Weed management: a need for ecological approaches - Ecological Management of Agricultural Weeds - page 24

substantial: more than 100% above conventional prices for broccoli in
California (Franco, 1989); 33% to 38% higher for apples in California (Swezey
et al ., 1994); and 45% to 119% higher for maize, 95% to 223% higher for
soybean, 28% to 94% higher for oat, and 46% to 74% higher for wheat in South
Dakota (Dobbs & Pourier, 1999). Substantial price premiums are also paid in
many European countries for organic products (Padel & Lampkin, 1994) and
are a major factor driving organic production of certain tropical products,
such as coffee.
In a review of data collected by land-grant universities comparing conven-
tional and organic grain and forage production in the midwestern USA
(including the South Dakota studies cited previously), Welsh (1999) con-
cluded that organic systems that receive price premiums at existing market
levels can consistently match or exceed the profitability of most common con-
ventional systems. Welsh (1999) also found that “break-even” premium levels
required for organic systems to match the profitability of conventional
systems were lower than the average premiums available during the 1990s. In
contrast,Klonsky & Livingston (1994) compared the economic performance of
different tomato-based cropping systems in California and found that net
returns from a conventionally managed two-year rotation were greater than
returns from an organically managed four-year system, even when available
organic premiums were included in the analysis.
These and other studies indicate that organic production is a viable means
of increasing farm profitability for some,but not all,farmers.Owing to a long-
standing paucity of weed research relevant to organic farming systems,strate-
gies to improve weed management are among the top research priorities of
organic farmers (Organic Farming Research Foundation, 1998). Ecological
approaches for weed management need to be fully developed to achieve the
agronomic and economic potentials of organic farming systems.
Transitions to ecological weed management
Characteristics and benefits of a systemic approach
Concerns over pesticide resistance,environmental and health hazards
of pesticides,and declining profitability are not unique to weed management.
Such problems have been recognized for several decades in the management
of arthropod pests and plant pathogens and led in the 1960s and 1970s to
development of the concept of integrated pest management (IPM). The IPM
concept has never been fully implemented for managing weeds,but its useful-