Published Date: 2006-12-09 00:00:00
Subject: PRO/PL> Bunchy top, banana ï¿½ Australia (NSW): Reintroduction
Archive Number: 20061209.3474
BUNCHY TOP, BANANA � AUSTRALIA (NEW SOUTH WALES): REINTRODUCTION
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: 5 Dec 2006
From: ProMED-mail <firstname.lastname@example.org>
Source: The Australian [edited]
The bunchy top banana disease has been discovered
in Richmond Valley, north of Lismore, the most
southerly the disease has been found.
NSW Primary Industries Ian Macdonald said today
the disease had been discovered on a commercial banana plantation.
Mr Macdonald said the Department of Primary
Industries (DPI) would destroy all plants within
20m of the infected plants and inspect nearby
properties over the next couple of weeks.
"This is the most southerly outbreak of bunchy
top for decades and poses a threat to banana
plantations in the Richmond valley, which has
been free of bunchy top since the 1970s," he
said. "Plants affected by bunchy top typically
have shorter, narrower, bunched-up leaves that
are often a bit yellow and turned up at the edges," he said.
Bunchy top is spread by plant-sucking insects and by planting material.
[The crop plant banana, _Musa x paradisiaca_,
develops symptoms of the disease bunchy top when
infected by banana bunchy top virus (BBTV,
family: _Nanoviridae_; genus: _Babuvirus_).
BBTV causes irregular streaking in the veins and
lower portion of the leaf. The streaking
resembles dots and dashes, sometimes referred to
as 'Morse code streaking'. New leaves on mature
plants infected with BBTV have difficulty
emerging. These new leaves are narrower than
normal, wavy rather than flat, and have yellow
leaf margins. They appear to be 'bunched' at the
top of the plant, resulting in the name of this
virus. Severely infected plants do not usually
produce fruit or, if they do, the banana hands
and fingers are usually distorted and twisted.
BBTV was first reported in banana (_Musa_ spp.)
in Fiji in 1879. It has subsequently spread
throughout the South Pacific, Asia, and Africa,
and Australia. It has not appeared in Central or
South America. BBTV is vectored by the banana
aphid (_Pentalonia nigronervosa_). Disease
management is predicated on integrated pest
management (IPM). Strategies include long-term
aphid control (killing of weed hosts for aphid
control, use of predators and parasites, control
of aphids on alternate hosts), frequent scouting
for diseased plants, destruction of diseased
trees, and replanting with certified virus-free
material. All of these practices are used in
NSW, Australia in a relatively successful
suppression program, but like all vectored plant
viruses, it is very difficult to achieve full
eradication of the pathogen. This new report in
the Richmond Valley where the virus has been
absent since the 1970�s, represents a southward
extension of the virus range, and will no doubt
lead to an increase in suppression activity.