Wednesday, April 24, 2019

National Arbor Day

National Arbor Day is celebrated on the last Friday of April, which is April 26 this year. Texas celebrates Arbor Day on the first Friday of November however. This is because in Texas, November is a less stressful time for trees to be planted than just before summer arrives. As long as soil temperatures are above 40 degrees, root growth should occur and help a newly planted tree get established before the heat and drought stresses of summer arrive.

So instead of urging my Texas readers to celebrate National Arbor Day by planting a tree, I thought I would share some information about some weird looking growths you might spot on your oak trees. The growths are called galls and there are several different ones in a variety of colors and sizes. Often a very tiny wasp (by classification, not the standard insect you think of when seeing the word wasp) laying an egg on the tree is cause of the galls. Fortunately this is one growth on your trees that you do not need to get worked up about. The appearance of galls is often cyclic and even though the wasp causes the tree to grow a protective gall around the egg it laid, very little resources are diverted from the tree to cause it any problems.

How did I get thinking about galls and decide to write about them as part of a celebration of trees? Almost two weeks ago a neighbor asked me about some light green growths on her tree that were a bit bigger than a golf ball. I told her they looked like oak galls and were most likely nothing to worry about. (Although I must admit they were bigger than the ones I was used to seeing.) I told her I would take some pictures, do some research and write up a blog post about them. As I was working on this task, I realized that it was almost National Arbor Day and it made sense to me to combine the two into one post. It turns out those galls are oak apple galls for their resemblance to apples and they can be found on some varieties of red oaks. While doing my research I found two good, Texas based articles if you want to do more reading on this subject. One is from Texas A&M Agrilife Extension and the other is found on Neil Sperry's Gardens.

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