Facts:
Link to the final report (in Swedish)
Reference to the Norwegian study:
Trandem N, Vereide R, Böthun M 2010 Høstsprøyting med rapsolje har overraskende god effekt mot bladmidd i bringebær. Norsk frukt og bær 5, 20-22.
SLU news
Rapeseed oil against Raspberry Leaf Mite
Published: 12 December 2011
Treatment with a mixture of rapeseed oil and soap in the autumn may limit the occurrence of Raspberry Leaf and Bud Mite. This may imply good possibilities for a pest control strategy of the mite inorganic raspberry cultivation.
Damages from the Raspberry Leaf and Bud Mite (Phyllocoptes gracilis) is a problem in the cultivation of summer raspberries. The popular variety Glen Ample is easily attacked by the mite. The symptoms are yellow spots on the leaves and both yield and quality of the berries deteriorate.
During the fall, various control strategies against the Raspberry Leaf and Bud Mite were tested at Rånna experimental station in southwestern Sweden. Rapeseed oil with added soap and sulfur were tested in an organic summer raspberry cultivation. The treatments were four sprays of 2% oil + soap or two sprays of 4% oil + soap, or four sprays with 1.5% sulfur. Sprays were carried out during September-October. Sampling in late October showed that the presence of the Raspberry Leaf and Bud Mite in the buds of Glen Ample was significantly reduced by 4% oil + soap.
The experiment shows that it is possible to reduce the amount of Raspberry Leaf and Bud Mite during fall with a relatively high concentration of rapeseed oil with soap. Also Norwegian studies have shown good results from spraying with rapeseed oil against the Raspberry Leaf and Bud Mite. Further development of the methodology are however needed, but the trials completed so far indicate good possibilities to develop a pest control strategy against Raspberry Leaf and Bud Mite in organic raspberries.