People ask me how the Panama disease looks like and if it affects fruits and hence humans (short answer: NO)

Fusarium wilt of bananas (#PanamaDisease) kills banana plants. It is caused by the soil-borne fungus #Fusarium.

This is a sick banana in the field (Phil)

Thread 1/n
It is considered to be one of the most important and destructive diseases in history. It caused the epic epidemic in the 1900s that wiped out the "#GrossMichel" (previous cultivar) based industry. Cultivar commercially extinct (still in production in some countries tho)

Before the famous #Cavendish (cultivar we eat now), the Gros Michel was the preferred cultivar for the international banana trade, but it was replaced due to its susceptibility to the Panama disease (let's call it 1st version for now).

Gross Michel "was" preferred because of its great agronomical characteristics such as big bunch, taste, bruise resistant peel and more importantly the ability to resist long trips: from the field to the kitchen.
Gros Michel was as crucial as #Cavendish & virtually (for the world trade) the only banana you could find in the market. It was first reported growing in Martinique (˜1830) then adopted by many in the Caribbean and from there to the world...but then
Pics by @marinamaral2
The first report of this banana disease was from Australia. Dr. Bancroft found bananas with a fungal disease and recognized that it could spread by vegetative propagation.


A bit of the old history of the taxonomy of the fungus that causes #PanamaDisease.
In fact, after 100 years, we still do, what Dr. Brandes did. Either for diagnostics or to find resistant plants. Check this video:

@MyFrogCroaked while preparing my presentation I decided to add some info to this thread. Maybe you are interested. :D
Let's continue!
Once Gros Michel was becoming the king of the fruits, first big losses were reported in Central America (Panama - C. Rica). That's why: #PanamaDisease. The responsible for the disease would be recognized later as FusariumRace 1

Fact: Panama was part of Colombia.
Latest -Not Fun Fact- is important or at least curious.

The 1st report of #PanamaDisease race 1 in America in ˜1890 was Panama (part of Colombia), ˜100 years later (2019) we reported for the first time, the presence or the #TropicalRace4 inColombia.

Many efforts were done to control Race 1, this was just one of them (flooding for disease control), however, even though this worked for some time, this also contributed to further dissemination of the pathogen to other regions.

Gradually, producing #GrosMichel was more and more difficult as Race 1 had expanded to all production areas, by ~1950s GM was replaced by the super Race 1-resistant Cavendish*, not as good as GM but was OK and that was the end of the Gros Michel Era
* is a group of cultivars
Problem solved? Yes, but not forever. What happened?
Well, again, lots of genetically identical clones were used to replace #GrosMichel.
Fact: After more than 100 years, #Cavendish clones are still resistant to Race 1. The same soils used for GM are being used 4 Cavendish
And then boom... #Cavendish showing symptoms of #PanamaDisease again. A new variant know as #TropicalRace4 is described. This strain kills bananas in sub and tropical areas and is rapidly spreading.
OK, we already saw Race 1 and TR4. What about race 2 & 3?

First, let me tell you that #Fusarium SUB-tropical Race 4 exists too. It can affect Cavendish but only under specific environmental conditions and only in the subtropics, however, TR4 and STR4 are genetically different
So what about the other races? Yes, indeed there are 4 races, which are assigned according to the host (type of banana) they can affect, however, in banana the race concept is not a reliable classification. In general:
Before continuing, let's see the symptoms. Externally, chlorosis (yellowing) and sometimes, the pseudostem breaks. Internally, red discolouration of the vascular system.

In this video, you can see how I recover the fungi
I'm spoiling my tomorrow's webinar but let's continue: #Fusarium produces 3 types of conidia (spores). Micro, macro and #chlamydospores. A few are enough to start a cycle of the disease. They are in the soil and sick plants.

#panamadisease #SEM #tropicalrace4
#fusarium spores attach to the roots, germinate and penetrate. It grows in the vascular system and is rapidly distributed via the xylem. It continues to grow and blocks the vessels causing wilting as the plant can't eat/drink. Later the plant collapses and die.
All those empty burned spots were plants that were eliminated. The worst part is that we can't control it (not even with fungicides) and there is not replacement for Cavendish yet. Many scientists working on it.

But let's continue with the story
#TropicalRace4 has been threatening global banana production since the early 90s but lately, the number of reports increased. In 2019, was reported for the 1st time in LatinAmerica triggering the alarm for the whole region (banana producing area)…
How does Fusarium (#Panamadisease) it easily spreads in 3 ways:

- Plant material (suckers, plant parts)
- Soil (shoes, tools, machinery, etc, etc.)
- Water

These are positive #TR4 colonies I recovered from soil samples from shoes.
Well, thanks again for your attention, that's it for today! Maybe, I will add some more later, but if you have questions about this, just let me know.

You can always see more exploring #TheHistoryOfTheBanana and the #PanamaDisease

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