Onion storage in sterilized new plastic crates compared to storage in old wooden boxes.

The United States Food and Drug Administration?s (FDA) proposed water rules to implement the Food Safety Modernization Act (FSMA). The FDA has proposed that plastic totes be substituted for wooden bins for the storage on onion bulbs. A preliminary study was conducted to examine the role of wooden storage containers on onion bulb contamination with E. coli. Onions from a furrow-irrigated field using water up to 866 MPN E. coli /100 ml were harvested into 12 old wooden boxes and 12 sterilized new plastic crates. Onions from a drip-irrigated field using water with 0 MPN E. coli /100 ml were harvested into 12 old wooden boxes and 12 sterilized new plastic crates. Onions packed out tended to not have E. coli on the bulb exteriors. The small amount of contamination detected did not appear to be related to the storage containers or irrigation water source

Survival of Escherichia coli on onion during field curing and packout.

The Food and Drug administration has expressed concern that Onions (Allium cepa) irrigated with water contaminated with high rates of Escherichia coli could harbor E. coli on their surface or interior. On the other hand, since onions contain antimicrobial compounds and field conditions may not be conducive to E. coli survival, the E. coli population on the surface of onions might become negligible through the course of field curing. Further, the relationship between the E. coli in the irrigation water to the E. coli on onion bulbs after field curing, harvest, and packout has not been studied. To determine if E. coli should be of concern in onion production, we sought to measure the die-off of E. coli on onions between the last irrigation and harvest and the presence of E. coli on onions after packout. Well water was tested and had no E. coli; ditch water intentionally run across a pasture prior to use had 218 to > 2400 MPN of E. coli/100ml. Onions were sampled from those furrow irrigated (ditch water) and those drip irrigated (well water) starting at lifting 3 September 2013 for four consecutive weeks. At 0 and 28 days after lifting, both interior and exterior of the onions were tested for E. coli. At 7, 14, and 21 days after lifting, only the exterior of the onions was tested. None of the onions contained E. coli internally at 0 or 28 days after lifting. At lifting E. coli was present on the exterior of both the drip and furrow irrigated onions and seemed to be largely unrelated to the irrigation water. The exterior E. coli contamination decreased rapidly after lifting. After harvest and packout on 14 October 2013, no E. coli was detected on the onion bulb exteriors from either irrigation treatment. E. coli introduced into the onion field through furrow irrigation was not present on or in the packed out onion bulbs

Movement of Escherichia coli in soil as applied in irrigation water.

The US Food and Drug Administration (FDA) has proposed that If irrigation water exceeds 235 colony-forming units (CFU) of E. coli /100 ml in any one sample or 126 CFU/100 ml in the average of any five consecutive samples, growers would have to cease using that water in any way that directly contacts the surface of fresh produce (FDA 2013). The FDA has proposed that these E. coli levels are an indication of high risk of bacterial contamination of fresh onion (Allium cepa L.) bulbs regardless of the irrigation system. If onion irrigation exceeds 235 CFU, it is not known whether the contaminated water applied by furrow or drip irrigation actually reaches the onion bulb. Soil could filter E. coli and other bacteria before irrigation water reaches onion bulbs. ?Vaquero? onions were grown on Owyhee silt loam. In our preliminary studies reported here, well water free of E. coli was applied to onions through drip irrigation or through furrow irrigation. A second water source was intentionally enriched with E. coli by being run across a pasture and recaptured prior to use. Furrow and drip irrigation were used to apply this water containing 218 to >2400 MPN/100ml for 11+ hours per irrigation. E. coli was monitored in the soil water at the end of irrigation cycles through direct sampling of the soil. Soil water was also sampled using sterile soil solution capsules (SSSC) to sample E. coli in the soil water that moved into place, to differentiate the movement of soil water from the soil water already in place. Soil water measurements were made adjacent to the water source, half way to the bulbs, and immediately adjacent to the onion bulbs. For furrow irrigation with ditch water the E. coli counts in the soil next to the onion bulbs was only 0% and 21% of the counts in the irrigation water following the first and second irrigations, respectively. During subsequent furrow irrigations, the E. coli counts in the soil water next to the onion bulbs exceeded the counts in the irrigation water. For drip irrigation with ditch water, the E. coli counts in the soil solution next to the onion bulbs remained very low. The soil water sampled by the SSSC adjacent to the onion bulbs drip-irrigated with ditch water also had very low E. coli counts

Review of two decades of progress in the development of successful drip irrigation for onions.

