Table 1.
Location, size, climate, and crop characteristics of three areas in the western United States surveyed for feral alfalfa.
Table 2.
Variables used in generalized linear model explain the occurrence of feral populations and transgenic feral populations growing along rural road verges.
Fig 1.
Distribution of roadside feral alfalfa plants in Fresno County, California.
Hot spot analysis showed significant clustering of roadside feral populations (dark purple, dark orange) in alfalfa-seed (purple) and hay-production (orange) areas. Non-clustering populations are also evident (green). Transgenic feral populations (pink) occur in seed- and hay-production areas, as well as along major roads used to transport seed.
Fig 2.
Distribution of roadside feral alfalfa plants in Canyon County, Idaho.
Hot spot analysis showed significant clustering of roadside feral populations (dark purple, dark orange) in alfalfa-seed (purple) and hay-production (orange) areas. Non-clustering populations are also evident (green). Transgenic feral populations (pink) occur mainly in seed production areas.
Fig 3.
Distribution of roadside feral alfalfa plants in Walla Walla County, Washington.
Hot spot analysis showed significant clustering of roadside feral populations (dark purple, dark orange) in alfalfa-seed (purple) and hay-production (orange) areas. Non-clustering populations are also evident (green). Transgenic feral populations (pink) were clustered in seed and hay production areas.
Table 3.
Number of non-GE (-) and GE feral (+) populations observed at random and found sites in three study areas.
Table 4.
Stepwise logistic regression model for the influence of alfalfa production area, cropping pattern, roadside verge characteristics, transport spillage and climate on the occurrence of roadside alfalfa populations.
Fig 4.
Number of GE feral population occurrences relative to the distance from historic GE seed fields.
Relationship was significant but inconsistent across counties. In Fresno County, transgenic feral populations occurred more frequently at further distances from the single historic seed field, while in Canyon and Walla Walla counties, transgenic populations occurred closer to historic GE seed fields.
Table 5.
Logistic regression model for the influence of spillage during production and transport, population size, and proximity to historic GR hay and seed fields on the occurrence of transgenic roadside alfalfa plants.