PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
BIOLOGY AND IDENTIFICATION
Nematode diseases
NO. DISEASES
IN AUSTRALIA
Nematodes occur in soil, plants, animals and humans. More than 300 species are
known to be parasitic on plants and it is considered there may be up to 1 million
species worldwide. Nematode populations are related to soil properties and so
are useful indicators of soil conditions (Hodda et al 1999). Nematode plant
pests cost about 10 per cent of world food production (Hodda 2008).
Nematoda www.ento.csiro.au/science/nematode.html
CBIT Nemasys www.cbit.uq.edu.au/software/nemasys/
Biological Crop Protection www.biolcrop.com.au/
Australasian Association of Nematologists nematologists.org.au/
SOME
DISTINCTIVE
FEATURES
Do not confuse
nematodes with
earthworms
or some fly larvae, eg
fungus gnats, both of
which are larger
BODY
MOVEMENT
1. Many celled animals with a true digestive cavity.
2. Mainly microscopic (x 10), some visible to the naked eye.
3. Generally 0.5 - 3.0 mm long, a few species are longer.
4. Generally ‘eel-like’, adult females of some species are
spherical or pear-shaped. More or less transparent.
5. Body is unsegmented with no legs or other appendages.
They move by means of special muscles in water films
between and around soil particles.
Do not confuse nematodes (Phylum Nematoda) with earthworms (Phylum
Annelida) or some fly larvae, eg fungus gnats, both of which are larger.
LIFE CYCLE
Root knot
nematode
Life cycles of most plant parasitic nematodes are similar, eg eggs,
juveniles (which look like adults) and adults (males and females). The sexes
are usually separate, however, males may be missing. Also females may
reproduce parthenogenically. At optimum temperature and moisture a life
cycle may take from 2-4 weeks.
Many variations,
eg foliar nematodes,
stem and bulb
nematodes
252 Nematode diseases