QUESTION: I have 2 Raymond or Raywood ash about 20 feet apart. Last year one lost it's leaves well before the other. Both were fine this year. Now that same tree is starting to loose leaves now.
ANSWER: This is due to genetic variation. Both are the same species but have a little different genetic make up that will change the timing of the leave fall an usually budding out in the Spring. Nurseries will cross breed trees to get characteristics that thy like such as the red foliage in the Fall. this crossing may change the timing of the leaf turn and the budding out in the Spring. Nothing to worry about just enjoy.
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QUESTION: this didn't happen in the first 12 years. the trucks look the same. can it be getting to much or not enough water? underground water?
They should be getting about the same amount of water unless the area around the tree in question has changed and there is more water staying OR being taken away from the area. That is about the best I can do without seeing the trees and where they are planted . Sorry.