Agriculture Reference
In-Depth Information
Fig 15.21 Passionfruit woodiness disease. Cut fruit showing smaller
cavity.
Cucumber mosaic virus
alone, or in combination with the
previous viruses, can also cause woodiness.
Fig 15.22 Crinkled leaf symptoms of woodiness disease.
Symptoms
Leaves: a light and dark green mosaic pattern develops,
often with a light yellow speckle. Leaves may be puckered
and crinkled.
Fruit: severely affected fruit is small and deformed with an
abnormal, thick, hard rind and a small pulp cavity.
Symptoms are generally much more severe in cool weather
conditions. Both the purple passionfruit (
Passif lora edulis
f. sp.
edulis
) and
P. edulis
f. sp.
flavicarpa
are susceptible
and may show severe symptoms.
The 'common strain' probably comprises a range of
isolates and viruses that produce severe woodiness
symptoms on the purple passionfruit but are tolerated
by hybrids (
P. edulis
f.
edulis
×
P. edulis
f.
flavicarpa
). In
these hybrids, a range of mild-to-severe foliage mosaic
symptoms develop but few (and woody) fruit develop.
Mild strains of
passionfruit woodiness virus
, which had
less effect on both purple passionfruit and hybrids, have
been selected in the past. These have been used to cross-
protect vines against infection with more severe strains.
However, these strains no longer appear effective,
possibly due to the complex of viruses now associated
with the disease.
Source of infection and spread
The viruses are transmitted from infected to healthy
vines by aphids with only very short feeding periods
required for transmission. Aphids rarely colonise
passionfruit, and transitory aphids passing through the
crop are responsible for almost all transmission.
Woodiness virus
(
-es
) may also be spread in infected scion
wood and rootstocks, and on pruning implements. Most
cultivated and wild species of
Passif lora
are hosts. Once
infected, vines cannot be cured.
The viruses are not transmitted through seed.
The 'tip blight' strain of
passionfruit woodiness virus
is
harboured by the wild corky passion vine (
P. suberosa
)
and causes necrotic terminal blighting of
P. edulis
f. sp.
edulis
.
A virus strain or mixture causing severe leaf mosaic and
woody fruit, even in hybrids that normally tolerate the
virus, occurs in parts of south Queensland. It often causes
a necrotic speckle on older leaves.
Management
•
Importance
Woodiness is a major disease in Queensland and several
strains of the virus(-es) occur.
Severe strains and virus mixtures can be contained by
careful selection of propagation material from areas
where they are not common.
