My Mother passed away recently, and her memorial services will be in 2 days. I need advice as to the longest lasting fruiting tree for her zone (8A) which will be planted in her memory with her ashes as part of the soil, so this is an important decision... It will be her permenent resting place. I do not want anything that will die in the next 20 years, and it does not need to be flashy... but it needs to bear fruit. PLEASE HELP! and THANKS!
My sympathy on your mother's passing. Planting a tree is a really nice tribute. There are a number of factors you need to consider. Will someone be taking care of the tree? How much time can they devote to taking care of the tree? Soil type? Do you want a low or high maintenance tree? You may want to contact your local Cooperative Extension agent to get a list of recommended varieties.
The oldest living fruit tree is called the Endicott Pear located in Massachusetts. It is over 350 years old. Around old homesteads in this area, you'll find some very old pear and apple trees.
They are both high maintenance trees. This means they will need to be pruned, sprayed for pests, fruit thinned. There are a number of pests and diseases that can shorten their life. Aesthetically, the apple tree is the nicer looking of the two.
If you are looking for a low maintenance long lived fruit tree, the Japanese aka Asian persimmon tree is one to consider. In China, there are a number of 500 year old persimmon trees that are still bearing. One advantage is that they are smaller than both the apple and the pear trees and can be kept that way. They are very healthy and normally pest free trees. They bloom late so they bear fruit every year. This is important in areas subject to late freezes. There are 2 types of Japanese persimmon trees: astringent and non-astringent. The astringent persimmon fruit has to be soft ripe, almost like jelly, before you can eat them. The fruit is sweeter then the non-astringent persimmons. However, the non-astringent varieties can be eaten as soon as they ripen ans are eaten much like an apple. Hachiya is the most common astringent persimmon sold. Fuyu is the most popular non-astringent persimmon sold.
Chilling hours need to be considered as well. Apples need a number of hours below a certain temperature. Different varieties have different requirements and there are quite a few apples that will not grow in the south. (along with needing regular maintenance) Checking with your Extension Service is always a good idea, here is the website for Louisiana: http://www.lsuagcenter.com/ although you might need to check for whatever state the service is to be held in. Each county has an office and knowledgeable staff to help make gardening decisions.
You might consider something like a pecan as well. Many of them live to great ages.
Sandhill plum, aka Chickasaw plum is a thicket forming plum. The dirt/gravel road leading to our ranch is lined on both sides with it. Over time it has gotten 5' - 6' wide along the fenceline. The county has to shred it several times a year to keep it from taking over the road. It's one of those trees that are nice to see, but in someone else's property.