thaibanana

I am wondering if there is a cure/treatment for Sigatoka?

Some of my plants are showing signs other doing quite well.

I have been cutting off affected leaves but would like something a little more.
I have heard of spraying a fungicide but have no clue what to buy as i am in thailand and here they just put them in the ground and if get banana's ok.
They dont care if plants are yellow leaves and do not fertilize.
Any help?

Nicolas Naranja

Propiconozole
Azoxystrobin
Tebuconozole
Pyraclostrobin

Copper Sulphate
Banana Spray Oil
Serenade

They aren't really cures, but they will keep it at bay.

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Some people go bananas, I went plantains.

shannondicorse

thaibanana,

i'm in the tropics like you are.

here are some general tips:

1) fertilise. K & N are very important to bananas; resistance and yield improve with fertilisation. Don't apply fertiliser excessively..it's expensive!

2) micronutrient status is important... you don't have to use commercial preparations; if you know a little chemistry

3) stay AWAY from monoculture... run a highly polyclonal field ...include as many vars as possible. you're in Thailand!!!... there are really many vars there.

4) "inoculate" the field with leaves of ordinarily Sigatoka susceptible plant varieties (e.g Cavendish vars) from nearby anomalously "resistant" fields... in many such instances, a "beneficial" leaf surface microflora has developed to thwart Sigatoka.

I've seen this for myself.

These are cheap methods that a small farmer can use... in addition to good field sanitation & field planning.

there are more...


shannon


shannon.di.corse@gmail.com

Nicolas Naranja

I have a highly polyclonal field, I have 30+ varieties on 0.25 acres and while I am sure I am having less problems than I would if I had a solid planting of Grande Nain, it isn't perfect. I've had to put out a lot of serenade and copper and do quite a bit of deleafing.

The best option is to find a resistant variety. I have some cavendish interplanted with FHIA-17 out on my 2.5 acre farm and I can pick them out strictly based on the sigatoka.

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Some people go bananas, I went plantains.

Kat2

So are banana circles (monoculture but spaced 7 to 8' apart and no circles using same types next to each other) mixed with other plants such as lemon grass, sweet potatoes and even tomatoes a recipe for disaster? NE Florida doesn't appear to have the same disease issues as further south but it's probably just a matter of time before they get here so I'd like to prepare.

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shannondicorse

Kat2,

I have some advice wayyy below in bold red. It might be more strictly applicable to tropical plantings than the more temperate areas. I realise it is very contrarian! I apologise in advance.

shannon

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CAUTION, LONG RESPONSE.

I'll tell you what I've found, as a hobbyist, not as a scientist; because if I had to do a scientific study it would take up far too much of my time and energy to be worthwhile to me. It would take away the adventure too! And that's 50% of life.

GENERAL BACKGROUND: As I see it, Black Sigatoka is a problem in the peculiar pathoecology of bananas (the term "pathoecology" is valid, but I'm expanding its usage here - by a mile!).

Black Sigatoka (Black Leaf Streak - BLS) is not the only problem that is facing bananas. To be sure, many serious pest & disease problems - some known, some foreseeable, some totally out of the blue - will hit bananas again and again within the next 30 -50 years.

The pathoecological foundations of banana disease problems are:

1) that bananas have moved from being a polyclonal horticultural crop to being a monoclonal agricultural field crop within 50 years (very late 19th Century - mid 20th Century).

2) the original donors of the A genome to domestic bananas were island subspecies of Musa acuminata; which, as island species are wont, did not accumulate anywhere as many genes for disease resistance as South/South East Asian acuminata subspecies

3) new cultivar groups traditionally came into existence from the fertilisation of wild and "cultiwild" seed bananas surrounding and associating with swidden fields by pollen from domesticated bananas introduced into and grown in swidden fields

Selection and somatic mutations over centuries (sometimes millenia) allowed substantial changes in plant and fruit morphology, agronomic and fruit characteristics and some disease resistance; but the actual genetic diversity in an entire lineage resulting from a single fertilisation event is unacceptably poor by modern field crop standards

4) bananas in the field are now a crop divorced from their genetic disease resistance heritage. Evolution of crop bananas is now dead

5) banana pests and pathogens evolve at a rate that is far faster than to which breeders can respond

6) worldwide movement and population expansion of banana germplasm, pests and pathogens is potentially millions of times faster than it was 200 years ago

7) there is nothing in current field monoculture of bananas to allow for a disease "resistant" or disease "adaptive" pathoecology to establish itself

8) the current breeding paradigm is to breed specific resistance into popular cultivars - or to new types that are poor substitutes for older susceptible cultivars. This represents the wholesale application of an inappropriate resistance breeding paradigm (costing lots of money!) from other crops to bananas - going on 90 years now!

When will we learn?


WHAT I'VE NOTICED ABOUT BLS:

a) aggressive disease is not in the "interest" of the BLS pathogen and the most aggressive strains, i.e., those that rapidly kill most of the leaves (and plants) have less survival advantage than those that are less fulminant - providing the latter strains of the pathogen have the opportunity to actually be selected in the banana population.

b) aggressive disease is not in the "interest" of the rest of the banana live leaf microflora either - given the opportunity, they will evolve to check the virulence of deleafing diseases.



WHAT DOES THIS MEAN TO A FARMER?

i) Grow 80% by number of tolerant/resistant strains of bananas - as many varieties as you can find - and only 20% of the susceptible (...generally they'e the choice varieties that you really want) this allows more benign BLS and competitor bacteria & fungi have population reservoirs on which evolution will work

ii) fertilise well - remembering that Potassium, trace metals and assimilable silica are critically important

iii) hunt for fields of BLS susceptible varieties displaying paradoxical resistance. Transfer live leaves of such material into your fields as inoculum

iv) gradually restrict ( titrate) your deleafing activities (over the space of maybe 2 years)

vi) do not use fungicides... "SERENADE®" might be rather ok though... and might well play into your strategy... THIS IS NOT A PLUG FOR SERENADE...


I note that you're seeking to do a somewhat similar thing... watch the BLS susceptible/BLS tolerant-resistant ratio... keep it at least 1 to 4 for quickest results...

Kat2

Thanks, Shannon. I'm a very old "organic" (read: lazy) gardener who tries to let nature take her course; she's a smart cookie if you don't fight her. I have always tried to companion plant and mix it up even in a small space but inevitably ended up with powdery mildew on susceptible varieties. (I suspect that's very similar to tropical plant diseases in that it cripples the plant, ruins the crop and eventually kills the host. Obviously with annuals you don't have the same investment as you do with bananas but the result is the same.)

After years of using no pesticides or fertilizers in the city (had leaf rich mould and praying mantis nests everywhere), I moved to OH and was told to that it was best to let weeds grow because the bugs preferred them. I fought it but apparently it's true. And I never had powdery mildew in 3 years gardening there. Odd.

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