YELLOWING CLEMATIS DUE TO WEATHER; DOGWOOD DAMAGED BY WINTERKILL
Q Can you tell me what is happening to my alpine clematis? A yellowing pattern has appeared on an end section of a 10-foot screen of the plant in my backyard. I don’t recall seeing it ever before. The plants are several years old, face north and have always done very well, with lots of normal leaves and flowers this year as well, but I am worried about this new development.
A From your photos it appears the yellowing is along the veins of the leaves. There can be several reasons for a clematis leaf turning yellow, such as a magnesium deficiency or other nutrient problem. However, since this is a well-established plant and the issue is only at the very end of the vine I would suspect that this is likely a weather or environment-related issue. I would monitor the yellowing and if it starts to spread we can talk again.
Q I have a dogwood that did not come back well this spring and I’m wondering if it was winterkill or possibly some other disease. I also have two Nanking cherries about eight feet away from it. One of those had a lot of die-off in the centre last year, don’t know if this is where something started? I did not see any problems at the end of last season ( black spots or shrivelling leaves). I had some powdery mildew on a squash plant last year that was several feet away but the wind could easily have carried that. I would like to know if I can just cut the branches out or if it would be best to cut the whole thing back to the base and let it come again. I have grown dogwood for years in Calgary and have never had any issues with winter kill so I’m concerned it is something more serious.
A From your photos the dogwood appears to be an older, well-established plant. Since you saw no evidence of the powdery mildew on the dogwood last season I doubt that is the issue. Without looking at the plant my best guess is that the issue is winterkill. Remember that winter winds can be lethal. Having said this, the rest of the plant looks to be very healthy. If it were me I would remove all of the dead branches from the centre of the plant and let the plant fill in on its own.
Q We have a nice Russian olive tree in our backyard that a downy woodpecker has now found. Will this woodpecker damage our tree, as there are multiple rows of holes in it now? Is there a solution? Hanging plastic owls just made it go higher up the tree.
A If the woodpecker continues to drill holes in a circle around the trunk and girdles the trunk it could damage the tree. I would try hanging aluminum foil strips to scare it away. Or you can try offering it a food source such as suet, hung in a location away from the tree. I’m afraid there is no tried-and-true method to control the problem.
As I continue to work my way through many gardening questions sometimes I run across one that just brightens my day and I would like to share:
“I wanted to give you some feedback on your advice earlier this year on red lily beetles. It is working so far.
“Last year I just did coffee grounds as mulch and was not really aggressive. Total fail. This year, I sprayed with Dr. Doom as soon as the lilies started to emerge. Then I started laying on the coffee grounds, a good two-inches thick around and through them all. Since then, nothing.
“I have seen no sign of the lily beetle. This is such a change from last year; they were decimated at this point. I always look forward to seeing your column in the Edmonton Journal and I hope you know how much you are valued as a local expert. There are thousands of gardening books out there, but nothing beats advice from someone who understands this corner of the world. Cheers to you, and thank you for all you do.”
Good luck and happy gardening!