Relatively little is known about the population biology of the legume pathogen Aphanomyces euteiches. A. euteiches is a soilborne pathogen causing Aphanomyces root rot of several legumes, including alfalfa, bean, lentil, and pea. Our objectives were to assess the degree of diversity, selfing, and population differentiation in A. euteiches. We contrasted populations within and among two geographically separated fields with a history of pea production. Molecular genotyping relied on amplified fragment length polymorphism analysis. Samples of A. euteiches recovered from two fields in northeast Oregon and western Washington confirmed previous reports of moderately high genetic diversity in populations of A. euteiches at the regional scale, but revealed higher-than-expected genotypic diversity within individual soil samples. Populations of A. euteiches were significantly differentiated at the soil sample, field, and regional level. The population structure appears to be patterned by regular selfing via oospores, a mixed reproductive system including both asexual and sexual reproduction, with occasional migration of novel genotypes or outcrossing.

In this study, 497 pea accessions from the Pisum core collection located at the USDA‐ARS, Western Regional Plant Introduction Station (WRPIS), Pullman, WA and seven woody‐stem pea lines from a private collection in the UK, were screened for resistance to Sclerotinia sclerotiorum, the cause of white mould. All of the Pisum genotypes screened were susceptible to infection, and 237 of the 504 genotypes were highly susceptible since these did not survive 2 weeks post‐inoculation. However, 22 pea accessions and one woody‐stem line were identified with quantitative partial resistance to white mould. Pea accessions 103709, 166084, 169603, 240515 and 270536 from the core collection demonstrated the greatest quantitative partial resistance to S. sclerotiorum based on nodal resistance and plant survival in replicated greenhouse and laboratory tests. Only five of the 504 genotypes screened had a mean lesion length of between 0 and 1 cm when assessed 3 days post‐inoculation. Pea stem diameter was significantly (P ≤ 0·03) negatively correlated with stem lesion length in replicated greenhouse and laboratory experiments, and was determined to be the best predictor of quantitative partial resistance to S. sclerotiorum based on lesion length.

The importance of shielding temperature sensors from solar radiation is understood, but there is a lack of prescriptive advice for plant scientists to build inexpensive and effective shields for replicated field experiments. Using the general physical principles that govern radiation shielding, a number of low-cost, passively ventilated radiation shields built in-house was assessed for the measurement of air temperature against the same type of sensor in a meteorological “standard” Gill radiation shield. The base shield material had high albedo (≈0.9) and low emissivity (0.03). Aspirated shields were included for simultaneous measurements of temperature and relative humidity. Differences in air temperature (ΔT) between low-cost shields and the standard Gill were greatest for shields with open bottoms (up to +7.4 °C) and for those with poorly perforated sidewalls. Open-bottomed shields were prone to heating from reflected radiation. Tube-shaped shields appeared to require more than 30% sidewall perforation for convection by ambient wind (up to 4 m·s−1) to offset the midday radiation load of the shield. The smallest daytime ΔT were between aspirated shields and the standard Gill, averaging less than ±0.5 °C. Among passively ventilated shields, the smallest daytime ΔT consistently were produced by a shield that emulated the stacked plate design of the standard Gill for a total of U.S. $4.00 in materials and 45 min construction time. Eighty-nine percent of all daytime ΔT for the “homemade Gill” shield was 1.5 °C or less. The combination of low ambient wind speed (less than 1 m·s−1) and high global irradiance (greater than 600 W·m−2) produced the largest ΔT for all passively ventilated shields, the magnitude of which varied with shield design; stacked plate configurations were more effective shields than were tube-based configurations. Nighttime ΔT were inconsequential for all shields. Cost-effective radiation shielding can be achieved by selecting shield materials and a configuration that minimize daytime radiation loading on the shield while maximizing the potential for convective transfer of that radiation load away from the shield and the sensor it houses.

Many ecological studies have focused on the effects of transgenes in Þeld crops, but few have considered multiple transgenes in diversiÞed vegetable systems. We compared the epigeal, or soil surface-dwelling, communities of Coleoptera and Formicidae between transgenic and isoline vegetable systems consisting of sweet corn, potato, and acorn squash, with transgenic cultivars expressing Cry1(A)b, Cry3, or viral coat proteins. Vegetables were grown in replicated split plots over 2 yr with integrated pest management (IPM) standards deÞning insecticide use patterns. More than 77.6% of 11,925 insects from 1,512 pitfall traps were identiÞed to species, and activity density was used to compare dominance distribution, species richness, and community composition. Measures of epigeal biodiversity were always equal in transgenic vegetables, which required fewer insecticide applications than their near isolines. There were no differences in species richness between transgenic and isoline treatments at the farm system and individual crop level. Dominance distributions were also similar between transgenic and isoline farming systems. Crop type, and not genotype, had a signiÞcant inßuence on Carabidae and Staphylinidae community composition in the Þrst year, but there were no treatment effects in the second year, possibly because of homogenizing effects of crop rotations. Communities were more inßuenced by crop type, and possibly crop rotation, than by genotype. The heterogeneity of crops and rotations in diversiÞed vegetable farms seems to aid in preserving epigeal biodiversity, which may be supplemented by reductions in insecticide use associated with transgenic cultivars.

Increasing labor costs and changes in labor forces have prompted an increased demand for automation in specialty crop production. Implementation of technological innovations in the agricultural sector tends to be slow, thus this study investigated motivations and perceptions of technology. Using qualitative interviewing and analysis, this study used a diffusion of innovations framework to gain insight into what channels of communications impacted planned adoption rates and what aspects of technology influence the decision-making process. Interview participants emphasized the inevitability of implementing new technologies while considering the capital investment of more complex technology, changes in labor management to integrate technology, applicability of technology to current practices, and trust in technology designers.

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Pesticide spray drift represents an important cause of crop damage and farmworker illness, especially among orchard workers. We drew upon exposure characteristics from known human illness cases to design a series of six spray trials that measured drift from a conventional axial fan airblast sprayer operating in a modern orchard work environment. Polyester line drift samples (n = 270; 45 per trial) were suspended on 15 vertical masts downwind of foliar applications of zinc, molybdenum, and copper micronutrient tracers. Samples were analyzed using inductively coupled plasma mass spectrometry and resulting masses were normalized by sprayer tank mix concentration to create tracer-based drift volume levels. Mixed-effects modeling described these levels in the context of spatial variability and buffers designed to protect workers from drift exposure. Field-based measurements showed evidence of drift up to 52 m downwind, which is approximately 1.7 times greater than the 30 m (100 ft) ‘Application Exclusion Zone’ defined for airblast sprayers by the United States Environmental Protection Agency Worker Protection Standard. When stratified by near (5 m), mid (26 m), and far (52 m) distances, geometric means and standard deviations for drift levels were 257 (1.8), 52 (2.0), and 20 (2.3) µl, respectively. Fixed effect model coefficients showed that higher wind speed [0.53; 95% confidence interval (CI): 0.35, 0.70] and sampling height (0.16; 95% CI: 0.11, 0.20) were positively associated with drift; increasing downwind distance (−0.05; 95% CI: −0.06, −0.04) was negatively associated with drift. Random effects showed large within-location variability, but relatively few systematic changes for individual locations across spray trials after accounting for wind speed, height, and distance. Our study findings demonstrate that buffers may offer drift exposure protection to orchard workers from airblast spraying. Variables such as orchard architecture, sampling height, and wind speed should be included in the evaluation and mitigation of risks from drift exposure. Data from our study may prove useful for estimating potential exposure and validating orchard-based bystander exposure models.