yellowing leaves on Weeping Mulberry Tree

viriatus starts with ...
Just a query about my Mulberry Trees which i had purchased about 5-6 mths ago.
My trees were looking fine at one stage then alittle over a month ago, i started noticing that the leaves were turning from a dark lush green to a light lime colour and that the leaves also started turning yellow with browning along the edges.
Initially i assumed it was due to the onset of Autumn, but i noticed that my brothers trees, which he had purchased at the same time were still a lush dark green.
I have been watering once a week for about 25 mins with my garden hose at medium flow.
Now im not sure if it is a problem of too much watering or not enough as i have read on some sites the problems that can be caused by overwatering. The soil type in my area is clayish. Look forward to your response.

Much appreciated
John M.

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Jantina says...
25 mins would not be too much on sandy soil but clay holds the water very well and the hole you dug may be acting like a water holding dam, on the other hand I have noticed a marked difference in the timing of autumn foliage within a fairly small area depending on the microclimate.