Agriculture Reference
In-Depth Information
Box 5.4 Common Nematode Pests of Grapevines
The most widely distributed nematode pest is the root knot nematode (genus
Meloidogyne ), which is found in most sandy soils in Australia, especially in the
Sunraysia and Riverland regions. At least four species— M. javanica, M. incognito,
M. arenaria , and M. hapla —are serious pests of grapevines in different parts of the
world. The nematode invades a root, causing cells to swell and form a gall about
3 mm in diameter in which the females breed and lay eggs. A single gall with a
succession of females may survive for several years. Some cover crops act as alternate
hosts for these nematodes. Figure B5.4.1 shows galls on a vine root system severely
infected with M. javanica , the most serious nematode pest in Australia.
Figure B5.4.1 Grapevine
roots showing galls associated
with Meloidogyne javanica
infestation. (Photo courtesy
of Dr. Loothfar Rahman,
National Wine and Grape
Industry Centre, Wagga
Wagga, New South Wales,
Australia.)
The most common species of root lesion nematode (genus Pratylenchus )
found in vineyards are P. zeae and P. vulnus ; the latter is the more serious pest
in the United States. Like Meloidogyne , these nematodes also live inside the
roots. Although they burrow through the tissues without producing galls,
these nematodes do cause root lesions that predispose to the invasion of fungal
pathogens such as Cylindrocarpon, Phaeomoniella , and Phytophthora .
he dagger nematode (genus Xiphinema ) is larger than other nematodes
and feeds outside the roots, causing swelling of the root tips. The most common
species in vineyards worldwide is X. index , the main vector of grape fanleaf virus.
However, strains of X. americana are probably more widespread in Australian
vineyards.
The citrus nematode ( Tylenchulus semipenetrans ) also feeds outside the roots.
It is restricted to a few plant genera—most importantly, citrus and grapevines—
and so is common where these two crops are grown in proximity.
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