An exotic plant cultural landscape inventory, area wide survey, and natural resource area invasiveness assessment was conducted in 2002 at the Roosevelt-Vanderbilt (ROVA) National Historic Sites (NHS) in Hyde Park, NY. At the species level, 40% of 90 assessed landscape species had not escaped cultivation, 44% had escaped and invaded natural resource areas, and 16% were categorized as migratory invaders. The most prolific introduced woody trees and vines at ROVA are members of the trumpetvine, bittersweet, pea, buckthorn, quassia, and grape families (Bignoniaceae, Celastraceae, Fabaceae, Rhamnaceae, Simaroubaceae, and Vitaceae, respectively). Shrub species occurring with more frequency in the natural areas than other escapes are the introduced native atlantic nine bark (Physocarpus opulifolius), burning bush (Euonymus alatus), forsythia (Forsythia sp.), japanese barberry (Berberis thunbergii), morrow’s honeysuckle (Lonicera morrowii), tatarian honeysuckle (Lonicera tatarica), and mock orange (Philadelphus sp.). For the subset of assessed woody vines, shrubs, and tree species found in cultivation for at least 50 to 67 years (the “50 plus club species”), slightly more had escaped from cultivation for the Vanderbilt Mansion (VAMA) and Eleanor Roosevelt (ELRO) estates but for the Franklin Delano Roosevelt (FDR) collection the numbers were equivalent. The approach used in this study illustrates with data the “movement” of exotics over a significant period of time and underscores the importance of site-specific and species-specific assessments. This assessment also emphasizes the value of understanding the history (e.g., cultivated, cultivated escaped, or migratory invaders), purpose (e.g., aquatic, crop garden forb, groundcover, ornamental, or weed), and management over time (e.g., long since abandoned, recently abandoned, or still maintained, etc.) of the geographic area under consideration and the use of available exotic invasive plant lists to conduct such assessments.
A series of field studies were conducted from 1999 to 2005 in Ithaca, NY, at the Cornell Turfgrass Research Center as part of the National Turfgrass Evaluation Program (NTEP) to evaluate a collection of 78 fine-leaf fescue cultivars (Festuca spp.) for turfgrass quality, seedling vigor, and ability to inhibit the establishment of common annual and perennial weeds. Using these criteria, we evaluated the overall suitability of the cultivars for use in turfgrass settings, as well as their potential weed suppressive or allelopathic ability. The ability of fine-leaf fescue to displace weeds was visually evaluated by density-wise comparison, and several cultivars of the 78 studied consistently established well and provided good to very good suppression (greater than 70%) of common turf weeds when established at the same planting density. Other cultivars provided moderate (between 35% and 70%) to (< 30%) little weed suppression. Greater weed suppressivity is likely associated with the differential ability of fescue cultivars to establish rapidly and to form a dense canopy, as well as potential allelopathic interference. This study was conducted in conjunction with laboratory experiments that revealed that certain fine-leaf fescue cultivars produced phytotoxic root exudates that were released into the rhizosphere over time. Additional field studies conducted in Ithaca showed that cultivars Intrigue, Columbra, and Sandpiper were consistently more weed suppressive than the other fine-leaf fescues evaluated. Although our understanding of the dynamics of production and degradation of fine-leaf fescue root exudates in the rhizosphere is limited, recent field studies also suggest that allelopathic interference as well as the ability to rapidly establish influence subsequent weed infestation in fine-leaf fescue stands. From a more practical standpoint, certain fine-leaf fescue cultivars, including Intrigue, Columbra, Sandpiper, and Reliant II, could be recommended for use in low-maintenance turf settings in the northeastern United States due to their aesthetic appeal and their limited weed infestation in circumstances where herbicides are not applied.