Weed life history: identifying vulnerabilities - Ecological Management of Agricultural Weeds - page 84

Conclusions
The discussion in the preceding sections indicates that agricultural
weeds generally share certain properties, including small seed size, high rela-
tive growth rate, low early absolute growth rate, intolerance to stress, and
high reproductive capacity. They differ from crops in most of these respects,
and these differences form the basis for a variety of weed management tactics.
Despite similarities among weeds, weed species differ with respect to lon-
gevity, ability to spread vegetatively, temporal pattern of seed production, rel-
ative seed size,ability of seeds to persist in the soil,and season of germination.
Divergent life history characteristics allow different weed species to prosper in
differing sorts of crop production systems and may require divergent man-
agement strategies for successful control.
The several life cycle stages of a weed provide separate opportunities for
control. Constraining a weed population at several points in the life cycle by
using multiple partial controls is the essence of integrated weed management
and is the basic approach for meeting the objectives of weed management pro-
posed in Chapter 1.Chapters 4 through 9 discuss methods for attacking weeds
at various stages in their life cycle. Often, reduction in the number of individ-
uals passing through a stage improves management options in succeeding
stages. In some cases, a particular tactic may be quite impractical unless the
population is constrained in other ways as well. Consequently, the potential
effectiveness of a particular tactic may be much greater than is indicated by
studies that treat the factor in isolation.
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