Weed management: a need for ecological approaches - Ecological Management of Agricultural Weeds - page 30

Summary
Much of the last half-century of weed science and weed management
technology has been directed, implicitly and explicitly, at weed eradication. Is
this a realistic possibility in most arable fields, pastures, and rangelands? We
believe it is not, given the ecological similarities between weeds and the crops
they infest, the dispersal ability of many weed species, and the capacity of
most weeds to adapt rapidly to selection pressures imposed upon them (see
Chapter 10). Conventional efforts to eradicate weeds with herbicides have
reduced weed competition and improved farm labor efficiency, but have also
incurred substantial costs, including environmental pollution, threats to
human health, and growing dependence on purchased inputs. New
approaches are needed to manage weeds effectively while minimizing or elim-
inating such costs.
This chapter has introduced the concept of weed management systems that
are less reliant on herbicides and more reliant on ecological processes, such as
resource competition, allelopathy, herbivory, disease, seed and seedling
responses to soil disturbance, and succession. We call this concept ecological
weed management. Ecological weed management does not exclude the use of
herbicides, but minimizes their use through the creation of weed-suppressive
agricultural systems. Like conventional management systems, ecological
weed management will not eliminate weeds. However, as discussed in later
chapters, it has the potential to effectively reduce weed density, limit weed
competitive ability, and prevent undesirable shifts in weed community com-
position, while lowering the use of nonrenewable resources, minimizing
threats to human health and the environment, and providing a net benefit to
local and national economies.
In contrast to chemically based approaches, ecological weed management
has no shortlist of prepackaged, broadly applicable remedies. Instead, it relies
on biological information, multiple tactical options, farmer decision-making,
and careful adaptation of general design principles to site-specific conditions.
Farmers clearly assume a larger burden of responsibility for insuring success
when using ecological rather than chemical weed management systems. On
the other hand, the benefits of using an ecologically based approach may
include more durable weed suppression, cleaner air and water, and less
damage to nontarget organisms.Ecological farming may also promote greater
farm profits,through cost reductions and price premiums,and healthier rural
communities, through practices that are especially well suited to farms that
are family-owned and operated.
The development of ecological weed management systems is in its infancy.