Biology Reference
In-Depth Information
and one of the aims of a bioherbicidal formulation of
C. piaropi
should be as a syner-
gist that magnifies the effects of the arthropods and intensifies the biotic stress.
Attempts should be made to use mixtures of pathogens, as has been attempted by
Den Breeÿen (1999) and Jiménez and Balandra (2007), as well as strains of
C.
piaropi
with a higher level of aggressiveness, higher phytotoxin, and better fitness
than previously used (Tessmann et al. 2008).
10.4
Work in Progress: Bioherbicides for Cogongrass
and Tropical Soda Apple
10.4.1
Solanum viarum-Tobacco Mild Green Mosaic
Tobamovirus: Use of a Plant Virus
Tropical soda apple (
Solanum viarum
Dunal, TSA,
Solanaceae
) is an invasive weed
in Florida and several southeastern states in the USA where it is arguably the
number one invasive plant species in livestock pastures and surrounding natural
areas. Currently, more than a million acres of ranch and natural lands are estimated
to be infested with TSA. Native to Argentina, Brazil, and Paraguay, TSA is known
to occur in several countries in Central and South Americas and Africa, the
Caribbean, and the Indian subcontinent (Mullahey et al. 1998). It is designated a
noxious weed in the USA under the US statutes. It is a perennial shrub that has been
dubbed
the plant from hell
to aptly describe its thorny and harmful nature, invasive-
ness, a propensity to form impenetrable thickets, and the difficulty in controlling it
(Fig. 10.4). Aided by cattle, wildlife, and birds that eat TSA fruit and spread the
seed, TSA has the potential to spread throughout the continental USA (Patterson
1996).
TSA is highly susceptible to a plant virus,
Tobacco mild green mosaic tobamo-
virus
(TMGMV) and is killed from a hypersensitive reaction to the virus infection
(Charudattan et al. 2004; Charudattan and Hiebert 2007). TSA plants are killed
completely and quickly; plants of all ages from the seedling to the mature stages
are killed in about 21-42 days following inoculation. Younger plants are killed
sooner than older plants but the final level of weed kill is generally the same.
TMGMV is a member of the plant virus genus
Tobamovirus
and occurs naturally
in Florida and other regions of the USA and the world in about 25 different plant
species. It is worldwide in distribution on susceptible
Nicotiana
species (wild and
cultivated tobaccos) but is not known to cause any significant economic losses to
Fig. 10.4
Control of tropical soda apple by using the plant virus
Tobacco mild green mosaic
tobamovirus
(TMGMV).
To p
row:
Left
: TSA foliage is covered with thorns, making the plant
harmful and unpalatable to cattle.
Middle
top and
bottom
: TSA flowers and fruits that are green
when immature and yellow when mature.
Right
: Vertical (
top
) and horizontal cross sections of
fruits revealing abundant seeds. Second row from top: TSA infestation around trees (
left
) and in
