1	Banana Bunchy Top Disease (BBTD) Symptoms, Diagnosis and Management
2	Contents Symptom recognition Diagnosis (ELISA) How BBTD spreads History of BBTD in Hawaii The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
3	Banana Bunchy Top Disease The disease (BBTD) is caused by a plant pathogenic virus known as banana bunchy top virus (BBTV) No banana varieties are resistant to the disease BBTV is vectored by an insect, the banana aphid (Pentalonia nigronervosa) Infected bananas are safe to eat The disease eventually kills banana mats
4	Symptom recognition Symptom recognition Diagnosis (ELISA) How BBTD spreads History of BBTD in Hawaii The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
5	“Bunchy Top” Symptoms Youngest leaves are bunchy Leaf margins are yellow or brown Leaf margins are wavy Leaves are stiff, narrow and upright
6	“Bunchy Top” Symptoms: leaves are bunched, narrow, with yellowed fringes, are stiff, upright
7	“Bunchy Top” Symptoms: Compare Diseased vs. Healthy Plants Diseased plants have leaves that are bunched up, narrow, stiff, upright, and with yellow and irregular or wavy leaf margins.
8	“Morse code” Symptom on Leaves: “dots and dashes” along veins
9	“Morse code” Symptom on Leaves: Compare Diseased vs. Healthy Leaves Top: Healthy leaf (top) has no Morse code streaking along veins Bottom: Diseased leaf (bottom) shows the characteristic Morse code streaking associated with BBTD.
10	“Green J-hooks” on Leaves: Some leaf veins are dark green colored and form a “hook” shape as the mid rib is approached In these photographs, the green J-hooks are accompanied by the “Morse code” symptom
11	Petioles & Leaf Sheaths are Mottled, Streaked
12	Petioles & Leaf Sheaths are Mottled, Streaked compare diseased vs. healthy plants Top: Diseased plant with streaked petioles. The white, powdery layer of cells was rubbed off the petiole to reveal the symptom Bottom: healthy plant without petiole streaking or mottling
13	Male Flower is Streaked or Mottled compare diseased vs. healthy plants Top: Diseased plant with streaked and mottled male flower (“bell” flower) Bottom: Healthy plant without streaking or mottling of bell flower.
14	Fruits Deformed or Stunted Fruiting habit may be disrupted, fingers may be twisted, bunches small. Diseased plants may not even flower or fruit at all when infected at a young developmental stage.
15	BBTD symptom review Leaves are bunchy, narrow, stiff, and upright Leaves have yellow (sometimes brown) and wavy margins Plants are stunted Leaves have “Morse code” dots and dashes along veins Leaves have “green J-hooks” along veins near midrib Petioles and leaf sheaths are streaked or mottled Male flowers may be streaked or mottled Fruits may be stunted and deformed
16	Diagnosis of BBTD using ELISA Symptom recognition Diagnosis (ELISA) How BBTD spreads History of BBTD in Hawaii The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
17	Diagnosis of BBTD Using ELISA ELISA is a test based upon an antibody reaction to the BBTV virus particles in the banana plant sap (ELISA = Enzyme-linked Immunosorbent Assay) The ELISA test is a color change reaction to banana plant sap. Obtain from sections of suspect banana leaves as shown at right. Yellow indicates a positive reaction and that BBTV is present in the plant sap. The University of Hawaii Cooperative Extension Service can perform this test for a fee.
18	How BBTD spreads Symptom recognition Diagnosis (ELISA) How BBTD spreads History of BBTD in Hawaii The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
19	How Bunchy Top Spreads The most important way that banana bunchy top disease (BBTD) spreads in Hawaii is by humans moving diseased planting material between and among Hawaiian islands (according to the Hawaii Dept. of Agriculture). BBTD is also spread by a small insect, the banana aphid. The aphids pick up the virus while feeding on diseased plants. These aphids are infective; some can fly and spread the disease to healthy plants. The only known host for the banana bunchy top virus (known as BBTV) is banana.
