Biology Reference
In-Depth Information
prohibit their long-term use for parthenium management in grazing areas, public
and uncultivated areas and forests.
12.4.2 Physical/MechanicalControl
Manual removal of parthenium before flowering is often carried out to reduce local-
ised infestations in residential areas and high-value crops, but not in large infesta-
tions. However, handling of parthenium is not recommended because of the health
risks associated with parthenium weed. Other physical methods such as grading,
slashing and ploughing in large infestations can provide some relief over short
term, but they are not effective in the long-term management, as they are known to
enhance regeneration of parthenium (Kohli et al. 1997). It has been suggested that
ploughing in parthenium in the rosette stage before seed-set helps to retain soil
moisture, but this practice needs to be followed up by sowing a crop or direct seed-
ing of perennial pasture.
12.4.3 CompetitiveDisplacement
Parthenium is known to be allelopathic, and is capable of reducing growth and ger-
mination of crops resulting in reduced crop yield and contaminated crop products.
Several beneficial plants are also known to be allelopathic and have the potential to
compete and displace parthenium (Table 12.1). Most of the research so far on using
beneficial plants to competitively displace parthenium has been restricted to India
(Akula and Kondap 1997; Dhawan et al. 1997; Joshi 1991a, b; Kandasmy and
Sankaran 1997; Kauraw et al. 1997; Sushilkumar and Bhan 1997; Yaduraju et al.
2005; Gautam et al. 2005a), with only limited studies done in Australia (O'Donnell
and Adkins 2005), South Africa (van der Laan 2006) and Pakistan (Anjum and
Bajwa 2005; Anjum et al. 2006; Javaid et al. 2005). Potential for the large-scale use
of competitive plants to displace parthenium in the field is yet to be studied.
12.4.4 Fire
Fire is commonly used for pasture management and woody weed control in north-
ern Australia (Grice and Brown 1996). Parthenium-dominant pastures will not
carry a fire, because of lack of adequate fuel load for an effective fire to occur. In
areas with adequate fuel load (i.e. national parks, road side infestation, etc.), more
parthenium incidence was observed in burnt areas compared with nearby unburnt
areas. On the basis of anecdotal evidence, burning of parthenium-infested areas is
