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  • Friday, May 8, 2015
  • 1:30 PM–2:20 PM
  • Science Building 010

Jenna Van Bruggen & Jenai Quan

Jenna Van Bruggen

Variation of phenotypic characteristics in populations of Sclerotinia sclerotiorum causing white mold of snap bean in New York

White mold, caused by Sclerotinia sclerotiorum, is one of the most economically damaging diseases of snap bean (Phaseolus vulgaris) and other vegetables. The goals of this project were to compare aggressiveness on snap beans among different isolates of S. sclerotiorum, and test for resistance to a commonly-used fungicide. Sclerotia were also conditioned to carpogenically germinate for the production of ascospores for use in field trials quantifying fungicide efficacy. Seventeen isolates were used in detached pod and leaf assays which quantified aggressiveness by measuring lesion size. The reproducibility of results between replicates from the pod assay was higher than using leaves. Moreover, in the leaf and pod assays, results were similar for some of the isolates. Significant variation in aggressiveness between isolates was also found. Of the isolates (n = 8), all were sensitive to the fungicide thiophanate-methyl at 10 mg/L based on a mycelial growth assay.

Jenai Quan

Small-Scale Variability of Metals in an Urban Garden in Detroit, Michigan

This project evaluated the distribution of seven metals (As, Cr, Cu, Mn, Ni, Pb, and Zn) in an urban garden in northeast Detroit.  It was postulated that small-scale soil metal variability would be present and that higher metal concentrations would be found in areas of the garden plots where anthropogenic sources of metal pollutants were suspected. If these metals had shared sources, then covariance between their concentrations was also hypothesized to be present. Composite samples were collected following EPA protocol and nested grid sampling methods were used to investigate meter-scale variability. Soils were analyzed using x-ray fluorescence (XRF). Variability on the order of 3-10m was evident in variograms and in ordinary kriged concentration maps for each metal. The unique concentration patterns observed indicated that metals are not consistently present in greater concentrations in particular regions of the plots. Linear regression of collocated metal concentrations yielded statistically significant correlations (p≤0.05) among 14/21 metal pairs. The strongest correlation was between Pb and Zn (R2 = 0.63, p < 0.001). With the exception of As, concentrations of the metals investigated met MDEQ criteria for direct soil contact. These results are promising for urban gardening in Detroit. The protocols developed can be used for future soil studies in other small urban gardens. Further inquiry on XRF accuracy and the risk assessment levels guiding As criteria is recommended.


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