@article{neufeld_isard_ojiambo_2013, title={Relationship between disease severity and escape of Pseudoperonospora cubensis sporangia from a cucumber canopy during downy mildew epidemics}, volume={62}, ISSN={["1365-3059"]}, DOI={10.1111/ppa.12040}, abstractNote={Fundamental to the development of models to predict the spread of cucurbit downy mildew is the ability to determine the escape of Pseudoperonospora cubensis sporangia from infected fields. Aerial concentrations of sporangia, C (sporangia m−3), were monitored using Rotorod samplers deployed at 0·5 to 3·0 m above a naturally infected cucumber canopy in two sites in central and eastern North Carolina in 2011, where disease severity ranged from 1 to 40%. Standing crop of sporangia was assessed each morning at 07·00 h EDT and ranged from 320 to 16 170 sporangia m−2. Disease severity and height above the canopy significantly (P < 0·0001) affected C with mean concentration (Cm) being high at moderate disease. Values of Cm decreased rapidly with canopy height and at a height of 2·0 m, Cm was only 7% of values measured at 0·5 m when disease was moderate. Daily total flux (FD) was dependent on disease severity and ranged from 5·9 to 2242·3 sporangia m−2. The fraction of available sporangia that escaped the canopy increased from 0·028 to 0·171 as average wind speed above the canopy for periods of high C increased from 1·7 to 3·6 m s−1. Variations of Cm and FD with increasing disease were well described (P < 0·0001) by a log‐normal model with 15% as the threshold above which Cm and FD decreased as disease severity increased. These results indicate that disease severity should be used to adjust sporangia escape in spore transport simulation models that are used to predict the risk of spread of cucurbit downy mildew.}, number={6}, journal={PLANT PATHOLOGY}, author={Neufeld, K. N. and Isard, S. A. and Ojiambo, P. S.}, year={2013}, month={Dec}, pages={1366–1377} }
 @article{arauz_neufeld_lloyd_ojiambo_2010, title={Quantitative Models for Germination and Infection of Pseudoperonospora cubensis in Response to Temperature and Duration of Leaf Wetness}, volume={100}, ISSN={["1943-7684"]}, url={http://europepmc.org/abstract/AGR/IND44416978}, DOI={10.1094/phyto-100-9-0959}, abstractNote={ The influence of temperature and leaf wetness duration on germination of sporangia and infection of cantaloupe leaves by Pseudoperonospora cubensis was examined in three independent controlled-environment experiments by inoculating plants with a spore suspension and exposing them to a range of leaf wetness durations (2 to 24 h) at six fixed temperatures (5 to 30°C). Germination of sporangia was assessed at the end of each wetness period and infection was evaluated from assessments of disease severity 5 days after inoculation. Three response surface models based on modified forms of the Weibull function were evaluated for their ability to describe germination of sporangia and infection in response to temperature and leaf wetness duration. The models estimated 15.7 to 17.3 and 19.5 to 21.7°C as the optimum temperature (t) range for germination and infection, respectively, with little germination or infection at 5 or 30°C. For wetness periods of 4 to 8 h, a distinct optimum for infection was observed at t = 20°C but broader optimum curves resulted from wetness periods >8 h. Model 1 of the form f(w,t) = f(t) × (1 – exp{–[B × w]D}) resulted in smaller asymptotic standard errors and yielded higher correlations between observed and predicted germination and infection data than either model 2 of the form f(w,t) = A(1 – exp{– [f(t) × (w – C)]D}) or model 3 of the form f(w,t) = [1 – exp{–(B × w)2}]/cosh[(t – F)G/2]. Models 1 and 2 had nonsignificant lack-of-fit test statistics for both germination and infection data, whereas a lack-of-fit test was significant for model 3. The models accounted for ≈87% (model 3) to 98% (model 1) of the total variation in the germination and infection data. In the validation of the models using data generated with a different isolate of P. cubensis, slopes of the regression line between observed and predicted germination and infection data were not significantly different (P > 0.2487) and correlation coefficients between observed and predicted values were high (r2 > 0.81). Models 1 and 2 were used to construct risk threshold charts that can be used to estimate the potential risk for infection based on observed or forecasted temperature and leaf wetness duration. }, number={9}, journal={PHYTOPATHOLOGY}, author={Arauz, L. F. and Neufeld, K. N. and Lloyd, A. L. and Ojiambo, P. S.}, year={2010}, month={Sep}, pages={959–967} }
 @article{almany_de arruda_arthofer_atallah_beissinger_berumen_bogdanowicz_brown_bruford_burdine_et al._2009, title={Permanent Genetic Resources added to Molecular Ecology Resources Database 1 May 2009-31 July 2009}, volume={9}, ISSN={["1755-098X"]}, url={http://europepmc.org/abstract/med/21564933}, DOI={10.1111/j.1755-0998.2009.02759.x}, abstractNote={Abstract}, number={6}, journal={MOLECULAR ECOLOGY RESOURCES}, author={Almany, Glenn R. and De Arruda, Mauricio P. and Arthofer, Wolfgang and Atallah, Z. K. and Beissinger, Steven R. and Berumen, Michael L. and Bogdanowicz, S. M. and Brown, S. D. and Bruford, Michael W. and Burdine, C. and et al.}, year={2009}, month={Nov}, pages={1460–1466} }