Banana bunchy top virus (BBTV) is one of the most serious diseases of banana. It is difficult to eradicate once established. BBTV symptoms initially appear as dark green streaks in the veins of banana leaves. Later, leaves emerge narrower than normal with yellow margins and are stiff, erect, and bunched at the top of the plant. The virus spreads through propagation materials and by the banana aphid acquiring the virus after feeding on infected plants. Severely infected plants often do not fruit, and fruit that does form is distorted and twisted. Control measures include using virus-free materials, removing infected plants, and insecticidal soaps, though insecticides have little effect on virus spread.

1. BANANA BUNCHY TOP DISEASE (Mandeep Poudel)

2. Banana bunchy top virus (BBTV) is one of the most serious
diseases of banana. Once established, it is extremely difficult
to eradicate or manage.
Family: Circoviridae
(from being circular,
round)
Genus: Nanovirus (from
being small, nanos =
dwarf)

3. Symptoms
Initially BBTV consist of dark
green streaks in the veins of
lower portions of the leaf
midrib and the leaf stem
(petiole). The streaks also
occur, but are less
prominent, in the veins of the
leaf blade (lamina). This
symptom is some- times
referred to as “Morse code
streaking” because the
streaks are irregular and
resemble a series of “dots”
and “dashes.”

4. :
The hook-like extensions
of the leaf lamina veins
can be seen in the
narrow, light-green zone
between the midrib and
the lamina, hooks point
down along the midrib
toward the petiole. They
can best be seen by
back-lighting the leaf
against the sky.

5. Symptoms
They appear to be “bunched” at
the top of the plant, the
symptom for which this disease
is named.
The new leaves emerge with
difficulty, are narrower than
normal, are wavy rather than
flat, and have yellow (chlorotic)
leaf margins.leaves are stiff and
erect, are shorter and narrower
than normal leaves.

6. Disease spread and development
Propagative materials such as
rhizomes, suckers, or tissue-
cultured meristems and over
short distances by the banana
aphid Pentalonia nigronervosa.
Banana aphid acquires the
virus after at least four (but
usually about 18) hours of
feeding on an infected plant.
Remains for a period of 15–20
days, i.e. through its adult life.

7. Nature of Damage:
Disease symptoms usually appear about a month after
infection.
The aphids are most likely to be hiding or feeding. This
includes the leaf petioles and the “pockets” where the petioles
separate from the pseudostem.
The inflorescence and fruit bunch either fail to form or fail to
emerge from the banana pseudostem.
Severely infected banana plants usually will not fruit, but if fruit
is produced, the banana hands and fingers are likely to be
distorted and twisted

8. Control Measures:
Minimise virus infection: Quarantine measures, the use of
virus-free propagating material, locating new plantations
away from older infected ones, and destroying all
volunteer banana plants.
Reduction in spread: Roguing of infected and
nearby plants seems to reduce the rate of virus spread.
Spraying with Insecticidal soaps.
Attempts to control the aphid vector with insecticides
have little effect on the spread of this virus.