Biology Reference
In-Depth Information
crops. Through extensive research, our group has established that TMGMV could
be used safely and effectively as a bioherbicide for TSA (Charudattan and Hiebert
2007; Charudattan et al. 2004). When properly used, TMGMV can provide nearly
100% TSA control, but repeated applications may be necessary to treat plants that
emerge after the initial treatment and plants that are missed in the first treatment.
TMGMV could be easily multiplied in the tobacco (
Nicotiana tabacum
) variety
“Samsun”
nn
, in which it elicits a mild, nonlethal, systemic mosaic disease and
accumulates to a high titer of around 1-2 mg/g of fresh leaf tissue. Taking advan-
tage of this tolerant host-virus interaction, we have developed an industrial process
to mass-produce TMGMV and formulate it into two commercial formulations,
SolviNix
LC and
SolviNix
WP.
SolviNix
(
Solvi
from
Solanum viarum
and
Nix
from
put a stop to
) is undergoing large-scale precommercial field testing under an US
EPA-issued Experimental Use Permit (EUP). In these trials,
SolviNix
is applied as
a postemergent aqueous spray using a boom sprayer that is modified to abrade and
spray simultaneously or with a high-pressure sprayer. The former is used for large,
open areas while the latter is used for spot applications in wooded areas, under
trees, and other areas inaccessible to the spray boom.
We have addressed the risks to nontarget plants, animals, and the environment
through a comprehensive risk-analysis study (Charudattan et al., unpublished
report; Charudattan and Hiebert 2007). Being a plant virus, TMGMV does not pose
risks to any life form besides a small number of plants. Through an exhaustive host-
range study involving more than 400 plant species in 58 plant families, we have
confirmed that TMGMV is a pathogen adapted to plants in the
Solanaceae
.
However, the lethal hypersensitive reaction, as seen in TSA, is restricted to species
and cultivars of three genera:
Capsicum
(pepper),
Nicotiana
(tobacco), and
Physalis
(tomatillo). A mechanically transmitted virus that is not insect- or nematode trans-
mitted, TMGMV could be used safely without endangering nontarget plants. It is
anticipated that
SolviNix
will be registered in 2009 as the world's first virus-based
bioherbicide.
10.5
Imperata cylindrica
(Cogongrass) - Combined
Classical and Bioherbicide Strategies Using
Fungal Pathogens
Cogongrass (
Imperata cylindrica
, (L.) P. Beauv., Poaceae), ranked as one of the
world's top ten invasive weeds (Holm et al. 1977), infests over 500 million ha
worldwide including 200 million ha in Asia and an estimated 100,000 ha in south
eastern USA (Schmitz and Brown 1994). A warm-season, rhizomatous, perennial
grass species, cogongrass is found throughout tropical and subtropical regions of
the world (Holm et al. 1977). It is a serious weed in natural forests and pine planta-
tions in the Southeastern USA (Ramsey et al. 2003). It employs several survival
strategies that include having an extensive rhizome system, adaptation to poor soils,
