The document discusses various biological and mechanical methods for controlling weeds and nematodes. It describes how the head smut fungus Sporisorium ophiuri provides biological control of Rottboellia cochinchinensis by infecting seedlings. Mechanical control of R. cochinchinensis involves burning, tilling, and leaving fields fallow. Several Aphtona flea beetle species provide biological control of leafy spurge by feeding on roots and foliage. Tagetes erecta releases chemicals from its roots that are toxic to root-knot nematodes in the genus Meloidogyne. Higher organic matter and good soil care can also help minimize nematode damage.

1. Biological&Mechanical
Control
Weeds and Nematodes
Tyrone M. Villanueva BSA 3-1 AnSc

2. Plants became weeds
when natural enemies
are ineffecive

3. Rottboellia cochinchinensis &
Sporisorium ophiuri

4. Rottboellia cochinchinensis &
Sporisorium ophiuri (Biological)
"Studies have also been conducted that aim to develop
classical biological control for R. cochinchinensis using the
head smut (Sporisorium ophiuri) (Ellison and Evans 1995 ),
whose release has been recently approved in Costa Rica.
Head smut is extremely host specific (Valverde et al. 1999 ).
It is soilborne and infects R. cochinchinensis seedlings as
they emerge, thereby causing a systemic infection that leads
to seed sterility.

5. Rottboellia cochinchinensis &
Sporisorium ophiuri (Mechanical)
According to NAPPO (2003) "R. cochinchinensis in East
Africa is controlled by a combination of cultivation followed
by fallowing for at least 2 years. The infested site is first
burned to destroy the seeds on the surface. Next, it is
ploughed to stimulate germination of seeds in the top soil
horizon. Following this, deep ploughing is done to bury the
seedlings. After this, the land is left fallow until the buried
seeds expire and the land is considered clean (Holm et al.
1997)."

6. Leafy Spurge & Aphtona spp.

7. Leafy Spurge & Aphtona spp. (Biological)
 stem/root boring beetle
 Flea beetle (Aphtona spp.)
-A. flava
-A. lacertosa
-A. abdominalis
-A. nigriscutis

8. Leafy Spurge & Aphtona spp. (Biological)
 Reducing leafy spurge density
 Adult flea beetle feed on foliage
 Larva feed on root major damage on plant
 Small larvae feed on fine root hairs lead to reducing water
and nutrients absorption.
 Larger larvae feed on root crown, destroying root tissue
directly/indirectly making plant more susceptible to
herbicides and soil borne pathogen

9. Purple loosestrife (Biological)
 Reduced spurge infestation
 Do not always provide predictable and consistent levels of
control
 May take several years
 Not “quick fix”
 Practice patience to ensure long term benefits

10. Nanophyes marmoratus

11. Purple loosestrife (Biological)
 Black-margined loosestrife beetle (Galerucella
calmariensis)
 Golden loosestrife beetle (Galerucella pusilla)
 Root-boring weevil (Hylobius transversovittatus)
 Flower-feeding weevil (Nanophyes marmoratus)

12. Meloidogyne & Tagetes erecta

13. Meloidogyne & Tagetes erecta
(Biological)
Root knot nematode (Meloidogyne spp.) can be
effectively managed in home gardens without pesticides.
One relative to using nematodes is to intercrop and rotate
vegetables with marigolds. Most cultivars of African marigold
(Tagetes erecta) and French marigold (T. patula) are
effective in reducing the most common root-knot nematode
populations—Meloidogyne incognita and M. javanica. The
roots of these attractive flowering plants contain chemicals
that kill nematodes.

14. Meloidogyne & Tagetes erecta
(Biological)
Soil amendments containing chitin, made from
shells of crustaceans, have been shown to be
effective at reducing nematode populations. It
serves as a food source for chitin eating fungi and
the shells of nematode eggs are also made of chitin
so the fungi attacks them as well.

15. Meloidogyne & Tagetes erecta
(Mechanical and Physical)
Allelopathy is the ability of an organism to produce chemicals that
are toxic to other organisms. Marigold roots release the chemical alpha-
terthienyl, one of the most toxic naturally occurring compounds found to
date (Gommers and Bakker, 1988). This compound is nematicidal,
insecticidal, antiviral, and cytotoxic (Arnason et al., 1989; Marles et al.,
1992).The presence of alpha-terthienyl inhibits the hatching of nematode
eggs (Siddiqui and Alam, 1988).
 Meloidogyne spp. juveniles were unable to fully develop in the roots
of T. erecta (Ploeg and Maris, 1999).

16. Meloidogyne & Tagetes erecta
(Mechanical)
Higher organic matter content may also stimulate the
activity of pests and parasites of root-feeding nematodes,
which may reduce their populations in the soil. Good
irrigation, fertilization, and soil care will help minimize
damage caused by nematodes.

17. Reference:
 http://www.issg.org/database/species/reference_files/ro
tcoc/rotcoc.pdf
 http://edis.ifas.ufl.edu/ng045
 http://www.toxipedia.org/display/ipmopedia/Root-
Knot+Nematodes