Research on identification of Ceutorhynchus spp. on winter oilseed rape in Latvia was done during the vegetation season of 2009 and 2010. Field trials were located in the Research and Study Farm ''Peterlauki'', Jelgava municipality, Latvia (56 deg 32 min 17.38N, 23 deg 43 min 17.65E). Four species of brassica stem weevils were identified: cabbage stem weevil Ceutorhynchuspallidactylus Marsh., syn. C. quadridens Pan., rape winter stem weevil C. picitarsis Gyll., blue stem weevil C. sulcicollis Pay., and C. typhae Herb. One of the most common species in winter oilseed rape was cabbage stem weevil C. pallidactylus. Use of a sweep net for identification of particular species cannot be applied, as in practice no specimens have been collected by this method. One of the most appropriate methods for identification of Ceutorhynchus spp. on winter oilseed rape has been yellow sticky traps and water traps that have been used to collect the greatest number of specimens (24) during the vegetation season. First pests appear during the 2nd decade of April, when the plant reaches 33 BBCH. Pest control using systemic insecticide Proteus 110 OD (tiakloprid 100 g LE-1, deltametrin 10 g LE-1) with a dose of 0.75 L haE-1 was applied when the plant reached 39-44 BBHC. Despite the high population density (2 to 10 insects on 40 plants), significant (p is less than 0.05) decrease in pest damage by 43-51%, when compared to untreated area, was recorded during vegetation seasons of 2009 and 2010. Pest control with a systemic insecticide when the plant is in the stem elongation phase provided a significant (p is less than 0.05) yield increase of 0.5 to 0.7 thaE-1.

Chemical composition of crops before winter is important for successful overwintering of plants. The aim of the research, carried out from 2007/2008 till 2009/2010 at the Research and Study farm ‘Vecauce’, was to investigate the influence of agricultural practices (sowing date, sowing rate, and fungicide application) and meteorological conditions during winter on the content of sugar in apical bud and root of two types of winter oilseed rape (Brassica napus L.) cultivars. The content of sugars (monosaccharides) in apical bud and root in autumn and following spring was analysed using the Luff–Schoorl method. Sugar content in apical bud and root of winter oilseed rape in autumn and spring differed depending on the trial year, because of different, even contrary (in season 2009/2010), meteorological conditions. Sugar content was higher in plant parts developed when rape was sowed on earlier sowing dates, but it was substantially influenced by the sowing date only on some occasions. Sowing rate had no impact on sugar content in apical bud and root. Application of a fungicide as a growth regulator had no significant impact on the result, but sugar content decrease during winter 2009/2010 in the root of winter oilseed rape was smaller when fungicide as growth regulator was applied.

The spread of thrips was observed in winter rye, wheat and triticale crops during the growing season of 2001 at the Lithuanian Institute of Agriculture in Dotnuva. Thrips started to spread in winter cereals of the end of tilling - beginning of stem elongation stage (DC 29-30). In winter rye and triticale the spread of thrips was similar. There were two well-defined peaks of thrips occurrence. The highest incidence of thrips was on winter rye. There were 100% infested stems and 15.4 thrips per infested stem in rye, 90% infested stems and 6.9 thrips per infested stem in triticale and 84% infested stems and 2.9 thrips per infested stem in wheat.