The Rural Voice, 1987-12, Page 30b•
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28 THE RURAL VOICE
AGRICULTURAL RESEARCH
The Good, the Bad, the Ugly,
and the Incomprehensible
PART TWO
by Ian Wylie -Tool
In 1976, the Manitoba strawberry
crop was attacked by a new pest, a
cutworm that bored into the crown of
the plants. The extensive damage
caused by this insect was new in North
America: nothing was known about
the insect's life cycle or habits, and no
control measures were known. Yet
within three years the life history of
the insect was mapped and effective
control was achieved, halting the
potential devastation of the Manitoba
strawberry industry.
In agriculture, this is an example
of good research, where the work has
direct, practical benefit for the farmer.
To achieve this practical end, the
research went through four distinct
phases: (1) assessing research pri-
orities, (2) conducting the research
program, (3) proposing control meas-
ures, and (4) testing the effectiveness
of control procedures.
The first stage was initiated on the
farm when growers noticed their fields
dying in an unrecognizable way. The
various experts called in to look at the
fields recognized the unique nature of
the damage, and passed the problem
on to scientists at the Agriculture
Canada Research Station in Winnipeg.
The insect was identified and a
search made through research liter-
ature to see what was known about its
life history and its pest status. The
search revealed that the adult moth
stage was widespread and common in
North America, but said nothing about
host plants or life cycle. The insect
was not recorded as a pest. After this
initial assessment, research priorities
became clear: to understand the life
cycle and develop a control program
based on that information. A scientist
who had worked on cutworms in the
past was assigned to the project.
The second stage, that of actually
doing the research in order to work
out the life cycle, followed standard
procedures. Life history research has
been done countless times and is
usually not difficult. In this case,
research began with the adult stage, as
the adults happened to be about when
the project was started.
Moths were collected and caged in
the lab with a potted strawberry plant.
They laid eggs on dead and dying
strawberry leaves and around the pot.
The eggs developed pigments that
indicated fertility, but did not hatch
after six weeks. This information
suggested that the moths laid eggs in
the straw and dead plant matter that
surround strawberry plants, and that
the eggs overwintered and hatched in
the spring.
Further lab and field studies con-
firmed this. They also showed that the
early larvae fed briefly outside on
leaves before going into the leaf
petioles to feed. Larvae changed
petioles once or twice before leaving
them and boring into the crown of the
plant. After feeding for a total of nine
weeks, the larvae left the core and
pupated in the soil around the roots,
emerging three weeks later as moths.
Adult flight was limited, the females
mating and laying eggs in the same
field from which they emerged.
The life cycle information gener-
ated ideas for the third stage: propo-
sals for controlling the pest. Spraying
with insecticides would have to be
timed to coincide with the period
when the larvae left the leaf petioles
and moved into the crown. This was
the only time in the life cycle that
larvae were exposed and vulnerable to
spray. It was also proposed that the
plowing of old fields should be post-
poned until after the moths had laid
eggs in them. Plowing the field under
would kill the eggs, reducing the
number of larvae the next year.
The fourth stage, that of testing
the control procedures, showed these
measures to be effective. As the
scientist involved had worked very
closely with growers, the informal
progress of the research was known by