Glucosinolates with Brassica genus as secondary metabolites have a lot of functions and effects. Glucosinolates form less than 2% of the overall sulphur content at the beginning of vegetation in different parts of the plants and during growth their content is decreasing and forms less than 0.1%. This low representation doubts their storage function. With its chemical composition, they are ranked among natural pesticides with active and passive resistance against diseases and pests. They show repellent effects and properties of natural biofumigators in soil after ploughing in their biomass as green fertilizing, or after ploughing in after harvest the leftovers of rape. The principle of these effects is decomposition products of glucosinolates -bioactive isothiocyanates. Very important from this point of view are turnip rape Rex and Brassica juncea, whose content of these compounds is the highest one and they are resistant against the attack of Ceutorrhynchus pleurostigma. The same effect showed also when attacked by Phoma lingam. With other winter Brassicas either hybrid or linea and summer rape is this defensive system suppressed because of their lowered content due to breeding interferences, leading to limitation of their anti-nutritional negative effects. It is possible to state the final result after finding out the production of the above matter, roots, and after evaluation of the sorbal characteristics of the soil and evaluation of the state of health of the following crop or vegetable. After this overall analysis, it will be possible to evaluate the biofumigation properties of accessible varieties of the Brassica genus.

Small plot trials studying the impact of different seed treatments on the occurrence of pests and diseases in autumn were carried out during 2000-2003. The aim was to verify the efficiency of different fungicidal and insecticidal oilseed rape seed treatments and to determine the economical effectiveness of this method of protection. The following insecticidal seed treatments were used: Promet 400 CS (furathiocarb), Cosmos 500 FS (fipronil), Chinook 200 FS (imidacloprid & beta-cyfluthrin) and Marshal ST (carbosulfan). The seed treatment Chinook 200 FS in combination with newly developed fungicidal compound was also assessed. The most effective treatment was Chinook 200 FS (imidacloprid & beta-cyfluthrin), particularly against flea beetles (Phyllotreta spp.), and lower infestations by larvae of the turnip gall weevil (Ceutorhynchus pleurostigma Marsh.) were also found. However, the efficiency lasts no more than 4-5 weeks after sowing. The use of common insecticidal treatments in cases of necessity was found to be beneficial. Plant density in autumn and in spring was greatest in the Chinook 200 FS treatment and in some years a positive influence on yield was also observed with this treatment.