The attack of pests and diseases on main shoots and tillers of spring wheat (1981) and winter wheat (1983/84) was compared. Erysiphe graminis f. sp. tritici was more frequent and severe on the tillers than on the main shoots. Disease intensities of tillers later formed were higher than those on earlier ones. In winter wheat, Septoria nodorum incidence and severity were higher on main shoots than on tillers. In spring wheat, Sitobion avenae was more frequent on main shoots.1157 In contrast to winter wheat, the main shoots and early tillers of spring wheat were attacked both more severely and frequently by Metopolophium dirhodum than the tillers later formed. Possible reasons for the differences between the main shoots and the tillers as well as their influence on sampling procedures used for pest and disease assessment are discu

The four-year exact field experiments with spring and winter wheat have proved that variable plu1546vio-thermal conditions in particular years exert a significant effect on the yield increments. Sprinkler irrigation led to a considerable increase of mean yields of crops: spring wheat - by 29%, winter wheat - by 20%. The highest yield increments were recorded in the Kaspar and Kolibri, Jana and Grana varieties. Fertilization resulted in a significant increase of the mean yield of spring wheat varieties (by 29%) and of winter wheat var. (by 33%). The Drabant var. gave the highest (40%) mean yield increment under the fertilization effect although the yield of this variety in particular fertilizing treatments was lower than that of other varie

Livestock grazing of cereal grain crops during the early portion of their growing cycle is practiced to some degree in many parts of the world. While a substantial body of literature relating grain yields to defoliation practices has been accumulated, most of this work lacks detail concerning the effects of grazing on individual components of plant yield. Reports of grazing effects on grain yield have been quite variable, ranging from substantial decreases to modest increases in grain yield. Understandably, many grain producers are confused about the exact impact that livestock grazing has on their grain crop. The effects of a single intense March-grazing by sheep, on the components of biomass yield in 'Yamhill' soft white winter wheat (Triticum aestivum L. em Thell.) were evaluated near Corvallis, OR, during the 1979-to-1981 harvest years. Grazing increased total plant biomass yield each year. The greatest increase was in the grain component, which averaged 16% greater on grazed than on ungrazed plots 'during the 3 yr of the study. Contrary to widely held opinion, grazing had no effect on the number of fertile flower heads produced by the crop. Likewise, grazing did not affect either the number of seeds produced per spikelet or the average seed weight. Increased grain yield on grazed plots largely resulted from an increased number of fertile spikelets produced per wheat head on those plots. These data suggest that components of wheat grain yield that are determined prior to tiller elongation may respond to grazing management.