MONOPOTASSIUM PHOSPHATE AS AN IN-SEASON FERTIGATION OPTION FOR POTATO

Monopotassium phosphate (MKP) is a potential option for fertigating phosphorus (P) in potato (Solanum tuberosum L.) when petioles are low in P and high in nitrogen (N); which is a situation where using ammonium polyphosphate (APP) could potentially result in excessive N application. Fertilizer trials were conducted in 2004–2006 with 0 or 56 kg P₂O₅ ha^?1 fertigated as either APP or MKP as a supplement to the pre-plant P (112 or 224 kg P₂O₅ ha^?1) broadcast applied to all plots. Supplemental P fertigation increased petiole P concentration, US No. 1 yield, and total yield over the control not receiving any in-season P fertilizer regardless of source. In addition, MKP increased tuber specific gravity. These results support previous studies showing that fertigated P can be used to increase potato yields when petiole P concentrations are low and that MKP is a viable substitute for APP fertilizer when fertigation is necessary.     

A size-based stock assessment model for invasive blue catfish in a Chesapeake Bay sub-estuary during 2001–2016

Stock assessment modeling provides a means to estimate the population dynamics of invasive fishes and may do so despite data limitations. Blue catfish (Ictalurus furcatus) were introduced to the Chesapeake Bay watershed to support recreational fisheries but also consume species of conservation need and economic importance. To assess management tradeoffs, managers need to understand the current status of the population and anticipate future population abundance and trends. A Bayesian size-based stock assessment model was used to estimate blue catfish abundance, fishing mortality, and size structure over time (2001–2016) in the tidal James River. The model estimated population size increases until around 2006, with declines in total abundance after 2011 and large blue catfish (≥80 cm total length) after 2001. These first estimates of blue catfish population dynamics in the Chesapeake Bay region provide inputs for projection models to evaluate prospective management actions and identify monitoring needs.     

Veterinary ocular microbiome: Lessons learned beyond the culture

Ocular pathogens cause many painful and vision‐threatening diseases such as infectious keratitis, uveitis, and endophthalmitis. While virulent pathogens and pathobionts play important roles in disease pathogenesis, the scientific community has long assumed disruption of the ocular surface occurs prior to microbial colonization and subsequent infection. While nonpathogenic bacteria are often detected in corneal and conjunctival cultures from healthy eyes, cultures also frequently fail to yield growth of common ocular pathogens or nonpathogenic bacteria. This prompts the following question: Is the ocular surface populated by a stable microbial population that cannot be detected using standard culture techniques? The study of the microbiome has recently become a widespread focus in physician and veterinary medicine. Research suggests a pivotal symbiotic relationship with these microbes to maintain healthy host tissues, and when altered is associated with various disease states (“dysbiosis”). The microbiota that lives within and on mammalian bodies have long been known to influence health and susceptibility to infection. However, limitations of traditional culture methods have resulted in an incomplete understanding of what many now call the “forgotten organ,” that is, the microbiome. With the introduction of high‐throughput sequencing, physician ophthalmology has recognized an ocular surface with much more diverse microbial communities than suspected based on traditional culture. This article reviews the salient features of the ocular surface microbiome and highlights important future applications following the advent of molecular techniques for microbial identification, including characterizing ocular surface microbiomes in our veterinary species and their potential role in management of infectious and inflammatory ocular diseases.     

Production Response of Freshwater Prawns Macrobrachium rosenbergii to Increasing Amounts of Artificial Substrate in Ponds

Abstract.— The response of freshwater prawns Macrobrachium rosenbergii to increasing amounts of artificial substrate was evaluated in ponds. Juvenile prawns (0.24 ± 0.13 g) were stocked into nine 0.04-ha ponds at 74,000/ha. Three control ponds received no artificial substrate while artificial substrate in the form of horizontal strips of polyethylene "construction fence" was added to the six treatment ponds to produce 40% or 80% increases in available surface area. Increasing availability of surface area produced a direct linear increase ( P < 0.05, r ²= 0.89) in total production with no significant change in average weight ( P > 0.05). There was an inverse linear relationship between available surface area and feed conversion ratios ( P < 0.01, r ² = 0.66) likely indicating increased availability of natural foods or reduced stress among animals. There was a direct linear increase in the percentage of females which achieved sexual maturity ( P < 0.01, r ²= 0.71) as the amount of added substrate was increased. Size and number of other sexual morphotypes were not significantly affected. These responses are consistent with those that would be expected if stocking densities were decreased. These data indicate that prawn production increases in direct relation to the amount of added substrate while utilizing feed more efficiently. The effect of substrate orientation on its functionality should be evaluated to allow further increases in substrate inclusion amounts for additional production intensification.