What’s the matter with yew? A case study

“A garden is a grand teacher. It teaches patience and careful watchfulness ... ” 

— Gertrude Jekyll, “Wood and Garden,” 1899

Just as Gertrude Jekyll noted more than a century ago, gardeners continue to learn the importance of close observation so they know and enjoy their plants more fully and become aware of problems quickly.

Dame Jekyll went on to say that a garden also “teaches industry and thrift,” and these two qualities are particularly important when gardeners attempt to identify pest problems. Certainly, diligence and caution are needed in equal measure for unraveling mysterious garden concerns without resorting to extremes (such as yanking out the affected plant immediately or applying harsh chemicals).

The OSU Extension Service suggests a series of questions to analyze plant problems from multiple perspectives. The questions were useful recently as I studied a yew (Taxus baccata) in my front yard that has turned brown.

1. Does a real problem exist? Yes, yews are evergreens and should not be turning brown.

2. What is the population of plants, and how many are affected? I have six yews in a hedge alongside my driveway, and one of these is affected now.

3. What other types of plants have been grown in this site? The yews replaced some straggly rose bushes that were not getting enough sun.

4. What are the cultural conditions of the affected plant, and are these conditions different from unaffected plants? All of the yews are on the same drip system and are planted in soil amended with compost. (Yews grow well in a variety of soils as long as they are not wet.) The affected yew receives more direct sunlight than others that are partially shaded by trees. (Yews are supposed to grow well in sun or partial shade.)

5. When did the symptoms appear? I noticed the shrub was beginning to turn brown in August.

6. Is the problem new or has it occurred before? It’s the first time this yew has had any problems; however, the yew in front of it turned brown the summer before, so I cut it back to less than half its size and it put out lots of new growth this year. (Yews handle hard pruning pretty well.)

7. Have any pesticides or fertilizers been applied recently? No, just compost last spring.

8. Could weather or other environmental conditions be a factor? Yes, in July and August, we had 35 days of temperatures 95 degrees or higher and very little rain.

9. What part of the plant is affected? Some of the leaves have turned brown, but I don’t see a problem with the branches or central stem. Looking closer, I see that the some of the needle tips are brown and the discoloration moves inward.

10. Are the symptoms spreading, improving or constant? The foliage turned browner through September; however, I noticed the yew has begun to put out some new growth since we’ve had more rain.

11. Are there any signs of a pest present? I looked with a magnifying glass and did not see any insects or signs of disease.

12. What insights have you gained from your responses? First, the fact that the yew is sprouting new growth tells me it’s still alive. Second, the brown needle tips look burned to me. This yew is not shaded by trees as are the other yews in the hedge; in fact, it receives more direct sunlight now that I cut back the yew in front of it.

After my analysis, I think the yew was damaged by over-exposure to the hot summer sun. My strategy is to cut it back and see if it puts out new growth next spring. I’m also going to build an arbor in front of the yew hedge that will protect the plants that are not shaded by trees.

All of this brings me back to Gertrude Jekyll’s observation about gardens teaching us to be patient and carefully watchful. I’ll keep an eye on my yew, and I’ll keep in mind what Jekyll said is the last lesson a garden teaches, and that is “it teaches us entire trust.”

— Rhonda Nowak is a Rogue Valley gardener, teacher and writer. Email her at rnowak39@gmail.com. For more about gardening, visit her blog at http://blogs.esouthernoregon.com/theliterarygardener/

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