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Methodology – Weed Counts
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same person as the preselected quarter section. Producer responses to the qualifying questions were recorded in a
Microsoft ® Access form; as well the following information for qualified fields:
(a) the name, mailing address, and telephone number of the farm operator for the qualified fields,
(b) a new quarter section if it had been changed from the preselected site,
(c) the crop seeded in the selected field,
(d) the number of acres in the selected field.
If the list was exhausted without qualifying the required number of fields, an additional list of randomly selected
sites was generated.
Field Survey Personnel and Orientation Sessions
The fields were allocated to survey personnel by the Agricultural Fieldmen in each county or municipal district. In
some cases the Agricultural Fieldmen opted to hire a contractor to carry out the survey; however, in most cases the
task was carried out by county weed inspectors or other temporary staff. Training material was provided to each
county office and the Agricultural Fieldmen were asked to insure that their staff understood the material and was
competent to correctly carry out the survey. Alberta Agriculture and Rural Development provided additional
training on a regional basis in conjunction with the training offered to weed inspectors.
Timing of Weed Counts
Weeds that had not been controlled in the fields were counted in the summer survey (July 7 to August 13). This
time was chosen for several reasons. The weeds in the field were, in part, a result of the agronomic management
decisions (e.g., crop rotation; time and type of tillage; rate and placement of fertilizer; selection, rate and
effectiveness of herbicide used) made by the farm operator at various times during the crop year. The impact of
these agronomic practices on the weed flora was reflected in the summer survey. Counts at this time of the year
showed the size and extent of troublesome weed populations. This survey time had additional advantages.
Identification was simplified because most of the weeds were mature. In particular, wild oats and other grassy
weeds had flowered or produced fruit and were easily recognized. Also, the field crew had more time to work on
the survey during the summer than during the period immediately after crop seeding.
Weed Counts in Fields
Once a surveyor arrived at a qualified field, the weeds were enumerated using a set pattern. The surveyor walked
100 paces along the edge of the field, turned at right angles, and walked 100 paces into the field. The inverted W-
pattern began at this point (Figure 5). Five locations were sampled along each arm of the pattern, giving a total of
20 locations. Locations were 20 paces apart. The number of individuals of each weed species was determined in a
0.25 m
2
quadrat (50 cm by 50 cm) at each of the 20 locations. The procedure was modified when necessary to
compensate for sloughs, odd-shaped fields and other irregularities.
100 paces
100 paces
5
1
10
15
20
20 paces
Figure 5.
W pattern used for field counts.