This is from Australia, but perhaps it's the same here. http://www.daff.qld.gov.au/plants/fruit-and-vegetables/fruit-and-nuts/custard-apples/faqs-about-custard-apples/faqs-about-pests-and-diseases-of-custard-apples Edit: Think I should pay better attention! Here is a link that might be useful: black custard apple This post was edited by jean001a on Sat, Mar 29, 14 at 22:29

Keepitlow, I'm not sure they're increasing on a global scale, it's just that societies are much more mobile now, and bring pests along with them, so that there is a larger diversity of pests here. A couple more imported pests that come to mind are Japanese beetles introduced in the early 1900s, and the very recently introduced spotted wing drosophila fly. Once introduced, it has generally taken a long time for some of these pests to become omnipresent. Codling moth, even though introduced with the first settlers, didn't find it's way to Kansas until 1850. Japanese beetles, even though introduced 90 years ago, are still not found in all KS counties today. However, in the future with our society even more mobile, it may take less time for these newly introduced pests to fully disseminate. OFM has become more of a problem due to mutation. Originally it was exclusively a stone fruit pest. In recent years it has become a pest in commercial apple orchards as well. I've also read it can be a problem in some home orchards where there are lots of stone fruit and apples planted together. To the naked eye, the larva are indistinguishable from CM. Lastly, introduced pests are not limited to fruit. Bedbugs have been practically unheard of here for half a century. Remember the old adage, "sleep tight and don't let the bedbugs bite"? That came from a time when people slept on hanging rope beds. Bedbugs could be somewhat thwarted by tightening up the ropes to prevent the bed from touching the floor. In recent times some hotels (even nice ones) have had problems with bedbugs being reintroduced from overseas travelers. That'd be a case where I'm going to kill some nature, and feel really good about it.

If the black death doesn't consume the rest of it and it maintains adequate vigor eventually the tree will replace the missing portions. First question is what the blackening was, maybe local Extension office can help. They will need samples.

If you are in one of these regions with extreme heat that is also probably contributing. Bottom line, though, it looks bad, but it is largely cosmetic damage. I've planted many trees that look like that during their first season or so if it's hot and dry and I haven't watered enough. They bounce right back, either when wetter, cooler weather returns, or the next year.