random leaf drop in orchard

[redster]

so in april I started caring for a small little orchard of various citrus trees a few miles from my home. they had never been cared for, AT ALL.  it looked to me they started with 55 trees and after 4 years were left with only 30 or so of various growth, rootstocks, and other maladies.  one lime had citrus canker...

i pruned rootstock, sprayed and poisoned, basically everything but fertilized. that wasn't my call to make, i expressed my disapproval, but lost in the end.  everything seemed fine till about 2 months ago.  about 10 or so random trees, started dropping leaves, and showing some signs of dieback.  at first i thought it maybe be anything, drought, too much rain, nutrient issues, who knows... but now as of today, some of the trees are putting out new growth...could this have been really late and delayed winter damage from the 3 hard freezes Louisiana saw last winter??? where do i go from here, assuming a milder winter than last year, ill prune what survives in spring, but should i fertilize or do anything else till i know for certain what this could be??? im still mostly at a loss, as winter damage is new to me down here.

thanks

 red

[Luisport]

They look dry...

[redster]

that was my first thought, summer was fairly dry I guess,  but im just not sure.  its like every other or every third tree, different species, it really seems too random to me to be drought...of course the same could be said of any other maladies, so who knows.   if it is, I don't have much way to get irrigation to the trees, these guys weren't too smart 4 years ago when they planted them. but after 4 years even trees that hadn't grown much should have enough roots to find water.  the water table around here isn't very deep.

but to answer my main original question, how long should it take to show freeze damage to limbs of a tree?

[Millet]

The tree does look quite dry.  One of the first things you can do is remove the vegetation from under the tree, as the vegetation drinks a lot of the water that would otherwise go to the tree.   Spray it with Round-Up.  The leaves also look very yellow under nourished. How often do you fertilize?  A tree should show freeze damage in just a few day after a freeze event.  -Millet

[redster]

yes we working on the grass problems. they were considering mulch, but im hoping it don't happen.  in 4 years they've never been fertilized.  but looking at the upside down orchard pic, some trees are doing fairly well considering that fact.  certainly not as well as mine at home that have been well fertilized, but they surviving...I cant believe the soil is that different in so many places to allow drought and nutrient problems...maybe I need to start digging, see whats going on under there.

[Millet]

redster, the trees in the top two pictures of your post look to be especially deficient in nitrogen.  In cases of
severe nitrogen deficiency, leaves drop and foliage becomes sparse. N deficiencies often occur in winter
or early spring because of low N reserves in the tree, low soil temperatures which reduce N mineralization rates, and lack of
root activity due to the lower temperatures.  As to digging, you must be very careful digging into the root zone areas of an in ground citrus tree, considerable root damage is quite possible.  Ninety percent of a citrus tree's root system is located in just the top 21 inches of soil. - Millet