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Pest Status
Background
Chapter 42
Silene cucubalus Wibel, Bladder Campion
(Caryophyllaceae)
M.O. MAW
Silene cucubalus Wibel is a deep rooted perennial of Eurasian origin. It is spread by seed
(as many as 20 000 per plant) as well as vegetatively by parts of the root crown severed
by implements. It is resistant to the common herbicides 2,4-D (2,4-dichlorophenoxyacetic
acid) and MCPA (4-chloro-2-methylphenoxyacetic acid) at rates which can be
safely used in grain crops. The weed grows in waste places, roadsides, and railyards,
and although it is an infrequent weed in cultivated ground (Boivin 1968), it can be
troublesome in well drained pastures, cereal crops, and hay. It is found in the northeastern
and central United States and in every province of Canada to latitude 54°N
(Scoggan 1978) and is more common in the eastern than in the western parts of its range
(Frankton et al. 1970).
Although the weed is generally not a great problem throughout its Canadian range,
there are localized areas where it causes concern. For example, in the Ethelbert district
of Manitoba, a survey of weeds in cultivated fields (Thomas 1978) showed it to be
present in 25% of the samples in 50% of the fields surveyed with a mean density of 5.9
plants per square meter. In contrast, the weed was reported in only one of the remaining
38 Manitoba districts surveyed. and there it was found only in 0.4% of the samples in
8.3% of the fields at a density of 0.6 plants per square meter.
Although it would seem that there has been little change in the status of the weed on
cultivated lands since the 1966 survey (Alex 1966), agricultural practices have altered
the situation in areas such as in southeastern Manitoba. Here a shift has been away from
annual tillage to establishment of pastures and forage crops and forage seed production.
Where bladder campion was not a problem as recently as three years ago, it now is a
concern in over 4200 hectares and only limited control is being provided by herbicides
and cultural methods.
Surveys of the European insect fauna on species of Silene and Melandriwn were made
by the Commonwealth Institute of Biological Control (Miotk 1973). Sixty-six percent of
the phytophagous insects on the two genera were oligophagous and the supposedly
stenophagous species were either weevils or noctuids.
The chrysomelid, Cassida azuna Fab. (mistakenly identified as Cassida hemisplwerica
Hbst.) (Maw & Steinhausen 19800. 1980b), was collected in Switzerland and screened in
Canada (Maw 1976). The Cassidinae are generally specialized in their feeding habits and
species in a subfamily are usually restricted to a limited group of plants. This was found
to be so with C. azurea.
First instar larvae fed on all the plants in the tribes Sileneae and Alsineae tested but
they developed only on S. cucubalus. S. cserei. S. glauca. S. noctiflora. S. maritima, S.
alba, S. acau/is, Gypsophila repens, Dianthus chinensis .. and D. plumarius. Damage by
young larvae is confined to the epidermis of the leaf. while older larvae and adults eat
large holes in the leaf blade. Flowers of Silene are eaten by both larvae and adults.
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