Downy brome (Bromus tectorum L.), jointed goatgrass (Aegilops cylindrica Host), and volunteer cereal rye (Secale cereale L.) are winter annual grass weeds that are increasingly troublesome in the winter wheat (Triticum aestivum L. emend. Thell.)-fallow rotation areas of the western USA. Six dryland cropping systems—continuous no-till winter wheat, winter wheat-fallow with fall tillage, winter wheat-fallow with fall applied herbicide, winter wheat-fallow-fallow, winter wheat-sunflower-fallow, and winter wheat-proso millet-fallow—were compared for their effect on winter annual grass densities in winter wheat. Winter annual grass densities averaged 145, 4.4, and 0.4 plants/sq yard for the 1-, 2-, and 3-yr systems, respectively. Eradication of the winter annual grasses was not achieved with any of the systems. Dockage and foreign material levels in wheat grain were lower in 3-yr than in 2-yr cropping systems. Jointed goatgrass was the most persistent annual grass investigated. The ProblemDowny brome, jointed goatgrass, and volunteer cereal rye are increasingly troublesome winter annual grass weeds in the winter wheat-fallow rotation areas of the USA. A 1989 mail survey of Colorado farmers indicated that these three weeds infested over 1.3 million acres of cropland in the state. The estimated cost of these infestations to Colorado wheat growers was over $20 million annually. Herbicides are not available to provide selective control of these grasses in winter wheat. Chemicals and tillage control these weeds during the fallow period, but sufficient seed usually remains to reinfest the following winter wheat crop. Crop rotation may be an effective way to control these weeds in winter wheat, but few reports exist of the effects of cropping systems on these weeds. Literature SummaryDowny brome at densities of 20, 33, and 54 plants/sq yard reduced winter wheat yields by 10, 15, and 20070, respectively, when plants emerged within 14 d of winter wheat. Jointed goatgrass at 15 plantslsq yard reduced winter wheat yield in Colorado by 27 and 17% when emerging 0 and 6 wk after winter wheat, respectively. In addition to reducing winter wheat yield, jointed goatgrass also lowered grain quality by increasing dockage or foreign matter. In Oregon, 162 rye plantslsq yard reduced winter wheat yield by 33% when rye was removed in February compared with 69% when not removed. Jointed goatgrass spikelets and rye seed are serious contaminants of winter wheat grain. The longevity of downy brome seed varies widely. Freshly harvested downy brome seed exhibit a rapid and high germination percentage, suggesting that all viable seed will germinate when conditions are suitable. Viable seed were reported 5 yr after burial, however. Jointed goatgrass seed persists in undisturbed soil from 3 to 5 yr depending on site conditions. By the third year, less than 8% of seed buried 2 in (5 cm) deep survived. All seed were nondormant 3 yr after burial. The period of greatest jointed goatgrass seed loss from soil coincided with peak emergence in the fall. Less than 1% of rye seed was viable 3 yr after burial. Study DescriptionField experiments were conducted at the High Plains Agricultural Lab northwest of Sidney, NE, at an elevation of 4270 ft above sea level. Soil type: Duroc loam Cropping systems: Continuous winter wheat (no till) Winter wheat-fallow with fall sweep tillage Winter wheat-fallow with fall applied atrazine at 1 lb ai/acre Winter wheat-fallow-fallow Winter wheat-sunflower-fallow Winter wheat-proso millet-fallow Check—winter wheat-fallow with fall sweep tillage and no weeds Each of the above main plot treatments was divided into three sub-plot treatments: Downy brome Jointed goatgrass Volunteer cereal rye Herbicides used: Landmaster BW, a mixture of glyphosate (Roundup) and 2,4-D amine, after wheat harvest except in cropping system 2 Atrazine in late August after wheat harvest in cropping systems 4 and 6 Glyphosate prior to wheat seeding in cropping system 1 and in first year of fallow in system 4 Pendimethalin (Prowl) preplant incorporated before sunflower in system 5 2,4-D low volatile ester in wheat for all cropping systems Cultivars planted: Winter wheat—‘Arapahoe’ Proso millet—‘Sunup’ Sunflower—‘Dahlgren 855’ Applied QuestionTo what extent can crop rotation reduce winter annual grass weed pressure in dryland winter wheat production? None of the three winter annual grasses were eradicated with the cropping systems studied in this research. In 1993, when environmental conditions did not promote winter annual grass germination in the winter wheat crop, no difference between 2- and 3-yr systems were observed. The winter annual grass weeds thrived in the continuous winter wheat system in both 1993 (data not shown) and 1994 and made wheat production impossible (Table 1). Higher weed densities in 1994 resulted in more treatment differences. Weed densities in the 2-yr systems were about 3% of those in the continuous wheat system. Weed densities in the 3-yr systems were just 10% of the levels in the 2-yr systems. Jointed goatgrass was the most persistent of the three weeds studied, and crop rotations may have to be longer than 3 yr if a heavy infestation of jointed goatgrass is present. No difference in winter annual weed densities was observed between the two 2-yr systems or the three 3-yr systems. Winter wheat yields were not affected by the cropping system. RecommendationThe introduction of a late spring-planted crop into the winter wheat-fallow system can reduce winter annual grass weed densities by over 90%. While no 3-yr system eliminated winter annual grass weeds, grade reduction and dockage of grain due to jointed goatgrass and rye contamination were reduced. Timing of fallow tillage and chemical treatments is critical to all systems. Prevention of annual grass seed production during fallow is critical to the success of these systems. The 3-yr systems allow more opportunities to recover from mistakes and environmental conditions that permit winter annual grass weeds to produce seed. Table 1Effect of dryland cropping systems on winter annual grass densities in winter wheat at Sidney, NE, in April 1993 and 1994. Weed DooulationCropping system†Downy bromeJointed goatgrassRYeAll weeds-------------------plantslsq yard----------------CW176 109 148 145 WW-Ft0.18.62.23.6WW-Fh0.211.83.75.3WW-F-F0.11.40.10.5WW-SF-F0.20.70.20.3WW-PM-F0.30.90.10.4†Cropping system abbreviations: CW, continuous no-till winter wheat; WW-Ft. winter wheat-fallow with fall tillage; WW-Fh, winter wheat-fallow with fall herbicide; WW-F-F, winter wheat-fallow-fallow; WW-SF-F, winter wheat-sunflower-fallow; and WW-PM-F, winter wheat-proso millet-fallow.

