- Marah oreganus, a perennial, belongs to the Cucurbitaceae family
and it is commonly known as wild cucumber. In the past, this plant
grew along fence rows, but now wild cucumber has become a weed
problem in perennial grass seed fields of western Oregon. Several
research studies were conducted to examine the biology of the weed
and to observe the response to herbicide applications.
Two experiments were conducted to determine if the dormancy of
wild cucumber seed was due primarily to the effect of the seed coat
and/or a chilling requirement. Results of this study indicated that
dormancy can be broken by chilling and was not the result of seed
coat impermeability. There is a minimum time that wild cucumber
seeds must be exposed to cold temperatures before dormancy is broken.
In this research, 22 days at constant 5 C was insufficient to break
dormancy. Complete germination was obtained when seeds were kept at
constant 5 C, and were covered with moistened, but not saturated,
peat moss for 58 days.
Other experiments in the greenhouse were conducted to examine the response of seedling wild cucumber to herbicides and to develop
a technique for growing seedling wild cucumber under controlled
conditions. Preliminary trials using garden cucumber (Cucumis
sativus) as an indicator plant were used to determine herbicide
rates for subsequent experiments. This study indicated that
picloram and phenoxy herbicides did not cause necrosis on seedling
wild cucumber but were most effective as growth inhibitors. Treatment
with 2,4,5-T at 0.14 kg/ha caused more severe reduction in dry
weight than with 2,4-D at 4.48 kg/ha. Glyphosate at 0.28 kg/ha was
the only herbicide tested that caused necrosis to the leaves and inhibited
growth of wild cucumber. DPX-4189, fosamine, and Dowco 290
did not induce any visual symptoms, although reductions in growth
from the check 12 days after treatment were observed.
Two field trials were conducted to evaluate the control of
established wild cucumber plants. Evaluations were made over a
2-year period in the same plots. During the treatment year (1980),
only two herbicides controlled wild cucumber at a level that would
be commercially acceptable. The herbicides most effective for this
purpose were glyphosate (2.24 or 3.36 kg/ha) and 2,4,5-T (0.84, 1.68,
or 3.36 kg/ha). At one location, wild cucumber plants treated in
1980 with glyphosate and 2,4,5-T did not show regrowth in spring or
summer, 1981. The other location was accidentally destroyed and no
valid regrowth data were collected.