Scientific Commission, I.H.G.C., Hop Research Center Hüll, D-Wolnzach
Abstract
In the first three decades of the 20th century, quassia extract was widely used in hop growing as a chemical agent to control Phorodon humuli and other insect pests. In the first years of the 21st century this compound was rediscovered by German organic hop growers. In nine efficacy trials conducted in five field seasons, quassia products proved to be effective control agents for P. humuli in organically grown aroma cultivars. As the best method of application a systemic variant was developed by painting a suspension of quassia extract to the bines. This method proved not only to be very effective but was also best from an environmental point of view as sprayed quassia extracts had side effects on non-target organisms. As an optimal systemic application rate 24 g/ha of the active ingredient quassine was determined