In the experiment the authors investigated the influence of progressive participation of winter wheat in crop rotation on its sanitary condition. Depending on the rotation of crops the different levels of infestation winter wheat by main fungi (eyespot, powdery mildew, septoria leaf blotch, glume blotch, brown rust) was observed. Lowest yield of grain was obtained from rotation of winter wheat - sugar beet - winter wheat and the highest one from the rotation of field bean - sugar beet - winter wheat

In long-term investigation of weed of winter wheat and spring barley stands investigation in Central and Eastern Bohemia great differences in weed infestation by some weed species were recorded in different years in dependence on forecrops. In investigated winter wheat stands the occurrence of fertile stems of coach grass much varied and the most occurred in wheat stands cultivated after clover crops, above all, after sugar beet, potatoes, and winter rape as well. In spring barley stands the coach grass appeared much less. The highest incidence was recorded after cereals as forecrops, especially after winter wheat, basically, it did not occur after sugar beet. Marked differences were achieved in the occurrence of fertile panicles of coach grass between stands of winter wheat and spring barley , greater weed infestation was in spring barley. The coach grass occurred least in winter wheat cultivated after clover crops, but also after winter rape in the crop rotation: winter barley, winter wheat. In winter barley coach grass appeared the most if it was cultivated after cereals as forecrops, especially spring crops, but also on heavier soils and after sugar beet and silage maize. In investigation of weed infestation of stands of winter and spring cereals literary data have been confirmed on significantly higher representation and greater production of generative organs in silky bent grass, bedstraw, and scentless mayweed in winter wheat stands than in spring barley stands regardless of the forecrop.

In the paper the results of 16 years investigation on uptake of magnesium by winter wheat (cultivated in 5 longterm crop rotation experiment) were presented. Magnesium uptake by winter wheat was lower on control (without NPK) in comparison with full mineral fertilization. The differences in uptake magnesium on soils with high content of available Mg was particularly big. It gives the evidence of synergistic influence of NPK fertilization on winter wheat nutritive state with magnesium

During 1989-92, the winter cereals: wheat, triticale, barley and rye were cultivated after-leguminous crops, oat and wheat or rye, on soil complexes 2.4 and 5. The highest yield of all cereal species were recorded after leguminous plants and the lowest after wheat and rye. The decline of the yield of rye and triticale grown after cereals was about 10%, but yield decrease of wheat and barley was almost 20%. Response of winter cereals on forecrop has increased according to deterioration soil condition. Independently on soil complex, winter triticale was the highest yielding cereal

