The densities of goldenrod galls (Eurosta solidaginis) and their goldenrod host plants (Solidago canadensis) while directly related to each other, are not impacted by soil nitrogen or soil moisture.

Abstract

The purpose of this study was to determine the effects that soil moisture and soil nitrogen content had on the density and abundance of goldenrod galls (Eurosta solidaginis) on their host plant goldenrod (Solidaginis canadensis) near the shores of Lake Michigan. I tested the relationship between the number of goldenrod plants and number of galls, the soil moisture and gall density, the soil nitrogen content and gall density and the total number of galls and number of double galls. Plots were found in Cross Village Park, Cross Village, MI at varying of distances along transects. I counted the total number of goldenrod plants, how many galls were present and also recorded the occurrence of double galls in each plot. Soil samples were also taken to determine soil moisture and nitrogen content.There was a direct, significant relationship between the number of goldenrod plants and goldenrod galls and also with the total number of galls and number of double galls. There was no significant correlation between soil moisture and gall density or with soil nitrogen content and gall density. In conclusion, only the numbers of goldenrods significantly influenced the distribution of goldenrod galls, which then influenced abundance of double galls; however soil moisture and nitrogen content had no affect on gall density.