Susceptibility ranking of more than 50 clones of hybrid Populus whips showed a wide range of attack ranging from none to very heavy. Clones with P. x jackii parentage were the most susceptible, whereas Carolina poplar was unscathed. Growth loss differed little between very heavily aphid-attacked whips and unattacked whips. Two insecticidal soaps adequately controlled the aphid but one caused some phytotoxicity to Populus.
Wilson, Louis F. and Moore, Lincoln M.
"Preference for Some Nursery-grown Hybrid Populus Trees by the Spotted Poplar Aphid and Its Suppression by Insecticidal Soaps (Homoptera: Aphididae),"
The Great Lakes Entomologist: Vol. 19
, Article 3.
Available at: http://scholar.valpo.edu/tgle/vol19/iss1/3