Effect of Quassan, a Quassia product, against Sawflies (Hoplocampa testudinea)

Summary in the original language of the document

Since reduction in effectivity 01 the bitter wood preparation Quassan in the years 1999 and 2000, the quality 01 the product had to be criticised. Quality control has since been improved, in so lar as each batch is now tested in a biotest on aphids belore dispatch. Parallel to its normal use in the lield, the effect 01 Quassan was also lield tested in 2001 against apple sawflies. Quassan was tested in dillerent concentrations per hectare and the effect compared with an untreated control as well as with plots treated with a sell-cooked Quassiawood extract. Ali the methods showed an efficacy 01 80% or more as compared with the control. Differences due to concentration per hectare used were only minimal.