Failure of Foliar-Applied Biostimulants to Enhance Drought and Salt Tolerance in Urban Trees

Urban environments present an array of environmental conditions detrimental to the biology of trees. Two major problems include deicing salts, a common soil pollutant, and drought. One potential option for managing these enviro mental disorders may be through the application of commercially available biostimulants, as these products are reported to enhance a plant's resistance to environmental stresses. Trials used containerized stock of evergreen oak (Quercus ilex), holly (Ilex aquifolium), rowan (Sorbus aucuparia), and beech (Fagus sylvatica) to evaluate the effectiveness of seven commercially available biostimulants as drought and salt protectant compounds. Results conclude that none of the biostimulants evaluated in this study provided any significant degree of salt or drought damage protection compared to water-treated controls.