What is Banana Bunchy Top?
Banana Bunchy Top is a virus that stunts and deforms banana trees (BBTV). In the rare cases where an infected tree produces fruit, the bunch is small and misshapen. The virus is spread from plant to plant by banana aphids. Aphids will feed on an infected tree and carry the virus in their body, spreading it amongst healthy trees as they feed. Unfortunately, there is no cure for BBTV; once a tree is infected, it must be destroyed.
Banana Bunchy Top Virus was first identified on Oahu in 1989. Before long, it was found in Kona in the 1990s and is still continuing to spread across the Big Island to Hilo and North Kohala. It is also found on Kauai, Maui, and Molokai.
As BBTV spreads it can cause a significant threat to Hawaii’s banana industry. Backyard plants and wild bananas are also affected, and can be hosts of the virus that make it difficult for banana farms to keep their property free of BBTV and thus decrease banana production in the state.
Signs of Banana Bunchy Top Virus
- New leaves are narrow with yellow margins and appear ‘bunched’ at the top
- Leaves have dark green streaks and ‘J’ shaped hooks along the midrib of the leaf.
- Petiole (where the leaf meets the stem) are crinkled and molted.
- Small deformed fruits or no fruit at all
Treating Banana Bunchy Top Virus
When treating for BBTV it is very important to kill both infected plants and the aphids that transmit the virus. Aphids can be treated with most contact insecticides. Make sure to soak the plant thoroughly so that the insecticide gets underneath the petiole where aphids like to hide. May take a 2nd treatment to make sure all aphids have been killed. You can find an evaluation of various insecticidal soap applications here. Once infected with BBTV the tree must be killed, either through mechanical or chemical measures.
Mechanical: Cut the tree down completely and pull up any suckers. Be sure to return to the site often to remove any regrowth, as it has been shown that the entire banana mat becomes infested when a tree has BBTV. Do not move the dead trees, let them decompose in place.
Chemical: For chemical treatments use 1 ml of Roundup Ultra Max per 2-3 inches of tree diameter. The entire mat (bunch of trees) has to be treated. Symptoms can take days to show, so even if there only seems to be one infected plant in the bunch there is a high chance that the whole bunch is infected. All bananas within a 4 foot radius of the infected mat must also be treated.
- Remove any fruit.
- Treat for aphids.
- Use a screwdriver to create a downward sloping hole at a 45 degree angle about 1 foot above the ground. Small trees can have the herbicide injected at the top.
- Using a spray bottle apply the correct dose of herbicide.
- Repeat steps 3-4 for each tree in the mat. Do not use more than 15 ml per mat.
- Treat for aphids again if you still see them a few days after applying the herbicide.
- Wait six weeks for the tree to die before removing or destroying.
To manage BBTV, infected trees should be treated right away – so keep a close eye on your banana plants! Managing the vector (aphids) will greatly reduce the chance of BBTV. Aphids feed on many plants so it will help to treat any surrounding plants (even if they aren’t bananas) with an insecticide to reduce the aphid population. For more information on controlling BBTV and removing infected plants, visit the resources below.
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