The irrigation needs of long day onion (Allium cepa) have been extensively studied at Ontario, Oregon, over the past 22 years. Drip irrigation has compared favorably with furrow and sprinkler irrigation systems. Onions were found to have very narrow soil moisture requirements. Drier soil than optima led to yield loss and wetter soil promoted bulb decomposition. Short term water stress at the three- to six-leaf stages of plant growth promoted multiple centers in long day onion varieties. Irrigation was successfully scheduled using soil water tension or evapotranspiration. Nitrogen fertilization and plant populations have been optimized. Drip system design must carefully consider the hydraulic conductivity of the soil in the placement of tape and onion rows since the soil moisture must wick over from the drip tape to the onion plant. The drip irrigation system design uniformity, operation, and maintenance are essential given onion?s low tolerance to water stress

Urban and Rural-residential Land Uses: Their Role in Watershed Health and the Rehabilitation of Oregon’s Wild Salmonids

This technical report by the Independent Multidisciplinary Science Team (IMST) is a comprehensive review of how human activities in urban and rural-residential areas can alter aquatic ecosystems and resulting implications for salmonid recovery, with a geographic focus on the state of Oregon. The following topics are considered in the form of science questions, and comprise the major components of this report: The effects of urban and rural-residential development on Oregon’s watersheds and native wild salmonids. Actions that can be used to avoid or mitigate undesirable changes to aquatic ecosystems near developing urban and rural-residential areas. The benefits and pitfalls of salmonid habitat rehabilitation within established urban or rural-residential areas. Suggested research and monitoring focus areas that will facilitate the recovery of salmonid populations affected by development. The fundamental concepts presented in this report should be applicable to most native salmonid populations across the state. IMST encourages managers and policy-makers with interest in a specific species or geographic region to carefully research local ecological conditions, as well as specific life history characteristics of salmonids in the region. Conserving watershed condition and salmonids in the face of increasing development requires consideration of two distinct sets of processes. First are the human social and economic processes that drive patterns in land use change. Second are the ecological processes, altered by land use, that underlie salmonid habitat changes. This report focuses on the latter and summarizes the effects of rural-residential and urban development on native, wild salmonid populations and the watersheds upon which they depend

Drip vs. furrow irrigation in the delivery of Escherichia coli to onions

Surface irrigation systems that reuse water may deliver bacteria to produce destined for fresh consumption. Four irrigation systems delivered (1) well water free of Escherichia coli via subsurface drip irrigation, (2) canal water with moderate levels of E. coli via subsurface drip irrigation, (3) canal water with moderate levels of E. coli via furrow irrigation, and (4) canal water with enhanced levels of E. coli via furrow irrigation. The four irrigation systems (replicated five times) applied water to onion on silt loam. Water was sampled hourly for E. coli, and the lateral movement of E. coli in the soil solution was tracked by soil samples following irrigations. Onion bulbs were sampled for E. coli contamination. The most probable numbers of E. coli in water and soil water were determined using IDEXX Colilert® and Colisure®, respectively, and Quanti-Tray/2000®. Under both furrow and subsurface drip irrigation, a fraction of the E. coli was delivered to the soil immediately adjacent to the onion bulbs. The silt loam retained most of the E. coli content away from the onion bulbs and close to where the water entered the soil. No E. coli was detected inside of the onion bulbs from any irrigation treatment. Current subsurface drip or furrow (flood) irrigation practices do not appear to pose a significant risk for bacterial contamination of dry bulb onion grown on silt loam

Investigating Europa’s Habitability with the Europa Clipper

The habitability of Europa is a property within a system, which is driven by a multitude of physical and chemical processes and is defined by many interdependent parameters, so that its full characterization requires collaborative investigation. To explore Europa as an integrated system to yield a complete picture of its habitability, the Europa Clipper mission has three primary science objectives: (1) characterize the ice shell and ocean including their heterogeneity, properties, and the nature of surface–ice–ocean exchange; (2) characterize Europa’s composition including any non-ice materials on the surface and in the atmosphere, and any carbon-containing compounds; and (3) characterize Europa’s geology including surface features and localities of high science interest. The mission will also address several cross-cutting science topics including the search for any current or recent activity in the form of thermal anomalies and plumes, performing geodetic and radiation measurements, and assessing high-resolution, co-located observations at select sites to provide reconnaissance for a potential future landed mission. Synthesizing the mission’s science measurements, as well as incorporating remote observations by Earth-based observatories, the James Webb Space Telescope, and other space-based resources, to constrain Europa’s habitability, is a complex task and is guided by the mission’s Habitability Assessment Board (HAB)