Durian fruit falling off the tree

[djayz]

We bought a bit more land just over a year ago and on this land the owner had planted about 20 durian trees (plus mangosteens and rambutans). All from seed. 

Anyways, this year was the first year that one of the durian trees actually starting bearing fruit (see photo) about 1 month ago. I checked the tree again a few days ago and all the newly forming fruit is gone! Same on the brother-in-law's land (adjacent to ours, also planted by the same man and also from seed as ours). All his durian fruit has also fallen off the trees. Nobody seems to know why and the closest I got to a plausible explanation was "perhaps too hot". 

Any durian growers/experts out there who can proffer an explanation? 

Just for info, the trees in question haven't been fertilized or watered (the water table is quite high where we are, so I assume that they are getting adequate water). 

 

 

[Pogust]

Don't know about durian, but I see young trees trying to produce the first year not developing fruit. I think they are still too young and need to grow bigger before having enough energy to produce fruit. Jackfruit having only a few male flowers first year, then female also the next and producing.

[drtreelove]

 "...the trees in question haven't been fertilized or watered (the water table is quite high where we are, so I assume that they are getting adequate water)..."

 

How does that saying go? "To assume makes an ass out of you and me".  A high water table does not insure that trees are getting what they need, or are not getting too much. Soil surface watering is important in most cases because that's where the bulk of the absobing roots are, in the top few inches of the soil profile, and just as important is, that is where the beneficial soil biology is active (or should be active) in facilitating nutrient cycling and other important metabolic functions.

 

And sometimes the opposite is in effect, that a high water table is too much and predisposes root rot in trees that are highly susceptible, like durian and avocado. 

 

Also, regarding soil fertility, durian trees have a high foliage density and large structural wood formation, and large fruits, so there is naturally a need for high nutrient availability, and in the depleted soils of Issan, that usually means that well managed amendments are needed until soil biology can be restored. Calcium supplementation will be one of the most important, and in the CEC-based BCSR soil testing and cation balancing system, for large fruit formation, Potassium is upped to 5%, as well as other essential mineral considerations. SOM (soil organic matter) content, mulching or cover cropping, are also important management factors to consider. 

 

You are working with a highly unnatural planting, so you should not assume that natural forest conditions prevail, and that intelligent soil and water management is not vital. 

 

Also, trees planted from seed are not necessarily true to the parent variety that has been bred for adaptibility to the site specific conditions and desireable characteristics, so anything is possible. 

Edited April 12 by drtreelove

[djayz]

On 4/12/2024 at 8:26 PM, drtreelove said:

 "...the trees in question haven't been fertilized or watered (the water table is quite high where we are, so I assume that they are getting adequate water)..."

 

How does that saying go? "To assume makes an ass out of you and me".  A high water table does not insure that trees are getting what they need, or are not getting too much. Soil surface watering is important in most cases because that's where the bulk of the absobing roots are, in the top few inches of the soil profile, and just as important is, that is where the beneficial soil biology is active (or should be active) in facilitating nutrient cycling and other important metabolic functions.

 

And sometimes the opposite is in effect, that a high water table is too much and predisposes root rot in trees that are highly susceptible, like durian and avocado. 

 

Also, regarding soil fertility, durian trees have a high foliage density and large structural wood formation, and large fruits, so there is naturally a need for high nutrient availability, and in the depleted soils of Issan, that usually means that well managed amendments are needed until soil biology can be restored. Calcium supplementation will be one of the most important, and in the CEC-based BCSR soil testing and cation balancing system, for large fruit formation, Potassium is upped to 5%, as well as other essential mineral considerations. SOM (soil organic matter) content, mulching or cover cropping, are also important management factors to consider. 

 

You are working with a highly unnatural planting, so you should not assume that natural forest conditions prevail, and that intelligent soil and water management is not vital. 

 

Also, trees planted from seed are not necessarily true to the parent variety that has been bred for adaptibility to the site specific conditions and desireable characteristics, so anything is possible. 

Thank you for the feedback. I thought about the lack of watering too, but the BIL, who planted grafted durian trees years ago and definitely waters them regularly, is having the exact same problem. Fruit just falling off, despite having had some fruit last year. 

Missus says it's "too hot". While it is hotter than usual, I fail to see how the extra degree or two can cause the trees so much stress.