Thanks Scott. Do I need to treat it with anything or just watch for now to see if it spreads? I have sprayed it once with a fungicide but I didn't notice any change.

Yes, I was told that some quartzite does etch. I was asking on the stone advise forum about one called Mont Blanc that was listed as quartzite by the stone yard and this is what I was told: Mont Blanc is not a granite. It was introduced as a quartzite which is harder than granite. But unfortunately it is not a quartzite. It is what we have come to refer to as a hybrid marble/quartz material. It will scratch and etch. It is suitable for kitchens as long as you treat it like a marble and install it honed. So although there are probably pure quartzite stones out there, there are also stones that may be somewhere in between. That means it is probably important to test the stone you are getting the make sure it is what you expect. I would be very upset if I got a "quartzite" instead of marble because marble was not practical for me and ended up with soemthing that would stain and etch anyway. Sue

I love it here too, and remember that last year it was in the 90s in April, so I should keep my mouth shut. Didn't do any gardening today, but did take a long walk, so I enjoyed the cooler weather. Pretty soon, my walks will be restricted to very early morning hours due to my lupus, so I'm trying to enjoy this while I can.

You really don't have a problem with using growth fertilizers as we near cooler weather. The tree is deficient in magnesium. Magnesium does not cause new growth flushes that can be damaged by cold weather. You can apply one table spoon of Epsom salts (Magnesium Sulfate) in a gallon of WARM water to the trees root system. You can also apply it as a foliar spray directly to the leaves. It could take more than one root zone treatment. The deficiency that your tree is showing is somewhat common.