How to bring a neglected citrus tree back

[Orkine]

I had several citrus trees and ended up losing some of them over the years.  I am left with 3 trees that have survived just about everything from hurricane and mild freeze (a couple of hors at least twice in their lifetime of about 10 years) to sheer neglect (little or no fertilizer or pesticide); I wasn't going for organic, just expected they would be affected by citrus greening or some disease and have to be removed.  Well, they haven't.  They are not special varieties, just whatever I got from homedepot and planted at the time.

I am motivated to rejuvenate these tress and wondered if there was a care regime, nutrition watering pruning etc. for citrus that I should use as a guide.  My decision came after a visit from IFAS researcher who was sampling for bugs in the neighborhood and informed me they were healthy, just poorly cared for.  Needed some fertilizer and pruning to remove deadwood and some bad branches growing straight up.  They make fruits now but I believe will make more and better fruit with a little TLC.

I will appreciate any input.

My best guess on the varieties in case it matters, Hamlin, Navel and HoneyBell.

Thanks.

[pagnr]

For severely neglected trees, nearly any fertiliser should get a response.
I would probably first go for a low to medium N, organic based, to give some soil microbe stimulation. Or at least include some soil stimulation.
As for pruning, you may as well remove any damaged growth etc, rather than resurrect the tree with it still there.
For plants with previous heavy leaf loss, maybe prune back the top third, especially naked twigs, rather than trying to get every bud to flush.
Sometimes heavy flushing on tired plants leads to growth stagnation.

[Galatians522]

Essentially Greening is a "plugging disease." The bacteria cloggs the flow of sap and the exchange of nutrients between the roots and leaves. Here are some things to try.

1). Frequent light watering "half as long twice as often."
2). Apply compost (this helps support root systems compromised by greening by keeping nutrients and water close by)
3). Foliar feeding (trees compromised by greening have difficulty getting nutrients from the roots to the leaves so this helps by feeding the canopy directly)
4). Don't neglect minor nutrients
5). Resist the temptation to trim major portions of the tree unless the branches are actually dead. Greening affected trees have difficulty regenerating foliage.

[Orkine]

Thanks.

Galatians:  I understand these trees are clean and not infected.  I had assumed they would be when I lost a few trees in the yard around the time there was news on disease pressure in my area.  That was why I gave up on the trees.

A recent visit from a IFAS citrus research scientist (taking insect samples with traps in my area) led to a discussion about the trees and he explained to me that they were showing signs of neglects not greening.  They fruit every year without much care, two fruit heavily and the third alternates.  The fruits are not clean (not like what you see in stores) and have some scabs  but they are super delicious.

I am hoping to get them to continue to make good fruit but have clean fruit and do so in peak conditions.

So I am reading up on fertilizer regimes, timing and quantity, as well as insect management. 

I have a nice mango collection, and I am learning that mango care is different from citrus care.

[Galatians522]

Thanks.

Galatians:  I understand these trees are clean and not infected.  I had assumed they would be when I lost a few trees in the yard around the time there was news on disease pressure in my area.  That was why I gave up on the trees.

A recent visit from a IFAS citrus research scientist (taking insect samples with traps in my area) led to a discussion about the trees and he explained to me that they were showing signs of neglects not greening.  They fruit every year without much care, two fruit heavily and the third alternates.  The fruits are not clean (not like what you see in stores) and have some scabs  but they are super delicious.

I am hoping to get them to continue to make good fruit but have clean fruit and do so in peak conditions.

So I am reading up on fertilizer regimes, timing and quantity, as well as insect management. 

I have a nice mango collection, and I am learning that mango care is different from citrus care.

I see. All of my recomendations will make the trees healthier even if they do not have greening. However, I would not be surprised if they tested positive (even if they are not exhibiting major symptoms). Last I knew the infection rate around here was close to 98% with most of the remaining 2% being young resets that had not been in the field long enough to develop the disease. If your main goal is cleaner fruit, copper and sulfur sprays will help and you would likely have those products on hand for the mangos. Wetable sulfur is good for rust mites (which cause some of the most noticable damage to the peel) and copper helps with fungal diseases of the peel and citrus canker. Both are commonly used in commercial groves. Below is a link with info about using wetable sulfur for rust mite control.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www2.ipm.ucanr.edu/agriculture/citrus/Citrus-Rust-Mite-Silver-Mite/&ved=2ahUKEwiXu5b9lv30AhXKRzABHUfhC6UQFnoECAQQAQ&usg=AOvVaw0F4m1CUMUPlFgo1aqRyHgz