Agriculture Reference
In-Depth Information
for “seeing” results in accordance with the standard conventions and
results of fi eld trials. This interplay of different representations of the fi eld
makes environmental problems more diffi cult to address and represent
through fi eld trials.
As a fi nal instance of the intermingling of trust, numbers, and visualiza-
tion in fi eld trials, I examine a case that was very much about “seeing” the
results of the fi eld trial. This case did have a kind of census of pest pressure
through numbers and also brought in the issue of trust. In all, this fi nal
example depicts very clearly the negotiations that take place over land and
its representation through fi eld trials.
The case concerned attempts to control a disease called lettuce drop,
caused by the
Sclerotinia
fungus. Affected plants droop and lie fl at on the
ground instead of forming round heads of lettuce. Lettuce plants infected
with
Sclerotinia
are generally unmarketable, and therefore the disease can
cause considerable losses. In the early 1980s an advisor (now retired) who
specialized in agricultural machinery and engineering began testing a tech-
nique called deep plowing for controlling
Sclerotinia
on lettuce. Deep
plowing requires a special plow that, at the time, was imported from
Europe and was quite expensive to purchase or rent. Deep plowing works
by turning the soil upside down, replacing the topsoil with 20 or so inches
of the soil below it. This turning is intended to take the upper levels of the
soil, where the disease is more prevalent, and replace it with the lower
levels, where there is less sustenance for the
Sclerotinia
pathogen. The deep
plowing leaves giant clods of soil in the fi eld that have to be broken up,
and growers have to replow the fi eld several extra times. Based on the
novelty of the idea, the advice and research of the advisor, and widespread
damage from the disease, many growers in the valley began using this
technique in an attempt to control lettuce drop.
About ten years later, in the early 1990s, the UC assigned an extension
specialist in plant pathology to work at a USDA research facility in Salinas.
During my fi eldwork in Salinas, I spoke to this specialist, and he described
one of his earliest research interests when he arrived in the area, the use
of deep plowing to control
Sclerotinia
on lettuce. After ten years of using
the special plow, he said, growers were still seeing mixed results and were
puzzled. The principle seemed sound, but they were not getting the kind
of control they had expected. Further, because the plow is expensive and
the technique involves a lot of time spent on plowing and replowing a
