Yew Tree Needles Have Powder Like Substance On Them And Some Needles Are Turning Yellow

Question From: Fresno, California, United States
Q: I have a two yew trees that were professionally planted in a 300 pound stained concrete rectngular planter on 5/30/2016. They now have a powder like substance on the needles in the middle of the trees. They are about four feet tall. They did not have this powder like subtance on the needles when I bought it. I was told to water them everyday since it was hot when they planted them. They put river rock first for drainage and then organic planting soil. Its been in the 90s to 107 F lately. I water them at night. I took a branch to the nursery where I purchased them and he did not know what it could be. Some needles are turning yellow. Please help.
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A: The white powder is powdery mildew - a fungal disease.. You will need to spray the yews with a fungicide such as Serenade. Be sure to spray the undersides of the trees. If your container has drainage holes there was no need for the river rock. When you water, do not get the needles wet. Make sure the root balls are even with the soil surface. Good Luck. Nancy