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Perennials

Winter annual weeds generally emerge in the fall of the year, go dormant over winter, resume active growth in the spring, flower and set seed before dying in the summer.  Winter annual weeds are generally most susceptible to herbicides in the fall or before they have begun to bolt or joint in the spring.  Winter annual weeds are usually the most abundant type of weeds in winter wheat because they have a similar life cycle.

Summer annual weeds germinate in the spring and complete their life cycle during the summer.   Germination of summer annual weeds is a function of soil temperature and varies by species.  The summer annual weeds that are most troublesome in wheat tend to be those species that germinate very early in the spring, such as kochia, Russian thistle, and wild buckwheat.  Summer annual weeds tend to be most serious when you have thin wheat stands and late wheat canopy development in the spring.

Perennial weeds reproduce vegetatively and can live indefinitely.  Perennial weeds are often patchy in nature depending on where the weed first became established in the field.  Perennial weeds are difficult to control and often require a persistence weed management program to get them under control.

For more detailed information on weed control and herbicide use, consult the KSU Chemical Weed Control Guide.  Always read and follow label directions before using any pesticide.