Yellow leaves are usually a sign of either a lack of nitrogen OR iron. So, how can you which one your plant is deficient in? Well, it is really quite easy. Monday, we talked about nitrogen deficiency, which causes older leaves to yellow and newer leaves to stay green. However, when it comes to iron deficiency it is the opposite - younger leaves turn yellow first. The other characteristic of iron deficient plants is that although the younger leaves turn yellow, their veins remain green. Iron is needed for plants to function. Without it, they will not grow. What is interesting about iron is that there is usually plenty of it in the soil. BUT, certain factors can affect it being available for plants to absorb. If your soil is wet, has a high pH (alkaline soil), and/or clay soils are all factors that can lead to iron from becoming unavailable for plants. Iron deficiency is best treated by preventing it from occurring in the first place. If your soil pH is over 7.0, clay-like OR often wet - then incorporate compost and peat moss before planting. http://www.birdsandblooms.com/blog/yellow-leaves-and-green-veins-iron-deficiency/ Here is a link that might be useful: Iron Chlorosis

The Burneyville mesonet station often gets 3 to 6 (and occasionally as much as 10) degrees lower than our place does in winter and especially in late spring, and that's really something because our place is in a low-lying creek-hollow in the already low-lying (as you know) Red River Valley. On May 1st, I think we only went to 35 or 36 at our house, but I had all the warm-season crops covered with a frost blanket type floating row cover that gives at least 10 degrees of protection, so I was ready for anything down to 22 degrees. Living in a cold microclimate keeps you on your toes and makes you prepare for the worst when a late cold night is expected. I believe it was in 2008 that our forecast low on a night early in May was 50 degrees so, naturally, I didn't cover up anything. I went outside the next morning to 32 degrees and tomato plants that had been 3' tall and covered with fruit were frozen to the ground, as were pepper plants and even potato plants. I learned a lesson that year, and now I am careful to cover up my plants on any night I think will drop down below about 40 degrees (which wouldn't have helped on that night that we went 18 degrees lower than forecast). Most of the plants resprouted from the roots, and there were 5 or 6 tomato plants (planted on the highest point of land in the garden, right next to the gravel driveway) that only suffered freeze damage but didn't die. I think that being close to the driveway helped them stay warm from some of the heat it absorbed during the daytime. Anyhow, that's an example of how tricky the weather can be here along the Red River, so take all your forecast lows with a grain of salt the first few years until you learn if your specific location tends to have temperatures that are more or less the same as your mesonet station's, or if you're in either a much warmer or much cooler microclimate. We got colder than usual here this year at our house and I expect y'all did too over there near Durant. Some trees that normally are not damaged by the cold not only were damaged, but one is dead and one is clinging to life. Others lost flowers and leaves on one of the many late cold mornings. I almost never lose a tree here to heat or drought, but extraordinary cold gets one every now and then. Often it isn't the cold temperature itself, it is that it arrives either very early in fall when the weather has otherwise remained warm so the trees haven't had a chance to adapt to increasingly colder weather or it happens in spring after everything has warmed up and leafed out and lost its cold tolerance. Hopefully your live oak only lost leaves to a late cold spell and will put out new ones. When we first moved here from Texas, I kept trying to trick Mother Nature and grow some zone 8 plants that I loved. I could get away with it for a year or 2 or 3, but eventually Mother Nature wins and the zone 8 plant dies, so I've stopped trying to do that now. I had damage this spring on Mexican plum (native to our property and this one looks entirely dead), Mimosa (lots of freeze damage but regrowing now....and, yes, I know it is a trash tree but I grow it for the hummingbirds who love it), my 'Jane' magnolia, which has struggled since the tremendous drought of 2011 and just may not make it, and Chinaberry, another trash tree I loved in Texas and planted here for the hummingbirds and butterflies. I also may have lost an in-ground Brown Turkey fig that froze back to the ground but isn't putting out any new growth yet. It should have shown regrowth by now. The Brown Turkey fig in a large container (a black molasses cattle feed tub) spent part of the winter in the greenhouse and part of it outdoors and is fine and fully leafed out. This was a really hard winter for trees here.

This is my experience: not having any live oaks on my property, I collect between a hundred and a hundred and fifty bags of oak leaves from the curbsides of my neighbors every year about this time. Most of them I put on the beds for mulch. I stack about twenty or thirty bags along the back fence out of sight for use throughout the rest of the year because in the beds they decompose into almost nothing by late summer, especially if we get some rain. If the bags don't have a lot of grass clippings in them (I don't pick up those since they are too heavy) they don't produce an odor and are preserved in the bags just as they were when collected. If I stick holes in the bags to let rain in, or the leaves were raked when moist, they start to decompose into sweet smelling compost without producing an odor. I used to have lawn guys that would dump leaves directly into my compost pile, which was constructed of a half circle of wire held away from the chain link fence by rebars pounded into the ground. With nothing added, no greens or anything, they composted down to very little well within a year; or in a few months if it rained. (In the old days when water was inexpensive I would wet them down.) I would just keep pulling the good stuff out from the bottom and just keep adding to the top. I don't know why most everyone couldn't just make a area in an out of the way place to pile the leaves and let nature take its course. Love those oak leaves! :-)

Sorry and thanks, Ken. No pots. They have been in the ground for three years. They were 60 gallon when purchased. We are in Fulshear, Tx 30 miles outside Houston. I'm not aware of any soil problems, but we did recently have a soil test done for our lawn. We have around twelve 75 year old pecans that do well and our other "young" oak seems to be the picture of health and it is planted about 25 feet from the one in question. I don't have a pic right now...Could it just be slower to "darken" with the new Spring growth?