Environmental Engineering Reference
In-Depth Information
Fig. 9.4
The goal of weed or invasive plant control is usually reduction of
impact to an economically acceptable level in agroecosystems or an ecologically
acceptable level in wildland ecosystems.
Arundo donax
(giant reed) is illustrative
of a highly invasive plant that displaces most of native riparian vegetation. This
weed dries in winter, breaks off and washes downstream in fl oods, burns readily,
creating a considerable hazard. A few years ago a huge mat of giant reed washed
downstream and took out Van Buren Bridge in Riverside, California, USA, costing
the city US$5 million to replace it with this one. Photo: Michael Rauterkus.
Physical methods of control include any technique that uproots, cuts, buries,
smothers, or burns vegetation. Depending on the habitat and any restrictions per-
taining to it, these methods can employ manual or machine power. In general,
many more techniques of physical control can be used in agroecosystems where the
soil is bare prior to crop planting than in wildlands where native vegetation might
be present. Physical methods that are suitable for use in wildland ecosystems con-
sist of hand pulling or using manual cutting or hoeing implements; using fi re in the
form of controlled burning; using machines for mowing, shredding, chaining, or
dredging; and in some cases, using mulches or solarization (Ross and Lembi 1999;
Wittenberg and Cock 2005; Radosevich
et al
. 2007).
9.4.2.1 Hand pulling and using manual implements
Hand pulling and hoeing are the oldest and most primitive forms of weed con-
trol, and in general, have fewer negative impacts on the environment than other
