that involved field soil and sudangrass that had been grown in the same field. This study corroborated both field experiments by showing increased yields with green manures of sudangrass that approximated 5.5 t ha^-1 dry wt. As with the field studies, these yield benefits also extended beyond the effects of Verticillium suppression and were closely associated with significant increases ofFusarium equiseti, F. oxysporum, andF. solani. Throughout all studies, sudangrass green manures significantly increased microbial activities with increased populations ofFusarium spp. and increased concentrations in soil of mineralizable N, organic P, K, Mn, along with the percent soil organic matter -all factors that could have contributed to significant increases of yield and quality.     

Cosmetic powder suspensions in compliant, fingerprintlike contacts

Cosmetic powders are regularly employed in skin creams and cosmetic formulations to improve performance and enhance skin feel. A previous study investigated the effect of particle concentration and size on the lubricating properties of powder suspensions in smooth, compliant contacts [Timm et al., Tribol. Int. (2011)]. In this paper the tribological properties of cosmetic powder suspensions are investigated in compliant contacts having model fingerprintlike surface topography. Friction coefficients were measured for a series of powder suspensions with varying particle size and concentration in a polydimethylsiloxane (PDMS)/PDMS contact. A commercial tribometer (MTM, PCS Instruments) was employed to measure friction as a function of rubbing time (20 min), under pure sliding (50 mm/s) and low load (0.5 N) conditions. Compared to results using smooth surfaces, it was clear that surface topography has a pronounced affect on the time-dependent tribological behavior of the cosmetic powder suspensions studied. A two-stage friction coefficient versus time curve was observed. By varying the particle size and concentration it was shown that the duration and magnitude of each stage can be controlled.     

The effect of flow impedance on deposition of Cryptosporidium parvum oocysts with or without a vetiver buffer strip

Cryptosporidium parvum oocysts can be transported in overland flow from faecal deposits of grazing animals causing potential water contamination problems. Deposition of oocysts can occur when overland flow encounters vegetative buffers and its transport capacity is decreased in the upslope backwater region. Deposition of oocysts was investigated using a large rainfall simulator, with and without a vetiver buffer strip. Oocysts-spiked slurries were applied to two contrasting soils and the resultant oocyst/sediment depositions from the flow were compared. The buffers substantially reduced suspended sediment loads from the two soils and increased the oocyst concentration in the soil with >99% of the deposited oocysts measured upslope of the buffer.     

Effectiveness of using a mat filled with a peroxygen disinfectant to minimize shoe sole contamination in a veterinary hospital

OBJECTIVE: To determine the effectiveness of using a disinfectant mat filled with a peroxygen compound to prevent mechanical transmission of bacteria via contaminated footwear between the food animal ward and common breezeway of a veterinary teaching hospital. DESIGN: Observational study. SAMPLE POPULATION: Shoe soles of individuals entering and exiting from the ward. PROCEDURES: A mat filled with peroxygen disinfectant was placed at the entrance to the food animal ward, and participants wiped each shoe twice on the mat surface (n = 16) or walked on the mat surface but did not wipe their shoes (17) before entering and exiting from the ward. Swab specimens were collected from the shoe soles of participants before and after mat use and submitted for bacterial culture. RESULTS: For both study days, as participants entered the ward, median number of aerobic bacteria isolated from shoe swab specimens collected prior to use of the disinfectant mat was not significantly different from median number isolated after use of the disinfectant mat. However, as participants exited the ward, median number of aerobic bacteria isolated from shoe swab specimens collected prior to use of the disinfectant mat was significantly higher than median number isolated after use of the disinfectant mat. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that placing a mat filled with a peroxygen disinfectant at the exit from the food animal ward of a veterinary teaching hospital may help reduce mechanical transmission of bacteria on the footwear of individuals leaving the ward.     

Fixed‐time post‐cervical artificial insemination in weaned sows following buserelin use combined with/without eCG

Fixed‐time post‐cervical artificial insemination (FTAI) drastically reduces labour requirements and increases the use of boars with higher genetic merit. This study evaluated the efficiency of eCG administration combined with/without the GnRH agonist buserelin for the induction and synchronization of ovulation in weaned sows submitted to FTAI. The sows were allocated into three groups. In the control group, the first artificial insemination was performed at the onset of oestrus and repeated every 24 hr. In the eCG+GnRH group, sows received 600 IU eCG at weaning and buserelin (10 μg) after 86–89 hr of eCG, and in the GnRH group, sows received only buserelin after 86–89 hr of weaning. The hormone‐treated sows received a single FTAI after 30–33 hr of buserelin application. All the sows were inseminated with homospermic doses (1.5 × 10⁹ sperm cells/50 ml). The interval between weaning and ovulation was shorter (p < .05) in the eCG+GnRH (133.3 hr) and GnRH (135.9 hr) groups than the control (141.5 hr) group. In the eCG+GnRH group, the sows ovulated earlier (p < .05) than those in the GnRH group (44.5 vs. 48.2 hr after buserelin administration). The reproductive performance of GnRH sows was not compromised when only sows exhibiting oestrus at the time of insemination were considered, but lower farrowing rate and smaller litter size were observed in eCG+GnRH sows. The reproductive performance of eCG+GnRH sows was primarily compromised because the insemination was performed outside the optimal time relative to ovulation; therefore, it is advisable to inseminate them before 116–122 hr after weaning.