142Vol. 40, Plant Protect. Sci. & H��� 1983; P������ et al. 1984) in fecundity of the spider mite at higher temperatures. 1983) or decrease (B���� MATERIAL AND METHODSTetranychus urticae was reared on plants of green bean in laboratory conditions at a temperature of 23°C (± 2°C). Development and fecundity of the mite was determined in an air-conditioned box at diverse temperatures (15, 20, 25, 30 and 35°C) and on three host plants (Cucumis sativus L., Capsicum annuum L. and Phaseolus vulgaris L.). The leaf disk method was used; detached leaves were placed on water soaked cotton in a Petri dish (9 cm diameter). The Petri dish was placed onto a plastic cup (9 cm diameter and 5 cm depth) filled with water. Sufficient moisture for the filter paper was supplied by a strip of filter paper (1 cm wide) that was attached to the filter paper at one end while the other reached into the water in the cup via a small hole. For each variant (temperatures, host plants), five Petri dishes were used. To determine the development time of the spider mite, leaves of P. vulgaris with 10-15 freshly hatched eggs were used for each variant. We started with the series at 15°C and finished with the series at 35°C. To observe the fecundity of female mites, 10 young female mites were transferred with a soft brush to each combination following the abovementioned temperature sequence. The results were analysed statistically by the Tukey test. RESULTS AND DISCUSSIONFrom the results of our experiments it follows that temperature has a decisive impact on the time needed for development of T. urticae, whereas the differences between host plants were not significant (Table 1).Development was fastest at 35°C (6.50 d) and 30°C (6.93 d), averaged on the three hosts. P������ R�� et al. (1996) also found that the length of development of the spider mite at 30°C was 6.7-7.9 days. At other temperatures of our experiments, the development time was 9.27 d at 25°C, 12.06 d at 20°C and 16.23 d at 15°C. Thus, the higher the temperature, the faster the development of the spider mite. The differences in development time between temperatures was confirmed with high detectability in the statistical analyses, except for the differences between 30°C and 35°C. P������ et al. (1984) and D����� and M��������� (1986) state that a�er a certain increase in temperature and reaching a maximum of developments. This statement was confirmed in our experiments as well.Tetranychus urticae developed fastest on Phaseolus vulgaris (9.42 d), followed by Cucumis sativus (10.26 d) and Capsicum annuum (10.92 d). The largest differences in development time between hosts were recorded at 15°C, the differences at 20-25°C were small, and at 30-35°C they were almost identical. The largest difference in development time was recorded between P. vulgaris and C. annuum at temperatures of 15, 20 and 25°C; development on P. vulgaris was faster by 1.5 days. The difference was further confirmed by statistical analysis. The differences in the development of the mite on different ho...

Abstract:In 1995-2004 we investigated leaf rust virulence in Slovakia on Thatcher near isogenic lines (NILs) with genes Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr10, Lr11, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. According to reaction of leaf rust isolates resistance genes Lr9 and Lr19 were completely effective to all examined pathotypes in all years. The resistance genes Lr24 and Lr28 were also completely effective to all examined pathotypes till the year 2001. In the year 2001 we detected 20% and 10% virulent isolates on NILs Lr24 and Lr28, respectively. According to the reaction of investigated isolates from the territory of Slovakia on NILs, resistance genes Lr2c, Lr3a, Lr11, Lr17, Lr21, Lr23 and Lr26 were mostly ineffective. During the 1994-2004 period we detected 16 races of leaf rust (races 2, 2SaBa, 6, 6SaBa, 12, 12SaBa, 14, 14SaBa, 57, 57SaBa, 61, 61SaBa, 62SaBa, 77, 77SaBa, 77/57SaBa). The most frequently determined races were 61SaBa and 77SaBa, which occurred in all years. Among frequently determined races we can assign race 12SaBa as well. According to the field tests in 2001-2004 good resistance to leaf rust was displayed by the cvs Arida (Lr13, Lru), Eva (Lr3, Lru) and Solara (Lru).

Abstract:In 2009-2011 virulence of the wheat leaf rust population was studied on Thatcher near-isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3a, Lr9, Lr11, Lr13, Lr15, Lr17, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28. Samples of leaf rust were obtained from different parts of the Slovak Republic. A total of 122 wheat leaf rust isolates were analysed. Resistance gene Lr19 was effective to all tested isolates. Virulence to Lr9 was found, however only in one isolate. Gene Lr24 conditioned resistance to almost all rust collections. A lower frequency of virulence to Lr2a and Lr28 was also observed. Nineteen winter wheat cultivars grown in Slovakia were tested with 8 leaf rust isolates. Winter wheat cultivar Bona Dea was resistant to all isolates applied in the greenhouse test. Presence of Lr genes was estimated according to the reactions of the tested cultivars. Presence of Lr10, Lr26, Lr34 and Lr37 was studied by molecular markers.

Abstract

In 1997–1998 virulence of the leaf rust population was studied on near isogenic Thatcher lines with the genes for resistance Lr1, Lr2a, Lr2b, Lr2c, Lr3, Lr9, Lrll, Lr15, Lr/7, Lr19, Lr21, Lr23, Lr24, Lr26 and Lr28, and on the standard differentials Mala­ koff, Carina, Brevit, Webster, Loros, Mediterranean, Hussar, Democrat and the supplemental cultivar Salzmtinder Bartweizen. All 55 analyzed rust samples were avirulent on Lr9, Lr19, Lr24 and Lr28.On the standard differentials, races 61SaBa, 77SaBa, 77/57SaBa, 2SaBa, 77, 12SaBa, 62SaBa, 6, 6SaBa and 14 were determined. Races 61SaBa and 77SaBa (77/57SaBa) prevailed in both years. Races 6 and 6SaBa were found for the first time. The effectiveness of leaf rust resistance genes in registered cultivars under field conditions in variety trials is discussed.