Prescription for sick rosemary?

sick rosemary bush
Photo credit: ask an expert
Q:

I have several nice rosemary plants on my property, but lately some of the branches/plants have completely died. Initially the leaves become bright yellow and then turn graybrown. It almost looks chemical from the results I've seen of Round-Up use. Is there any way to find out how they are dying? Plants and branches right next to the dead ones look quite healthy.

- Lane County, Oregon
A:

Rosemary plants had a hard time with the cold winter temperatures this season. I have a few in my own yard with the symptoms you describe. Much of the plant is still alive and will grow fine this summer. Plants such as this will loose some older leaves as they are not retained forever. But the amount of leaf loss and death of branches is unusual and due to the winter freeze. 

Jay Pscheidt
Professor of Botany and Plant Pathology
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