|Granny Smith - store bought & garden grown.|
Since publishing this post, I have found out that the "scab" is called russeting and is caused by humidity as the apple develops. The example in the image above is an excellent example of very low humidity russeting since California is in the midst of an historic drought. Chemical supplements can be applied to have apples of more consistent size with a pleasing appearance. I found this interesting post regarding russeting. UC Davis also has an interesting explanation of russeting on apples. Scroll down to page 4 and read the article regarding russeting. Irrigation after the petals fall and there after seems to be important in avoiding russeting. This is similar to cracking in tomatoes when soil is allowed to dry out then water is applied. The plant sucks up the moisture and as a result, stretch marks are created.
All the fruit trees and berries have been fertilized and given a layer of compost to tuck them in for the winter whenever it arrives. The apples are the only fruit left. Once the leaves start to drop, I'll have a better view of the limbs to enable some pruning before Farmer MacGregor applies the dormant spray. Until then, we're still dreaming about some cold, wet weather.