Why are the leaves of my peach trees turning yellow?

Question

With the help of the internet I think I've narrowed down a yellow leaf problem on some peach trees to a couple various causes. However, after comparing pictures - they look different. Back to the drawing board, trying to figure out where I went wrong.

Here's some other information that may be helpful.

• New trees, planted just this year. (My first time gardening actually)

• Trees received from someone who knows the importance of organics. Transplanted when they were about 3" tall.

• Up until this point, trees have been doing fairly well (aside from pests). The tallest being about 26" (although it's the closest to a field, so I'm assuming it had something to do with fertilizer run-off.

• Average tree height is around 12"

• Trees are planted about 5ft from a ditch line. It rains a couple times a month but I wouldn't think enough to be over-watering them. The ditch is hardly ever saturated except on the day it rains.

• Had issues with various pests eating my plants so I spray (a couple times a month) Garden Safe Organic insecticidal soap.

• Family members own a couple bunnies so instead of "wasting" their droppings (See what I did there? :) I put a large amount [big heavy garbage bag full] into a barrel, add water, let sit for several weeks and take 2 cups off for 1 gallon of water.

• Water them every night in the evening with 2 gallons of water total for 8 plants. About 1/4th gallon per plant.

• About two month ago, I put some rabbit pellets (plus mulch from cage) at base of plant. It's still there although quite dried out and lost most of the coloring.

• First noticed something wrong about two months ago, where one tree in particular had what I thought might of been nutrient burning. The edges of the leaf were a rust looking color. I sparsely resumed using the fertilizer but not as much. [Picture #1]

• After a month, the leaves were still yellowing. I immediately stopped using the bunny fertilizer. [Picture #2]

• After about a month without, a yellow tint around outside of leaves appeared. The rest of the trees finally caught up. Resumed fertilizer yesterday in hopes of fixing because the plants are still moving toward a yellow-droopey state. [Picture #3] (Beware this picture's lighting is over-exposed)

• The largest of the trees is still fairly green but is finally starting to yellow on some leaves. This is the color the other plants should be. [Picture #4]

Potential causes:

• Over watering
• Nutrient deficiency
• Nutrient burning (from manure; even though I stopped for over a month with no change)
• Very hot and humid days (this summer got into high nineties (95%F+ at 80%+ humidity)

Picture time:

1 - Potential nutrient burning

2 - First sign of yellowing

3 - Over-exposed picture of yellowing

4 - Largest tree, finally yellowing

Answer 1

I'm not 100% sure there's no other problem, but your watering regime is insufficient - young woody plants require probably around 5-8 gallons of water a week each if the weather is hot and dry. It's also best to water more copiously and less often - giving a little every day encourages surface rooting, that is, the plant is learning that water arrives daily, but in order to access it, it needs to put roots towards the surface, when what you want to encourage is deep rooting rather than it rooting in such a way its waiting for you to come along with a couple of pints on a daily basis.

New trees also do better if the soil around them,to a distance of 12/18 inches all round, is bare of plant growth, including grass, preferably with mulch of organic origin on the bare soil (though not right up against the stem or trunk), otherwise there's competition for nutrients and water between them.

Whether there are other troubles is hard to say at this stage - the symptoms you describe can easily be accounted for by poor watering technique.

UPDATE

Further to your comment, I apologise, I didn't mean to sound reproving, if that's how it seemed; if it's any comfort, watering is the thing people most often get wrong. I'm not sure where you are, but if it's somewhere you get winter, then likely Fall approaches, so don't fertilize any more this year. Note also its never a good idea to give fertilizer to plants which look sick - if the cause isn't shortage of nutrients, the plant can't take the fertilizer up and it may cause additional problems. Diagnosis first, treatment after!