I would think that heat certainly could kill a tree or any other plant fot that matter. Maybe shading the root area with either mulch or ground cover would help for extremes. Root system of citrus trees are not very deep and when it is hot like this I would water more often as this wouls also help to keep the roots cooler. Although a big portion of the tree died, it might come back?

Try and search Google for ~ sudden death lemon ~ . I was surprised. I never heard of such. Seems it is a real problem.

ETA Seems to be a problem in Australia, Brazil, and Florida so it probably should not surprise you in Arizona.

I agree with mole. It may come back to a reasonable degree.

6b Steve

I live in Ventura county in Southern California and had 118 degree heat for 3 days with unusually high temp for 2 weeks this past September. Then had freezing temps in November. Top of Meyer lemon tree has yellow leaves (about 25% or more of tree). Only have about 200 lemons and last year had over 2000. Should I wait to prune back the yellow branches until the spring to help protect tree from further frost damage? Should I fertilize with nitrogen? I have never fertilized before (tree is about 15 years old and in the ground. Any ideas and suggestions are appreciated to save me once prolific tree.

Judicious pruning would help; we all feel better when we know we look good.

The Fresno Ag. Dept. recommends fertilizing citrus in Late February, Late March, and April; how much depends on your soil and area. I use a liquid these 3 times, plus I scratch-in a long release fertilizer sometime in the Spring. You could get the right amounts for your area from your County's Ag. Extension Service.

Also, fruit trees tend to have a great year and then take a rest the next. This year might have been your tree's "off-year".

Kate

Thank you so very much! Great info and advice. And I feel much better. There will be less limoncello made this year, but looking forward to another bumper crop in 2021.

There should never be a hurry to prune wood damaged by weather conditions. Everything considered, leaving the tree alone is the best plan. For some time following injury, it is impossible to determine how much pruning should be undertaken . Much expense and labor may be prevented by waiting until the exact extent of injury can be determined. This cannot be decided until new growth starts.

Thank you. Definitely will wait to see how it makes it through until spring. Funny how each year the fruit shape, size and attractiveness is different. Last year fruit was ugly, but otherwise plentiful and delicious. This year beautiful lemons, but so few. Picked these yesterday. Enough to make a couple batches of limoncello and curd

They look beautiful!