By India
Kent,
United Kingdom 
My weeping Willow (about 15feet tall) has some yellow leaves with a black spot. There is no evidence of insects of any kind. Many leaves fell off last year leaving the tree almost bare. I am giving the tree 4 gallon of water per day to help it this year as it has many trees surrounding it. Its been in position about 5 years. Could I be overwatering? Thankyou for your help.
12 May, 2011
Answers
Its probably willow leaf spot, i have seen this quite often on large trees, some years the foliage is good and some years are very infected, it is a fungal problem, and you could spray your small tree with a fungicide if you so wish, but large ones its a case of living with it, julien.
12 May, 2011
Thankyou Beattie & Julien for your replies. I will spray with fungicide. Regards- India.
13 May, 2011
Previous question
« Sorry. here's the close-up photo I should have included on my question.
As they grow on riversides - often with their roots in the water, I'm sure it's not possible to overwater weeping willows. Sorry I don't know what's making the yellow leaves with black spots, but overwatering isn't it.
12 May, 2011