Week 6 at Wilbur-Ellis

Week six of being a scout at Wilbur-Ellis went pretty well. We are getting closer and closer to harvest every day and it won’t be long now before the orchards are full of workers and harvesting equipment. In the meantime there is still scouting to be done. This week I want to focus on what I have learned about a particular pest by the name of San Jose Scale.

San Jose Scale(scale for short) is a tiny insect that latches onto the tree with its mouth and sucks on the sap. To show you how small they are I provided the picture below. Inside the yellow oval is a whole cluster of scale. They are very hard to see in a picture but in this form they are tiny grey specks with black dots at the center. If you look towards the bottom part of the branch you will see what the branch is actually supposed to look like. As you move up the branch you will begin to see more and more scale.

scale 1

Scale is a very tough insect to kill. They spread quite rapidly and are hidden within a kind of shell. This shell protects them from sprays that can kill them. The spray is really only effective at certain times which makes this a tough pest to get rid of. Scale can attach to a lot of different trees but interestingly it will not attach to sour cherry trees, only sweet cherry trees. There is something in the makeup of a sweet cherry tree that the scale likes. I have seen sweet trees with scale right next to sour cherries that go unaffected. Scale in sweet trees can be a real problem if they are not killed soon enough. The picture at the bottom is of a sweet block that has extensive scale damage. You can see how the trees have almost no leaves on them. This particular sweet block is of the Gold variety so you should see nice golden yellow clusters of cherries hanging from the branches. There is quite obviously a serious lack of cherries on the branches of these trees. The block is virtually useless now because the infestation has grown so large.

scale 2

Now I am not trying to glorify my position as a scout but there is some importance to my job here. This kind of loss to the grower is quite substantial when you consider having to replace all of these trees because they simply do not produce anymore. This infestation is likely a few years old. If somebody had been there looking for bugs in this block once a week then this possibly could have been avoided.


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