Knowledge, science, and practice in ecological weed management: farmer–extensionist–scientist interactions - Ecological Management of Agricultural Weeds - page 122

Figure 3.4 An illustrative yearly cycle for scientist collaboration with farmer
groups.The objectives are to observe field-scale weed presence and to analyze
farmer decision-making in the use ofweed control practices.
Methods to measure and study weeds
To link their different perspectives on weeds, farmers, extensionists,
and researchers need complementary methods to observe and quantify weed
species composition, abundance, and distribution. Few would disagree that
better quantification of weeds should lead to better management. Cousens &
Mortimer (1995, pp. 291-2) suggested that observations should have enough
precision to estimate current weed levels and predict trends. Similarly,
Firbank (1993) proposed that weed monitoring should capture differences in
order of magnitude. Hamilton (1995, pp. 101-4), in his study of adult learn-
ing methods with Australian grain farmers, concluded that observation
methods should place less emphasis on high accuracy. He suggested that
observation should facilitate group analysis of different situations by estab-
lishing relative magnitudes. With this type of observation, farmers more
readily extrapolated results to other fields or farms.
Research on methods for field level scouting in weed science has concen-
trated on the decision to apply post-emergent herbicides (Marshall, 1988;