Bananas turning black on the plant.

[stubuzz]

As you can see the black starts on the bottom of the stalk and spreads upward. I have cut off the black part but it seems to be inside the stalk. Any ideas?

[IsaanAussie]

Hard to tell when you only have a few bananas (a hand rather than the whole bunch). Can you show this on the whole plant? Bananas skins darken as they ripen naturally. What type of banana are they?

[Damrongsak]

A few possibilities here:  https://plantvillage.psu.edu/topics/banana/infos

[drtreelove]

37 minutes ago, Damrongsak said:

A few possibilities here:  https://plantvillage.psu.edu/topics/banana/infos

That's a great paper, thanks for posting. 

I don't see the specific disease condition that fits the signs from Stubuzz's plant and I haven't seen this myself.  Although from what is shown I suspect a fungal disease. Maybe the "cigar end rot" or similar infection. So following some of the "management" tips for the other fungal disease's presented will be your best bet at suppression. 

 

Management (anthracnose)

Commercially produced fruit should be washed and dipped in fungicide prior to shipping; protect fruit from injury; remove flower parts which can harbour fungus.

 

Management (cigar end-rot)

Infected flowers should be removed from the plant; bunches should be bagged using perforated polyethylene; chemical control may be necessary in the case of severe infestations.

 

I don't think you will be able to eradicate the disease from the subject plant without extraordinary measures of systemic fungicide treatment, but you may be able to prevent the spread to other plants by utilizing sanitation, removing the infected plants and plant parts, clean up of infected leaf litter to reduce spore load and reinfection, and addressing the growing conditions, soil fertility and water management.  And if you have budget and spray equipment, maybe consider applying a biological fungicide regularly until the growing conditions and fertility can be improved enough to promote plant resistance to disease. 

 

"Banana plants grow optimally at 27°C (98.6°F) and require a deep soil, rich in organic matter which is well draining and well aerated. The plants will grow optimally in soil with a pH between 5.5 and 7.0."  

 

This is hard to achieve if you are starting with an alkaline, heavy clay soil common in many areas of Thailand. I haven't grown bananas commercially, but have always grown them in home gardens at several locations in Thailand. I have been lucky with no serious plant pests or diseases, but I go all out to create best fertility that I can, don't over-water or under-water, once a week deep watering during dry season.  I plant in best location that I can for drainage, with composted backfill, mulch heavily, and apply aged or composted manure fertilizer. I don't let stems stand and rot after fruiting, I cut them out and compost them, minimizing fungal stem rot inoculum for remaining plants. 

[drtreelove]

example:  cigar end rot

 

https://www.plantwise.org/knowledgebank/datasheet/54408#PreventionAndControlSection

 

"Control is primarily by sanitation and avoiding damage to host tissues (Meredith, 1960; Beugnon et al., 1970)"

 

IssanAussie is right, its always best when presenting photos of plant problems, to include pics of the entire plant and the site. Include your geographical location and description of the growing conditions, soil and water management, commercial grow or home garden and how many plants are affected. 

[stubuzz]

This second picture is the plant the bananas came from in the OP. It is in my garden in central Thailand. The soil is mostly heavy clay which can get waterlogged for a few days after heavy rain.

I considered cigar end rot, but the blackening starts at the opposite end.

The first  picture is a bunch on the other side of the garden that is turning black. The blackening starts from where the main flower is cut.

[IsaanAussie]

Can I ask why the flower was cut off in the first picture? It appears to be a very small number of hands, like there would have been more bananas to come. 

The second picture (could just be the picture colouring) gives me the creeps. Your soil is green! That banana next to the pathway IS the drainage point. Do you have any compost or use any EM? Bananas are pretty heavy potassium users as well, what are you feeding them with?

Sorry more questions than answers... but I think you may have some basic soil bound issues.

[stubuzz]

I didn't cut the flower off, but i suspect the black bananas are the male fingers or it was cut to stop the plant from tipping over. It was probably a sucker.

The green soil is weeds sprouting after the rain. The garden is large and the weeds grow faster than they can be removed.

I gave all of the bananas a spray with a fungicide today and i'm going to cut and burn all of the damaged plants and fruit at the weekend.

FYI- some of the fruit on nearby plants are unaffected.

[Tayaout]

I have no experience with banana but plenty with fungus. Fungus are very sensitive to PH. Sometime a couple treatments with a spray composed of sodium bicarbonate with 1 drop (tiny amount) of dish washing soap is sufficient to kill them. It's more gentle than a fungicide on the beneficial mycorrhizae present in your soil. 

[Isaanbiker]

23 hours ago, IsaanAussie said:

Hard to tell when you only have a few bananas (a hand rather than the whole bunch). Can you show this on the whole plant? Bananas skins darken as they ripen naturally. What type of banana are they?

Perhaps these are African bananas? ( Sorry, not being racist ) Is it possible that they get too much water, or not enough? 

[IsaanAussie]

Just now, stubuzz said:

I didn't cut the flower off, but i suspect the black bananas are the male fingers or it was cut to stop the plant from tipping over. It was probably a sucker.

The green soil is weeds sprouting after the rain. The garden is large and the weeds grow faster than they can be removed.

I gave all of the bananas a spray with a fungicide today and i'm going to cut and burn all of the damaged plants and fruit at the weekend.

FYI- some of the fruit on nearby plants are unaffected.

OK suckers are the way bananas propagate. That one I would have removed simply because of its location. 

I work on the principle of grandmother, mother and daughter in one location, removing the rest of the "suckers". Use them somewhere else where they have better drainage etc... 

Bananas are one of the hardest things to compost because they contain antibacterial and antifungal properties. I don't believe they need help with either, they just need the right soil conditions and nutrients. 

[IsaanAussie]

Just now, Tayaout said:

I have no experience with banana but plenty with fungus. Fungus are very sensitive to PH. Sometime a couple treatments with a spray composed of sodium bicarbonate with 1 drop (tiny amount) of dish washing soap is sufficient to kill them. It's more gentle than a fungicide on the beneficial mycorrhizae present in your soil. 

You are getting close, I don't use any chemical sprays but maybe yours is good. I am very careful with making compost with the right C:N ratio and the right pH level. The first is a best guess on component levels, and the second I measure. I try to get the C:N up to 35 to 40 (wisdom says 20 when finished) because I believe nature will balance things out by allowing N to be lost if in excess and that is the last thing I want. Everything living is made up of carbon. A pH of 6.4 is good for most plants. The biology must also be in balance, I use EMA for that during the composting. 

Using compost in the planting zone for a banana and as a mulch and I can have fruit within 6 to 9 months.

[bannork]

I don't think I have ever seen a multi-hand banana tree in Thailand. Am I just unobservant or is the soil an obstacle, or is that particular species of banana hard to find?

 

[stubuzz]

20 hours ago, bannork said:

I don't think I have ever seen a multi-hand banana tree in Thailand. Am I just unobservant or is the soil an obstacle, or is that particular species of banana hard to find?

If you water and feed regularly, you will get bigger crops.

[LivinLOS]

 

[drtreelove]

I believe story is in reference to fusarium wilt (Panama disease) in the large commercial monocultures of Cavendish bananas. And not likely to be related to the OP issue.  

 

http://www.promusa.org/Fusarium+wilt