Feral rye (Secale cereale L.), also known as volunteer or cereal rye, is a troublesome weed in winter wheat production in the low and intermediate rainfall zones of eastern Washington and Oregon and southern Idaho. Rye has been grown in the Pacific Northwest (PNW) for seed and cover, as well as for forage in hay production systems, pastures, and range. It has also been used in wildlife and soil conservation seed mixtures. Regional weed scientists think our current feral rye management problems in winter wheat originated when rye plants used for these other purposes escaped into cultivated fields. Since then, feral rye plants with the most “weedy” characteristics (for example, early seed shatter and long seed dormancy) have thrived in the winter wheat–fallow rotations of the region (Figure 1).
Feral rye persists as a weed because it typically matures, and most of its seed shatters, before winter wheat harvest. The presence of feral rye in wheat grain may result in dockage and other losses in wheat quality leading to grade reduction. Millers and bakers avoid buying wheat contaminated
Feral rye and winter wheat are both winter annual grasses that reproduce by seed. Feral rye may germinate as late as mid-April and still have sufficient cold weather to vernalize (that is, promote flower development through exposure of young plants to cold temperatures) and produce seed. Feral rye resembles winter wheat in habit, but may be differentiated from wheat by several characteristics (Table 1, Figures 2–6).
In eastern Oregon, feral rye populations of 18 plants per square foot reduced winter wheat yield by 33 percent when allowed to compete with winter wheat until February, and 69 percent when allowed to compete with winter wheat until grain harvest in July (Rydrych 1977). In northeastern