20	History of BBTD in Hawaii Symptom recognition Diagnosis (ELISA) History of BBTD in Hawaii How BBTD spreads The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
21	History of BBTD in Hawaii tracking the epidemic Oahu 1989-July Punaluu Movement Hawaii 1995-Oct. North Kona 4 yrs. Kauai 1997-Sept. Kilauea Town 2 yrs. Kauai 2000-Apr. Kapahi 3 yrs. Kauai 2000-Apr. Kilauea Town 3 yrs. Maui 2002-Dec. Pukalani 2 yrs. Hawaii 2004-Apr. Keaau, North Kohala 1.3 yrs.
22	BBTD Distribution in Hawaii red dots indicate the known distribution
23	The role of the banana aphid Symptom recognition Diagnosis (ELISA) How BBTD spreads History of BBTD in Hawaii The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
24	The Banana aphid (Pentalonia nigronervosa) Top: Adult, wingless banana aphid on a leaf surface (very highly magnified). Bottom: Colony of banana aphids feeding on a young banana plant (highly magnified).
25	The Banana aphid (Pentalonia nigronervosa) Top: Banana aphids often feed on tender tissues in protected areas of the plant, such as under leaf sheaths near the pseudostem (here the leaf pulled back and away from the plant). Bottom: Banana aphids range in color from brown to black. Here a colony of banana aphids was found feeding in the protected area where the leaves fold around the pseudostem.
26	The Banana aphid (Pentalonia nigronervosa) Top: Banana aphids often gather on the youngest leaves of young plants. They may form large colonies where they are uncontrolled and protected by ants. They feed by piercing the plant cells with a syringe-like mouthpart. Bottom: Banana aphids have a wide host range, including noni. Here a colony of banana aphids on noni is tended by long-legged ants. The ants feed on the liquid honeydew excreted by the aphids, manage the aphid colony, and protect the aphid colony from enemies.
27	Aphid control tips Symptom recognition Diagnosis (ELISA) History of BBTD in Hawaii How BBTD spreads The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
28	Aphid control tips Inspect bananas regularly and other hosts for colonies of the banana aphids Use sprays of approved insecticides if desired to control aphids Control ants Destroy aphids on diseased plants immediately Control weeds Invite beneficials Prune mats of unwanted suckers Control weeds Diversify the farm
29	How to properly destroy BBTD-diseased plants Symptom recognition Diagnosis (ELISA) History of BBTD in Hawaii How BBTD spreads The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
30	Elimination of diseased plants Plants with BBTD and their entire mats should be destroyed promptly. As long as they are alive, they are a potential source of disease for other plants. Plants and mats can be destroyed manually by digging out the corms, or by injecting an approved herbicide such as Roundup Ultra Max^Ò.
31	Elimination of diseased plants Proper elimination of plants with bunchy top is a two-step process: Step 1: Kill aphids first … they may spread the virus before the plant dies (use approved insecticides such as insecticidal soap for residential growers, and other registered banana pesticides for commercial farmers, such as diazinon or imidacloprid). Step 2: Kill banana plants (use approved herbicide).
32	Herbicide injection to destroy plants with BBTD Top: Using a screwdriver, safety clothing, and a bottle of pure strength herbicide, plants are injected (please see Roundup Ultra Max^Ò label for directions). Bottom: 6 weeks after injection, plants are almost dead.
33	Integrated Management of BBTD Symptom recognition Diagnosis (ELISA) History of BBTD in Hawaii How BBTD spreads The role of the banana aphid Aphid control tips How to destroy BBTD-diseased plants Integrated management of BBTD
34	Integrated management of BBTD Avoid moving banana plants around the islands Plant disease-free material only Long-term aphid control Regular inspection of plants for symptoms Destroy diseased plants properly Create banana-free buffer zones Report new outbreaks to the HDOA Work together as a community Support research and development for long-term solutions
35	More BBTD information within this web site FAQ and internet links Aphid control tips BBTD history, press releases for Hawaii BBTD integrated pest management Herbicide injection for diseased plants Free publications
36	Credits The University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources, Cooperative Extension Service The Hawaii Department of Agriculture