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The trials were carried out over the period 1999-2000 with a view to testing the efficacy of reduced doses of triazole fungicides on winter wheat cv. Zentos. Septoria diseases (Septoria spp.) occurred on winter wheat annually. Full and reduced dosages of fungicides were highly effective against Septoria leaf blotch at an early milk stage, especially on flag leaf. Later the efficacy of reduced dosages of the fungicides was lower, than that of full doses. Due to full dosage of fungicides we obtained a sufficient yield increase annually. The yield increase through the use of 3/4 reduced doses was lower. But yield increase through reduced dosage to 1/2 was low and insufficient.

In 1997-1998 virulence of the wheat leaf rust population was studied on Thatcher near isogenic lines with Lr1, Lr2a, Lr2b, Lr2c, Lr3. Lr9, Lrll, Lrl5, Lrl7, Lrl9, Lr21, Lr23, Lr24, Lr26 and Lr28. On these NILs 11 pathotypes were determined in 1997, and 8 inl998. All rust samples were avirulent onLr9, Lr19, Lr24 and Lr28.There was a relatively low frequency of virulence on Lrl, Lr2a and Lr2b. Most rust samples were virulent on Lr2c, Lr11, Lr15, Lr17, Lr23 and Lr26. All samples were virulent on Lr3 and Lr21. The identified pathotypes conformed with races 61SaBa*, 77SaBa, 2SaBa, 12SaBa, 57SaBa, 6SaBa, 61*, 77 and 6. Races 61SaBa*, 77SaBa and 2SaBa prevailed in 1997, races 61 SaBa*, 77SaBa and 12SaBa were prevalent in 1998. Races 6 and 6SaBa were found for the first time. Data on Lr genes in recently registered winter wheat cultivars are presented.

The bionomics of Acarus siro was studied at 18 and 20°C and 70 and 80% R.H. on wheat germs, linseed, rapeseed and sunflowers to obtain data for optimisation of biological control of stored product mites on oilseeds. Wheat germs were used as a control substrate as they were considered optimal for development of A. siro. The development of eggs and larvae was longer than that of protonymphs and tritonymphs. Wheat germs appeared to be a better substrate for the development of mites than oilseeds. Generally, the life span of females as well as the oviposition period was shortest on wheat germs while longest on sunflower; also, at the higher temperature the female life span was shorter. The maximum number of eggs laid by a single female (356) was recorded on wheat germs at 20°C and 80% R.H. The development was significantly shorter at 20°C than at 18°C regardless of humidity. There were no significant differences between the effects of the tested oilseeds.

During 1997-1998, the reaction of the collections of winter and spring wheat varieties to Tilletia caries was determined. In both years the most diseased winter varieties were Simona and Sparta, the least diseased were Samara and Ilona. High variability in the level of infection was observed in some varieties (VIada, Estica, Regina, Vega). No winter wheat variety was completely resistant. The most diseased spring wheat variety was Alexandria in both years, while Grandur showed no infection. High variability in the level of infection was observed in the special trials with cv. Ina and Contra. In trials of the efficacy of seed dressing against T. caries and T. laevis there was variability only in the controls, but not in dressed variants.