Garden weeds - Principles of Horticulture - page 223

(a) (b)

Figure 17.22 (a) Horsetails have an extensive rhizome system; (b) horsetail emerging from soil

In turf, cultural control involving removal of the
deep root by a sharp trowel is recommended, but
this leaves bare gaps in turf for invasion by other
weeds. A product containing dicamba , MCPA and
mecoprop-P is effective, especially against young
dock plants. Glyphosate can be used for control
in such situations as bare soil and ornamental beds
containing woody perennials, and in cane fruit, but
not in green-stemmed crops. Great care is needed to
avoid spraying foliage of garden plants.

and has been lightly bruised , to allow better spray
entry through the thick waxy epidermis . Great care is
needed to avoid spraying foliage of garden plants.

17

Mosses

Moses (that belong to the division Bryophyta) include
three species that may be important weeds in gardens.
The small cushion-forming moss ( Bryum spp.) grows
on sand capillary benches in greenhouses, and in acid turf
that has been closely mown. Feathery moss ( Hypnum
spp.) is common on less closely mown, unscarified turf,
or on the compost surface in pot plants (Figure 17.23).
A third type of moss ( Polytrichum spp.), which looks
quite different from the other two species, is erect and
has a rosette of leaves. It is found in dry acid conditions
around golf greens. Cultural methods such as improved
drainage, aeration, liming, application of fertilizer and
removal of shade usually achieve good results in turf.
Control with contact scorching chemicals (e.g. ferrous
sulphate ), applied in spring or summer may give
temporary results. Moss on sand benches becomes
less of a problem if the sand is regularly washed.

Horsetails

Horsetails (that belong to the order Equisetales) are
related to ferns. They have a more complex structure
than mosses and liverworts (see p. 52). One species,
the field horsetail ( Equisetum arvense ), may be a
serious weed in turf, soft fruit and in nursery stock
(Figure 17.22), and especially in damp soil situations.
Its roots produce persistent rhizomes (see p. 92).
Spread . Underground rhizomes may be dispersed and
be the agents of spread when the weed is dug up.
Control . A cultural control involves regular cutting
down of the weed and maintaining good levels of soil
fertility (to allow the garden plant to compete). Sprays
of herbicides containing glyphosate may be successful
on bare ground, especially if the foliage is quite young

Liverworts

Liverworts (in the Hepatophyta division, fairly closely
related to the mosses, see p. 52) have several weed