The resistance of winter wheat varieties to Puccinia recondite f. sp. tritici was investigated at the Lithuanian Institute of Agriculture during 2001–2003. Effectiveness of resistance genes was investigated at seedling, tillering and adult plant stages. Virulence tests done during the 2000–2003 period showed that the majority of Lr genes used in European wheat were not sufficiently efficient. However, testing of cultivars at the first leaf stage revealed that the Lr37 gene in combination with the other genes was very effective. The experimental cultivars were sown in 2 times: in autumn and spring, without vernalization. The main task of spring-sown nursery was to improve the effectiveness of the experiment and investigate the effect of different Lr genes of non-vernalized plants at tillering growth stage. The Lr37 gene was found to be the most effective at both adult plant stage and tillering growth stage. Disease severity and plant resistance type at tillering stage were stable in all experimental years, which is important for the breeding program. The investigations revealed that the correlations between resistance at seedling and the other two stages were up to r = 0.81 (significant at p = 0.01**). The correlations between leaf rust severity and varietal resistance type at tillering were very high (r = 0.86–0.91**) in the same year. The correlation of leaf rust severity at adult plant stage was strong (r = 0.78**) between 2001 and 2002, but too low for reliable selection of resistant cultivars in the other years. Spring-sown nursery was complementary to collect resistance data in the years unfavourable for leaf rust development.

The outdoor pot experiments on the influence of weeds' growth stage and climate conditions on herbicides' effect were carried out in the Danish Institute of Agriculture Science in 2000-2001. The experiment concerning growth stage took into consideration three phases of Galium aparine: l, 2 and 3 whorls. The influence of temperature was performed using climate simulator running at three temperatures: 8/2°C, l 6.5/8°C, 24/16°C. The rain was applied using rain simulator 1, 3 and 6 hours after herbicides' treatment. Herbicides: Grody! 75 WG (amidosulfuron 750 g*kg-1), Aurora Super 61,5 WG (mecoprop 600 g=kg' + carfentrazone-ethyl 15 g*kt1), Lintur 70 WG (dicamba 65.9 g=kg', triasulfuron 4.1 g=kg') and Chwastox Trio 540 SL (dicamba 40 g*r1, MCPA 200 g"l', mecoprop 300 g*r') were applied in four doses: full recommended, 1/2, 1/4 and 1/8 of full dose on G. aparine. Grody! 75 WG and Aurora Super 61,5 WG were the most efficient to the youngest plants of G. aparine. Differences in susceptibility among three growth stages (1, 2, 3 whorls) to Grody! 75 WG were higher than to Aurora Super 61,5 WG. Effectiveness of tested herbicides tended to increase as temperature rose. The addition of adjuvant improved activity of herbicide Lintur 70 WG that showed satisfactory weed control even at four time reduced dose independently from temperature. The rain treatment 1, 3 and 6 hours after spraying caused reduction of Aurora Super 61,5 WG activity at 1/4 and 1/8 doses. The half dose gave a good result only when rain was applied 6 hours after treatment. Herbicide Grody! 75 WG was efficient after rain application (1, 3, 6 HAT) only at full dose.