The effect of herbicide and urea-ammonium nitrate (UAN) combinations on winter wheat injury in absence of noncompetitive weeds and weed control during a winter wheat-fallow and a winter wheat-sorghum-fallow rotation were investigated. Winter wheat was planted at different dates to obtain different growth stages for spraying in the spring. Winter wheat produced greater grain yields when planted Sept. 15 or Sept. 25, 1987, 1988, and 1989 vs. Sept. 1 at North Platte, NE, while at Sidney, NE, grain yield was higher in wheat planted on Sept. 10 or Sept. 20, 1988, compared to Aug. 26. Spring-applied UAN increased grain yield on wheat planted Sept. 10 compared to no UAN in 1988-89 at Sidney, but not in 1987-88, while at North Platte, grain yields were not affected by UAN. At Sidney 2,4D ester at 0.6 kg ae ha-1, 2,4-D amine plus dicamba at 0.3 plus 0.1 kg ae ha-1, metsulfuron at 0.007 kg ai ha-1 plus 0.25% nonionic surfactant (NIS), and metsulfuron plus 2,4-D ester at 0.007 plus 03 kg ha-1 plus NIS decreased grain yields compared to one handweeding. At North Platte in 1988-89, when UAN was applied with 2,4-D ester, 2,4-D amine plus dicamba, or metsulfuron plus 2,4-D plus NIS grain yields were reduced compared to the handweeded check on wheat planted Sept. 15. Occasionally, metsulfuron plus 2,4-D ester plus NIS treated wheat yielded less grain than metsulfuron plus NIS treated wheat. One or more herbicide treatments reduced wheat grain yields 4 of 15 application dates. Crop injury was related to growth stage and health of winter wheat when treatments were applied. Wheat under stress was more susceptible to herbicide damage than healthy wheat. Metsulfuron and metsulfuron plus 2,4-D controlled kochia, tumble thistle, and redroot pigweed better after wheat harvest than 2,4-D or 2,4-D plus dicamba at North Platte, but allowed summer annual grass weeds to grow.

The effect of herbicide and urea-ammonium nitrate (UAN) combinations on winter wheat injury in absence of noncompetitive weeds and weed control during a winter wheat-fallow and a winter wheat-sorghum-fallow rotation were investigated. Winter wheat was planted at different dates to obtain different growth stages for spraying in the spring. Winter wheat produced greater grain yields when planted Sept. 15 or Sept. 25, 1987, 1988, and 1989 vs. Sept. 1 at North Platte, NE, while at Sidney, NE, grain yield was higher in wheat planted on Sept. 10 or Sept. 20, 1988, compared to Aug. 26. Spring-applied UAN increased grain yield on wheat planted Sept. 10 compared to no UAN in 1988-89 at Sidney, but not in 1987-88, while at North Platte, grain yields were not affected by UAN. At Sidney 2,4D ester at 0.6 kg ae ha-1, 2,4-D amine plus dicamba at 0.3 plus 0.1 kg ae ha-1, metsulfuron at 0.007 kg ai ha-1 plus 0.25% nonionic surfactant (NIS), and metsulfuron plus 2,4-D ester at 0.007 plus 03 kg ha-1 plus NIS decreased grain yields compared to one handweeding. At North Platte in 1988-89, when UAN was applied with 2,4-D ester, 2,4-D amine plus dicamba, or metsulfuron plus 2,4-D plus NIS grain yields were reduced compared to the handweeded check on wheat planted Sept. 15. Occasionally, metsulfuron plus 2,4-D ester plus NIS treated wheat yielded less grain than metsulfuron plus NIS treated wheat. One or more herbicide treatments reduced wheat grain yields 4 of 15 application dates. Crop injury was related to growth stage and health of winter wheat when treatments were applied. Wheat under stress was more susceptible to herbicide damage than healthy wheat. Metsulfuron and metsulfuron plus 2,4-D controlled kochia, tumble thistle, and redroot pigweed better after wheat harvest than 2,4-D or 2,4-D plus dicamba at North Platte, but allowed summer annual grass weeds to grow. Yields of grain sorghum planted after a 10-mo fallow period were higher following winter wheat treated with three of four herbicides than the handweeded treatment.

The results of field trials were collected from three experimental agricultural stations since 1977 to 1991. In all stations wheat grown after gave lower yield than after potatoes. The yield of winter wheat grown after oats was similar to the yield of winter wheat grown after potato. The spring barley yield differed in years and stations and depended on the forecrop. In 1978-81, spring barley grown after itself and after winter wheat yielded significantly lower than after potatoes

The object of the study was to determine the effects of rotation length, forecrops and the intensity of crop production on winter wheat, growing on very good alluvial soils in Zulawy region. It was found that high forecrop requirements of winter wheat also concern very good and good wheat soils. Chemical control of weeds and fungi diseases in wheat plantations result in yield increases

The best doses of nitrogen for the two grains, as well as the productivity of water and nitrogen unit were determined. Triticale gave a higher yield than wheat; sprinkling irrigation had increased the yield of winter wheat by 40 and triticale by 15 percent, whereas the nitrogen fertilization by 104 and 131 percent respectively. The interaction of the both treatments had increased the yield of winter wheat by 198 and triticale by 157 percent. On irrigated fields a dose of 100-125 kg N/ha is sufficient. The productivity of 1 kg N applied on watered winter wheat plots was by 37.5 percent higher than on control ones; in case of triticale it was higher by 33 percent