How much water and fertilizer(s) are you providing? Sounds like an abundance of both??

looks like you are battling some pretty typical powdery mildew, scab, anthracnose we get here in South Florida on carribean varieties. do you witness any pests like spider mites? the tree as a whole looks pretty healthy, not sure why its so stubborn to fruit, NDM is supposed to be pretty resilient to anthracnose. do you recall where you purchased it?

how often do you water the tree? i can see the water spots on that mango, is this a really dewy spot in your yard where the leaves and panicles get in contact with alot of moisture and not much of a breeze? maybe some selective pruning of the inside growth will help with a little circulation

I think I can understand now why Pine Island stopped selling Cushman and Julie, some areas really get hit hard with the fungus

You have a bad case of Powdery Mildew! You can see it on the bloom, and then look at the young new leaves.

If you live in Florida, the first spray I do in late December is sulfur. It is now to warm to spray it.

Try some copper now but watch the PH of the water.

Goog luck, Joe.

pj1881: a little sprinkler water and no fertilizer. Only horse manure as mulch.

Mangokush: I hadn't thought about scab, but I did wonder about spider mites. How do I find them and treat them? Just the outer edges of the tree are watered by my sprinkler. I thought it wasn't hitting the tree at all because I fixed the sprinklers last year to go up to, but not hit the tree. Well, I guess the tree has grown and is getting hit on that one side where the big fruit is. Only the very outer 6" of branch are getting hit right now. I know I need to get out there and work on the sprinklers again, but I didn't even know they were hitting until I started really examining the tree to take these pictures. My sprinklers run twice a week for 24 minutes. That's all its getting by way of water. I was wondering if putting manure on the tree while it's got young fruit would make them split. I may have done that. I'll hold off on all manure for now, and fertilizer I guess. I think I bought the tree at Home Depot and I think it had a Pine Island tag on it, but that was 5 years ago, so not sure.

MangoDoc: wow, didn't think I'd actually get a mango doc with my post, but that's good! I haven't ever used sulfur because I like to use oil for insects and they can be a really bad combo. I think you are supposed to wait a month between sulfur and oil sprays. I'm trying to stay as close to organic as possible. I'll give the sulfur a shot next winter for sure, and I hadn't thought about checking the PH of my water.

Terri:

Well there is no doubt about you tree having powdery mildew. But that is usually only an issue for fruit set and not a problem, in my experience, with fruit that has already set and achieved some size. Mangoes in Florida almost all have thrips and spider mites as well. Oil sprays can help to control them, but complete eradication is very, very difficult. Most mango trees can do quite alright even with thrips and spider mites....to a point. You need to stay away from the manure. It is way to high in Nitrogen for mangoes and especially those given to splitting like Nam Doc Mai. Consider a fertilizer with no or almost no Nitrogen (the first number in the fertilizer formulation) and an especially large third number in the formulation. Are your sprinklers on city water or well water? Those burnt brown leaves look like some type of chemical burn.....and look very much like the burns that I saw on the Zebda mango that was given to me. The tree will out grow that and overall, your tree should be fine. Sulphur spraying will help the powdery mildew and add to fruit set....but Nam Doc appears to be willing to set fruit right through the infestation of powdery mildew.

Harry

Thank you Harry, I was hoping you would see my post. Could I use manure after all fruit have been harvested (wow, that's optimism, I should say after all fruit have fallen off the tree!), or should I not use it at all? I haven't gotten around to buying that 0-0-51 fertilizer yet, but it's on my list of things to do. I probably burned the tree a little last year with my last application of fertilizer. It was 8-10-10 and I used it half strength in September. It has only received horse manure since then. I have a 2-10-10 now. Would that be ok to use or should I wait until I get the other fertilizer? How would you treat this tree if it were in your yard? Spray? with what and how often? Fertilize? I'm planning on another copper spray today. It's been 10 days since the last one. Is that right? Do you have a spray/fertilizer schedule that you regularly follow? Your trees always look so good. Oh, I'm on well water. Have you ever seen tip branches curl like that? When it's blooming, sometimes the panicle will curl too.
Thanks, Terri

Terri, that is a GREAT looking tree...nicely shaped! I'm sorry for the problems you're having and hope you get the tree back to a healthy path.

I do agree that I wouldn't use horse manure for fertilizing your mango tree. Just out of curiosity are you letting the horse manure "sit" (compost) for several months? I've heard that "fresh" or not fully composted horse manure can really burn the roots/trees if not fully composted...but I've never had personal experience with it...just what I've read from people using it.

Good luck and hope you get to taste some of the fruits.