Dryland fruit trees

Maybe five years ago I started working on acclimating my fruit trees to not being watered. The almond and grapes have thrived. The plums gave us a decent crop last year, not great, but this spring they have very little new growth. I'm assuming it's because the winter has been exceptionally dry. We got our first snow last week, maybe two inches.

There's no way to water during the winter, and I've never considered that a necessity before. All the seedlings seem to be doing fine. The grapes and almond look great, as well as the walnut. Even the grafted apple is putting out new growth.

It's just the plums. They still appear alive and the leaf buds look normal. Both trees are mature and have been in place upwards of 10 years. The older of the two is at least 40 years old. They have never been fertilized and only minimal trimming.

Are there other things that could result in not having any new growth? Has anyone else seen this? Or is this another of those questions where I find out the answer two minutes after I hit submit?

I don’t know your zone; but trees have a dormancy period.  It’s generally not necessary to water during dormancy. The tree is not active. That would be winter.

That being said; deep watering in fall preparatory to winter is recommended for trees and shrubs.  

If your tree is leafing out...it’s out of dormancy and now requires moisture.  

Fruit trees generally produce fruit on new wood.  So if you are not pruning and not watering I would guess both are a problem. A 40 year old tree will have mostly old hard wood if it has not been pruned back.  I would not expect much fruit.  A 10 year old tree could also have mostly hard wood.  No fruit on hard wood.

I don’t know about nut trees..I don’t have any..but juicy fruit like plums, peaches and apricots require water.  I don’t think you can “ train” a juicy fruit tree to go without water.  Some varieties may do better than others with less but I think the quality of the fruit will suffer.

Assuming your trees are healthy and have good pollinators if needed; pruning and water are necessary if you want quality and quantity fruit.

I'm not really concerned about the fruit piece at this point, but about the general health of the trees. The trees are in full dormancy but the buds look normal for this time of year. Last year I didn't water the almond at all and got a good crop. The other trees got water once during the summer. The prior year all the trees had normal crops with only once a month deep watering, and actually seemed happier for it. The almond doesn't seem to care about the difference in water. The walnut had a smaller crop, but the nuts are full. Up until this spring the plums have also behaved normally. I was expecting the smaller crops, but I was not expecting that the actual patterns of the trees might change.

All the trees are treated the same (minimal pruning) and until this year have behaved exactly as expected.

I think (?) that the problem might not be the water itself, but the prolonged drought. We didn't get our spring rains last year, didn't get our fall rains, didn't get the fall rains the PREVIOUS year, and very little snow this winter. This is part of why I am training the old trees, and planting the new trees in a way that they have deep roots and don't need as much water.

All the trees behaved normally until this year. I wonder if the water bank is depleted? I hadn't thought of that until I saw the trees the other day. Even the walnut is putting out new growth--only the plums are behaving differently. The seedling apples have new growth, seedling apricots, seedling peaches. Even the plants that are extremely water hungry are showing normal growth. Only the plums are different.