Current problems in the protection of winter rapeseed (Brassica napus var. napus L.) | Aktuelni problemi u zaštiti ozime uljane repice (Brassica napus var. napus L.)

The rapeseed (Brassica napus var. napus L.) is grown for seeds that contain 40-48% oil and 18-25% protein. The oil is high quality and it can be used for food. In our country, rapeseed oil is produced primarily for biodiesel. As with other crops, yield reduction may be caused by climatic factors and agricultural practices including a belated control of weeds, insects and phytopathogenic fungi. The wild mustard (Sinapis arvensis) is the major weed in the rapeseed, mostly because it comes from the same family and has similar genetic background as the rapeseed. The wild mustard causes multiple negative effects in rapeseed crop. The high content of erucic acid in mustard seed impairs oil quality, and the cake cannot be used as animal feed because of the presence of glucosinolates. Such oil renders low-quality biodiesel. Most herbicides are ineffective in the control of wild mustard in rapeseed crop. The rapeseed is also attacked by a large number of insect pests. Major pests in the fall are the cabbage stem flea beetle (Psylliodes chrysocephala) and the turnip sawfly (Athalia rosae). Both species may cause total damage. Major pests in the spring are the common pollen beetle (Meligethes aeneus) and weevils (Ceutorhynchus spp.). It has been reported that the activity of pollen beetle imagoes and larvae may reduce rapeseed yield up to 50%. One or more chemical treatments are needed to effectively control this pest. Second and third treatments may cause problems because they coincide with high activity of sensitive pollinating insects. Currently, the major phytopathogenic fungi are Sclerotinia sclerotiorum, Phoma lingam and Peronospora parasitica. The above pests are present in all rapeseed-growing regions. Although the damages caused so far have been negligible, the increasing frequency of pest occurrence seems to indicate that these pests may pose serious problems in rapeseed production in coming years.