Biology Reference
In-Depth Information
Chapter 10
Biological Control of Invasive Weeds in Forests
and Natural Areas by Using Microbial Agents
Alana Den Breeÿen and Raghavan Charudattan
Abstract
Biological control of forest weeds by using microbial plant pathogens
has been tried in a few cases with some notable success. Diverse weed targets
such as broad-leaved exotic invasive tree species, native tree and shrub species that
recolonize following clearcutting, and invasive shrubs, annual and perennial herbs,
and vines have been targeted. Examples of several programs, some highly success-
ful and others with outcomes still uncertain, are described including the control of
Acacia saligna
by the introduced rust fungus
Uromycladium tepperianum
in South
Africa, broad-leaved tree species by
Chondrostereum purpureum
in the Netherlands
and Canada,
Clidemia hirta
in Hawaii by
Colletotrichum gloeosporioides
f.sp.
clidemiae,
Ageratina riparia
by the foliar smut fungus
Entyloma ageratinae
in
Hawaii and New Zealand,
Hedychium gardnerianum
by the bacterium
Ralstonia
solanacearum
in Hawaii,
Passiflora tarminiana
by
Septoria passiflorae
in Hawaii,
Imperata cylindrica,
an exotic invasive grass in the southeastern USA, by
Bipolaris
sacchari
and
Drechslera gigantea,
Eichhornia crassipes
by fungal pathogens in
integration with arthropods, and
Solanum viarum
by
Tobacco mild green mosaic
tobamovirus
(TMGMV). This list of examples is not complete but it is meant to
illustrate the classical vs. bioherbicide strategies, integrated control using patho-
gens and insects, and different types of pathogens (biotrophic vs. necrotrophic
fungi, a bacterium, and a virus). Pathogens that are easily disseminated from ini-
tial release sites through rapid buildup of secondary disease cycles have produced
some of the highly successful programs compared with pathogens that require
postrelease augmentation in the form of multiple releases, inundative applications,
or technological aids.
Keywords
Bioherbicide
Classical biocontrol
Forest weeds
Weeds in natural
areas
Plant pathogens
A.D. Breeÿen and R. Charudattan(
)
Plant Pathology Department, University of Florida, Gainesville, FL 32611-0680, USA
rcharu@ufl.edu
