Some personal plant notes from the drought of 2021 on Cady Mountain.
What I’ve learned from the lack of rain this summer is that I planted some trees in the wrong spots. We are on the south slope of Cady Mountain in the middle of San Juan Island. The rocky outcrops, which retain heat, plus the relatively thin soil are not the best places to plant Douglas maples (Acer glabrum var. douglasii) and Oregon ash (Fraxinus latifolia) – especially if it’s going to get hot like this in future summers. On a more happy note, two of the Oregon ash I planted were in low spots, with much deeper soil and a more reachable water source, apparently, because they are still green and growing more rapidly than their desiccated friends.
You can see the maples in the middle of the photo on the right (above) – their orange color makes them stand out and is beautiful in the fall, but this year they turned orange way too early. And look at the snowberries in the foreground! You know it’s dry when even the indigenous snowberries turn brown.
I have seen many more acorns on the Garry oaks (Quercus garryana) this year. Hooray! But, as you can see in the photo above, the Oak Leaf Phylloxera (Phylloxera glabra) is present as well. This is an aphid-like bug that sucks the green out of the oak leaves, leaving them spotted and brown. Gross!
We started noticing Phylloxera on one particular oak in 2011 (the oak on the left in above photo). That oak is still with us, but since then, about 3 other large oaks have been afflicted. I learned to not worry too much about this (although I still do) from our friends in Victoria, Canada: the Garry Oak Ecosystems Recovery Team (GOERT). They are a very helpful resource. Check out their website, and this page in particular, which discusses the Phylloxera and other pests.
In a recent email exchange with the Recovery Team, I received this information about Phylloxera:
The winged insects in your photo are also Phylloxera. Like aphids, they have a life cycle that includes a sedentary phase that just sucks sap and a winged phase whose job it is to mate and move around and lay eggs.
Some individual trees are more susceptible to damage by Phylloxera than others. I don’t think the reasons are known. The same is true for the jumping gall wasp, which also causes early browning of oak leaves. I have one tree in my yard that looks like it’s slowly dying from insect attack and half a dozen others that are totally fine. Hopefully your trees will pull through. I’m getting some new ones started at my place so that there may be replacements when the mature trees eventually age out or succumb to insects.
Hope this information is helpful to some of you Camas Club mates! –Shaun