Australian Bottle tree losing its leaves
We planted a large box 50 gallon Australian Bottle tree in November , Gilbert AZ. Tree has done very well up through end of May. Hotter temps in June leaves started turning brown and dropping. Tree is in full sun, 1-gallon of water per day
Certified GKH Gardening Expert
It is hard to know without seeing the damage, but it could be a few things depending on how it looks, and where is occurred first.
I would say, as long as the soil had time to dry out completely each day, that it is likely to have used up the nutrients in the soil. Especially if this is sandy soil, or clay. You may need to fertilize.
If the soil did not have time to dry out completely between watering, then it may have contracted an infection. Most trees that are able to store water, such as these, will overcome the infection on its own.
You can help it along by using DOLOMITIC LIME and WETTABLE SULFUR once per year, or if this happens in the future.
This article will give you information on the proper care of the trees: https://www.gardeningknowhow.com/ornamental/trees/bottle-trees/growing-kurrajong-bottle-tree.htm