Banana bunchy top virus

[Clayjacks]

Okay, who else has BBTV? Had to destroy an entire mat again, after planting in a new area with supposedly clean plants, and meticulously scouting for aphid vectors.
Just seeking knowledge from experience.

[rainyjim]

Clayjacks, I work in a plant virology lab at UH. If you have any specific questions I will do my best to answer them.

Our research has shown that while the virus is transmitted by aphids, simply controlling the aphids is not an effective measure. All you need is one aphid to transmit the virus to an entire mat. The amount of insecticide needed to keep an area aphid free is prohibitive fiscally and environmentally (detrimental to other insect species).

We have recently found that Heliconia is another host of BBTV and can potentially serve as a reservoir of the virus. The symptoms in Heliconia are virus-like (chlorotic leaves and green flecking of the veins), but not identical to symptoms in banana.

The best thing you can do is eliminate any potential reservoirs of infection and use clean root stock for planting.

I could also suggest growing some sort of tall hedge as a windblock around your banana plantings to help prevent unwanted pests from blowing in on the wind.

Unfortunately there are currently no great control options for viral pathogens.

[Clayjacks]

Great info! Thanks so much.
I’ll definitely hit you up with more questions. And there’s a good bit of heliconia nearby...

[terracore]

Are there any bananas that are more resistant? GMO?

[Mr nice guy]

Are there any bananas that are more resistant?

There are bananas which are proven to be more disease resistant, but I'm not sure if bbtv resistance has been proven yet.

The people who have tons of banana varieties concern me the most because a few of those varieties are surely less resistant.

If you want to grow 30 banana varieties on your property this is something to think about.

Diversity is good...to a point.

[Mr nice guy]

https://www.ctahr.hawaii.edu/bbtd/

[rainyjim]

Unfortunately no resistant varieties exist to date.

BBTV is a DNA virus and the attempts to use transgenic (GMO) technology to transform a resistant variety similar to how the GMO papaya is resistant to papaya ringspot virus have been unsuccessful. Papaya ringspot virus is an RNA virus and the RNAi technique or post transcriptional gene silencing is not very effective for most DNA viruses.

There is some hope however with the new CRISPR-Cas system. Unfortunately bananas take a very long time to transform (make a GMO variety) and the regulatory hurdles in order to make any possible future resistant variety available commercially are substantial. So while this may occur down the road it will likely be quite sometime from now. : /

[Kenney]

I’m seeing it here too, sadly. I’ve been working on cutting down one mat. At least 2 small, sweet varieties are done for and they are the mat I fed all the compost to this year. They should have grown like crazy. It hasn’t spread to the other patches, yet. 30 year old strong mats, probably at least 10 varieties. This is another wait and see situation. I sure hope some varieties survive.

[terracore]

Thanks for the info.

[robguz]

Unfortunately bunchy top is nearly everywhere on the island now, and there's no getting rid of it. Plants can be infected over a year without symptoms. Almost a year ago I had 8 rare ones tested, none had symptoms, but 4 came back positive. No edible bananas that I'm aware of are immune, but there is evidence of resistance, and in rare cases a mat eliminating infection. About the two best options for resistance are Gros Michel and Namwah group cultivars. About the worst are cavendish types. Apple bananas are average and not especially resistant. A friend of mine did his master's thesis on bunchy top while at UH. This involved field trials of dozens of cultivars, though no more than 3 of any type, so statistical significance wasn't reported on and no real science-based conclusions can be drawn. He also intentionally infected cultivars in a greenhouse setting. Gros Michel was one that had an infected mat which later turned up negative. Namwah seemed to have evidence of infection isolation. Normally, if one keiki has evidence of infection, the whole mat in infected. This wasn't the case for Namwahs. This friend is currently farming bananas on Oahu where bunchy top is far more widespread. His take is that even after doing his research project, the disease is quite unpredictable.

My advice is that if a mat has symptoms, and it's not a rare type, just kill it off. My little farm has had infected plants for 18 months, and while production is down vs. last year, I'm still getting a fair amount of fruit. Good care and feeding seems to help, but again, nothing is going to make them immune. Aphids can end up thousands of feet in the air and land elsewhere so I'm not sure a hedge is going to help much.

You cqn get presumably disease-free tissue cultured plants and nurseries, including Home Depot. However, there is no way to guarantee the starts havent' gotten infected while sitting on shelves. Banana growing from now on will likely mean regularly killing and replanting with tissue-cultured stock.

GM is really the long term answer to this and many other banana diseases.