Bottle Trees Dropping Leaves Probably Water Related

 Q. My purpose for writing is that the bottle trees that I planted last year and until now have thrived, have suddenly been stripped of all of their leave at just the very top. The rest of the trees and the leaves look healthy. I live in a very windy area, and my landscaper suggested that the wind stripped the leaves. I have doubts that this is the case since my next door neighbors' bottle trees which are the same age look perfectly healthy. The trees have been been watered on a drip system twice a day, three time a week for the past month. I have 10 trees that look like this. Any advice will be greatly appreciated.

Bottle trees can drop leaves if they are too wet. They grow along streambanks in the dry parts of Australia.

A. From the sound of it and the pictures you sent it sounds more like a watering issue – the soil staying too wet between irrigations. Bottle trees have sensitive roots to wet soils…the roots will easily suffocate if the soils stay wet. This type of overwatering can be seen in the tree by its loss of leaves. Unfortunately we often see the same results when the tree is not given enough water but I don’t think that is the case with your tree.

Right now (Late spring, April) we should be watering trees and shrubs once or maybe at the most twice each week. When temperatures get warmer in about May or June is when three times a week watering is most common. Depending on the soil and its drainage would determine if watering three times a week is okay now. Watering that often this time of year would be okay for very sandy soils with very good drainage.

You can find out if the tree roots are ready for another irrigation by using a soil moisture meter stuck in the soil.

https://xtremehorticulture.blogspot.com/2018/09/use-houseplant-moisture-meter-to-know.html

https://xtremehorticulture.blogspot.com/2018/04/when-to-change-irrigation-clock-and-how.html

https://xtremehorticulture.blogspot.com/2018/12/moisture-meters-and-rebar-tell-you-when.html

https://xtremehorticulture.blogspot.com/2013/07/bottle-tree-dropping-leaves-could-mean.html

https://xtremehorticulture.blogspot.com/2013/05/bottle-tree-with-dying-branches.html

Consult this expert on Bottle trees growing in the Phoenix area:

http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/brachychitonpopulneus.html