BANANA BUNCHY TOP K R.pptx

BANANA BUNCHY TOP K R.pptx

1. BANANA BUNCHY TOP. (definition,etiology,symptomatology and control) K R MICRO NOTES 1

2. Banana bunchy top is a serious plant viral disease caused to banana plant. The virus that causes the disease is called has banana bunchy top virus(BBTV). First identified in Fiji in 1879. it was named after the symptoms, where the infected plants are stunted and have “ bunchy” leaves at the top. Hence the name banana bunchy top. K R MICRO NOTES 2

3. It is caused by Banana bunchy top virus. Family: Nanoviridae Genus: Babuvirus Species : Banana bunchy top virus Etiology BBTV is the sole member of the genus Babuvirus in the family Nanoviridae.  The genome of BBTV is made up of at least six circular, single-stranded DNA components, each about 1 kilo-base pair in length. Replication takes place by rolling circle replication, a unidirectional nucleic acid replication that can result in rapid synthesis of single-strands of DNA. Viruses in the genus Babuvirus are non-enveloped, with icosahedral and round geometries, and T=1 symmetry . The diameter is around 18-19 nm . Genomes are multipartite with 6 to 8 circular segments. Genome size is around 81 kb . K R MICRO NOTES 3

4. Small reddish-brown to almost black oval shaped aphids. Aphids have two characteristic projections from the rear of the abdomen. Colonies of adult and immature stages are found on the pseudo stem (of banana plants) under the leaf bracts and between the bunch bracts and the branch stalk . Colonies can also be found in the unfurled top leaves of young plants and suckers or under leaf bases near ground level . Winged forms have prominent forewings with dark pigmented veins Domain: Eukaryota  Kingdom: Metazoa  Phylum: Arthropoda  Class: Insect  Order: Hemiptera  Family: Aphididae  Genus: Pentalonia  Species: Pentalonia nigronervosa causative agent. classification K R MICRO NOTES 4

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6. Banana aphids can spread banana bunchy top by feeding on infected banana plants. The aphids then transmit the virus by feeding on healthy banana plants. Once infected, the virus spreads throughout the whole plant. Infected banana plants do not show bunchy top symptoms until 2 or more new leaves have been produced after being infected by the banana aphids . This takes between about 19 days in summer to about 125 days in winter. Once bunchy top symptoms are visible , the newly infected plant becomes a source of the virus for further spread. Banana aphids can acquire the virus after at least 4 (but usually about 18) hours of feeding on an infected plant. Aphids can retain the virus through their adult life, a period of 15–20 days . Banana aphids can then transfer the virus to susceptible healthy plants as they feed. Spread of infection. K R MICRO NOTES 6

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8. Insecticides are chemicals that are designed to kill insects by destroying various parts of the nervous system. To control aphid, use one of the following insecticides: Imidacloprid at 125gm / 120 litres of water Acetamiprid 125gm / 120 litres of water Repeat the spray on the crop with a minimum interval of one week Visit the field twice a week to survey the intensity of the disease and insect Banana bunchy top disease can be effectively controlled by the eradication of diseased plants. Maintain clean , weed free field for early detection of infested suckers. Control measures. K R MICRO NOTES 8

9. AGRICULTURAL MICROBIOLOGY-G.RANGASWAMI, D.J BAGYARAJ COLLEGE MICRIBIOLOGY-S.SUNDARA RAJAN. REFERENCES. https://en.wikipedia.org/wiki/Banana_bunchy_top_virus https://cms.ctahr.hawaii.edu/wangkh/Research-and-Extension/Banana-IPM/Guidebook/CHPT2-BBTV https://www.slideshare.net/BooapthiN/banana-bunchy-top-disease-140677161 https://www.cabi.org/isc/datasheet/8161 K R MICRO NOTES 9