Agriculture Reference
In-Depth Information
Figure 17.19
Yarrow plant showing stolons at the
base of the stem
17
Damage and location
. This strongly scented perennial,
with its spreading flowering head (Figure 17.19), is
a common hedgerow plant found on most soils at
altitudes up to 1,200 m. Its persistence, together with
its resistance to herbicides and drought in grassland,
makes it a serious turf weed.
Life cycle
. The seedling leaves are hairy and elongated
with sharp teeth (Figure 17.5). The mature plant
has dissected pinnate leaves (see p. 89) produced
throughout the year on wiry, woolly stems, which
commonly reach 45 cm in height, and which from May
to September produce flat-topped white to pink flower
heads. Each plant may produce 3,000 small, flat seeds
annually. The seeds germinate on arrival at the soil
surface.
Spread
. Seeds are dispersed by birds. When not
in flower, this species produces below-ground and
above-ground
stolons
(see Figure 17.19) which can
grow up to 20 cm long per year. In autumn, rooting
from the nodes occurs and new stems appear.
Control
. Control of this weed may prove difficult.
Routine scarification of turf does not easily remove the
roots. Gardeners may use products containing
2,4-D
and
mecoprop
against this weed.
Figure 17.18
Creeping thistle plant showing lateral
roots
Control
.
The seedling of this weed is not normally
targeted, although an attentive gardener may use a
hoe against this easily identified stage. Cutting down
plants at the flower bud stage when sugars are being
transferred from the roots upwards is a
cultural
control measure that helps weaken the plants. The
main cultural control, however, is the removal of main
roots and lateral roots by deep digging.
Gardeners are able to use herbicide products
which contain a mixture of
dicamba
,
MCPA
and
mecoprop-P
(all of these are translocated down to
the roots) on turf.
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 growing crops. Great care is needed to avoid
spraying foliage of garden plants.
Yarrow (
Achillea millifolium
)
This belongs to the plant family Asteraceae
(Compositae).
