Peach leaf curl - alternatives to copper spray?

I have 3 peach trees and I live in N. California zone 9b. We get peach leaf curl very bad.  It's been recommended I spray copper on them 3 different times a year.  I am trying hard not to spray toxic stuff in my space.  I think since copper is a natural substance it should be alright, but I'm not sure what else is added to the store bought copper.  So I thought I would ask what you all recommend, and or do?   Is there anything better or different?  

I think they copper fungicides are typically copper sulfate but I might be mistaken. I tend to lean towards it being an alright foliar spray but would worry about continual use causing harm to the positive fungal friends, especially if it is getting into the soil.  I would think regular sprays of quality Compost tea from before budding through the season could help, there are probably also biofungicides available but they are likely pretty spendy. My instinct would be to try compost tea sprayed until I saw some sign of curl and resort to copper if I saw a sign of serious infection.

Compost tea didn't work for me, unfortunately, on the one tree I have that gets it badly. My best advice is to plant cultivars that are naturally resistant to curl. They will get some if left untreated, but the leaves just fall off. Frost and Salish Summer Peach have been best in my experience. Oregon Curl Free sounds promising, and I hear good things about Namaimo. Peach trees are not very long lived, so I would plant new ones every few years. For your current trees that are in the ground, you might try grafting over them.

Sounds like peach seeds might be a great option for us in the northwest

Also I recalled that silica can be used as a foliar to aid in fungal resistance and I've seen pretty crazy general immune improvement from using sea-crop fairly sporadically (I'd imagine other sea mineral concentrates would be similar, I'm just partial to sea crop and it's kinda local coming from Olympia I think )

s. lowe wrote:Sounds like peach seeds might be a great option for us in the northwest

Also I recalled that silica can be used as a foliar to aid in fungal resistance and I've seen pretty crazy general immune improvement from using sea-crop fairly sporadically (I'd imagine other sea mineral concentrates would be similar, I'm just partial to sea crop and it's kinda local coming from Olympia I think )

I'm trying to grow some seedlings from curl resistant varieties. They're in pots outside now and hopefully will sprout in the spring. I'll keep everyone updated

I'm only planting resistant varieties now. I grow lots of seeds every year and plant a bunch out. If they get stricken with leaf curl, I pull them out. The strong survive. We have a few heritage varieties that are more or less impervious, so they are well represented on the property ;-)

In one of his tapes, Bill mentioned knowing a friend who used to drive a copper nail into the tree-- he was somewhat vague on length of the nail and whether he used more than one per tree. and recent searches on the internet turn up mythbuster type articles for this type of treatment.

I could not find any hard scientific research, but lots of scientific projections of why this approach was "nonsense" and just an old wives tale, but that alone does not add up to full proof using the scientific method, just empty handed "experts offering opinions/ hypotheses/ guesses--

I did see one article that said the only way to kill a tree with copper nails was to get so many nails the tree was buried underneath them, so with no great harm likely, I will  start to play with them in my garden next year.

I think the idea of foliar kelp spray or compost tea is likely a better short  term solution--- healthy plants don't get sick in the first place, so good nutrition in the soil is probably the best way to go long term.

The chemical treatments must vary according to which expert or producer you talk to, i've heard of the sulfate spray also, and one search turned up a chloride compound as the best treatment (I'd rather let the tree die before using it, sounds extremely toxic to fungal soil organisms which trees depend on, which would lead to a circular sort of feedback- weak trees, sprayed with stuff that also kills mycorrhizae, further weakening trees, requiring even more spray.

If you do spray out of desperation make  sure to follow up with fresh soil inoculations of beneficial organisms (compost or compost tea- AACT)

I did see one article mentioning that leaf curl tends to disappear later in the season anyway, so whatever you try may have more to do with years rather than weeks or months of observations

We have had peach trees for years, and usually don't spray them, because I forget to be honest.  They always get peach leaf curl very bad.  The leave do fall off and new ones do emerge, but I thought this was bad for the tree in the long run.  I have never done anything for the tree on the ground.  I'm going to make this a priority this year.  We have one old peach tree that I thought was on its last leg.  Last year I put wood chips between the peach and a very old walnut, which I thought was dead.  Both trees look better than they have in years.  The chips weren't even spread around, that is just where the ones I didn't use ended up.  I did notice this, but  don't think I realized until this discussion that the old peach did have leaf curl, but not nearly as bad as the others.  Mostly I was thinking the wood kept the water that we actually got this spring available to the tree, but now I realize it is so much more.  
I have intended to put wood chips around all of the fruit trees, but it keeps getting shuffled to the back of the to-do list. I better move it to the front of the line.  Maybe if I can get these trees very healthy I won't have to spray, or at least spray less.  Thanks for the revaluation.

Walnut trees will compete with the other fruit trees and put out chemicals that will weaken them. Part of that competition involves the fact that they (walnut trees) tend to thrive in and create a less fungal soil than other fruit trees, and actually don't mind the competition of grasses, which are quite bad for most fruit trees.  The wood chips enhance the fungal properties of the soil (and kill grasses) which helps the peach tree.

@Bob Day - interesting comments about the kelp spray, I am seeing conflicting information.  

Does anyone else use Kelp Spray?  According to sfgate: https://homeguides.sfgate.com/fruit-tree-spray-peach-leaf-curl-59851.html - "Kelp sprays have been shown to worsen infection in some cases." However, here is the recommendation: https://www.santacruzsentinel.com/2019/04/25/this-week-in-the-garden-restore-health-to-plants-after-wet-winter/

I don't know what to believe, but my necataplum tree (Planted 1 year ago in heavy clay soil (San Diego) has A LOT of leaf curl and the fruit are about the size of a dime so I'd imagine it's too late to use copper on the tree until next year.

My brother-in-law was a nursery man, and he said you have to spray 3 times.  I always forget, and our peaches always have peach leaf curl.  I think you're supposed to spray around early winter, beginning of January, and again just before the tree buds.  I could be off on the times, I never seem to manage them, which was one of the reasons for the post.  I do know if the tree already has it it's to late.  Most of the time it will recover on its own, and still produce.  It just looks sad for a while.  Good luck to you.

I have heard that kelp foliar spray on corn helps corn produce it's own  defense against some pest (corn worm maybe?) , so it seemed reasonable that it might be useful with peaches as well, but I have no experience yet, so thanks for the heads up about the conflicting findings on whether it works or not.

We had a dry winter so maybe this will be a better year