Question
QUESTION: I am a landscaper in Atlanta, Ga. Planted several Willow Oak trees 2-3 years ago in an irrigated area.  Noticed about 10% of them are turning a bronze color. Saw no evidence of insects, but did notice some margins around some spots on teh leaves.  Is there some disease these trees get?

ANSWER: Does not sound like fungi disease. Usually if the leaf margins are turning it is some environmental problem. Either planted too deep, too much  or too little water. The drought in the South the last three years is more than likely the problem. Oaks like to grow good root systems when they  are first planted and in the process they cut back on the leaf growth which can show up as small leaves or dying leaves. This process lasts form 2-4 years.

A tree needs about 1 inch of water per week---place a pan under the tree and check the amount of water the sprinkler is putting out -if the pan has 1 inch of water in it the water is good for that week. If the system is running more than once a week and putting out water less than 1 inch then the roots tend to grow shallow and when there is a break in the water supply the leaves will turn. A once a week watering of 1 inch is called deep watering and encourages deeper root systems. Hopefully there has been no herbicide applied near the tree (Weed and feed fertilizer contains a herbicide that will kill trees especially those under stress).



---------- FOLLOW-UP ----------

QUESTION: Some trees have done fine while others next to good ones look fine.  We have been in a bad drought with water restrictions.  The trees were dry last summer.  It will be a hard sell to blame the drought when others next to the bad ones look good.  Suggestion?

Answer
Planted too deep??
Dog Urine??
Poor planting job??
All just guesses without seeing the trees it would be hard to exactly ID the problem.
Try calling the Ga. Forestry Commission and ask one of their Foresters to come out and take a look. Their number should be in the phone book. This is a free service.
Sorry that is about all I can think of for likely causes.