"See if you can find any information about P that is actually based on research in the field where a lack of it has caused production problems. Check into Australian fruit production because, as I recall, their soil is ancient and very low in P." I Googled for a little bit and really didn't come up w/ much scientific info. (At least they didn't explain any science behind it.) I quickly came across a few examples like this: http://archive.agric.wa.gov.au/objtwr/imported_assets/content/pw/gard/nutritional_gn_formatted.pdf where they have a quick blurb about P, where they say, "Phosphorus is essential for the development of flowers, fruit and roots....In fruit trees, flowering and fruiting may be affected. Deficiency symptoms are more prevalent during cold, wet conditions. To correct the deficiency apply solid or liquid phosphate fertilisers." Ive read lots of stuff like this in the past, but I know you are looking for something more substantial. In Prof. D. Layne's book "The Peach, Botany Production and Uses", he mentions that P is rare in peaches and that generally there is no response to adding it. Interestingly he does say that P deficiency can occur, causing reduced growth, without any visual symptoms in the foliage. I'd post the link to the book, but since it's a copyrighted book, the link may not pull up the same pages I was reading. Google books does that sometimes. I know you are somewhat annoyed that commercial guidelines could recommend adding P w/o a soil test, but again it's only for the first two years, it's a small amount, and in a commercial orchard, where that amount of P would probably be used up by the time it got down to the root zone. The U.C. Davis link you posted above get their info. from their nutrition manual (linked at the bottom of their page). The authors of it even state, " In fact, annual requirements of fruit trees in general range from 5 to 10 lb/acre (6 to 11 kg/ha), which is much lower than for many field crops." Although they don't specifically state a maintenance program for P is required, they do imply it. Of course they don't recommend application of nutrients w/o testing, but U of GA only mentioned it for the first two years, which isn't a big issue to me. I've always read that P is very stable and immobile in soil, so I think the risk of pollution from a couple very light applications of P is very minimal. It seems most pollution from P comes from sewage treatment and feed lots. The link from the U.C. Davis nutrition manual says,"However, there is minimal leaching loss of phosphorus from the soil because it exists predominately in these insoluble forms." To me the danger of too much P is the reduced uptake of Zn, which is pretty important to peach trees. But there is little risk of too much P in this area, unless someone was careless w/ applying it. You may be right, that P doesn't matter for fruit trees, but there seems to enough university publications recommending a minimum level for it, that I think it warrants addressing in soils low in P, such as in this locale. Although I agree, there does seem to be a degree of conflicting advice about it. I think Rayrose has a very good point that Ph is just as important as the actual level of P in the soil, in terms of root uptake. I also agree that too much emphasis should not be placed on any one nutrient. I hope I haven't left the impression that P is the only nutrient that matters, or even the main nutrient. I just originally addressed Clark's situation based on my own soils, which showed P the most deficient of all nutrients. But I tried to qualify that by recognizing soils my be different in his part of the state.

The only one I can think of at the moment would be 'Lecont Hican', which is a hybrid between Pecan and Water Hickory (maybe it would get the wet soil tolerance of it's Water Hickory parent). From what I hear the nuts can still be quite bitter though, so I'm not sure if you would actualy want to eat them or not. Overcup Oak would be a great choice if you didn't need something with edible nuts. Here is a link that might be useful: Oikos

I think undernourishment might be the problem. Not too easy to tell from the pics, but I saw what looked like nitrogen deficiency. Do you feed them? Citrus are really heavy feeders, and will produce no/poor harvests without food.

Hi Mike, What else can I explain to you because you seem to understand. I think the concept need's to be taken within reason. Total number of nodes or perhaps total number of contiguous nodes which would amount to a certain vegetative size or mass likely has to be fulfilled too. I think that idea of contiguous branching is the missing element in pushing a juvenile into fruiting. That could explain why some seedling citrus become vegetative giants in a tropical greenhouse without going mature. They have many contiguous nodes from unstressed growth but little contiguous branching from unstressed growth. Start stressing a highly vegetative tropical greehouse juvenile with some repeated droughts and it will often go fruiting. The drought stress kills the tip and new growth will be contiguous branching which seem's to follow a idea of contiguous branching being a factor. All I have ever read on the subject is that abstract which I found in a Google search several years ago. However it made perfect sense and my first trial a contiguous branching pruning seemed to work. I welcome you to buy that article and read it.