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Peach Leaf Curl in Central Valley, CA

Posted by cebury 9, CA (My Page) on
Thu, Jan 28, 10 at 4:03

How critical is it to heavily spray peach/nectarines to prevent peach leaf curl in the central valley in CA (like Fresno)? We only get about 6-7 inches of rain total from Nov thru Feb, the majority coming on relatively few days during storm weather.

I have several young stone fruits in the ground which haven't fruited (I took them off the first two years) but leafed OK and had no pests. I recently purchased a couple dozen more dwarf stone & pome fruits (genetic and rootstock dwarf) for containers -- none were sprayed by the nursery.

I've generously sprayed Liqui-Cop (8%) per the label on the peaches & nectarines with most showing full swell on buds, but no green tips breaking through. I have not sprayed any cherry or pome (a few apples and a few pears).

I help neighbors with their peach trees and they do not spray whatsoever and have very mild pest problems with no visible leaf curl. They have bountiful crops, too many if not thinned.

1st: Is this because the risk of leaf curl here is much, much lower than in the wet climates of the nation?

2nd: Should I spray my new (bare root) dwarf cherry and pome trees?

3rd: I recently purchased Micro-Cop 50% (took forever to find the last remaining stock) -- should I apply it once 10 days have passed from the original Liqui-Cop application? Or am I fairly safe with just the one before-bloom application on these immature fruit trees?

Follow-Up Postings:

RE: Peach Leaf Curl in Central Valley, CA

  • Posted by olpea zone 6 KS (My Page) on
    Thu, Jan 28, 10 at 13:07


1. You're correct. Fungus don't like to live in a desert. Neither do insects.

2. If I had neighbors growing bountiful fruit crops with no-spray, I wouldn't be spraying anything.

3. Whatever the copper formulation, the purpose of spraying it near bloom on pome trees is for fireblight suppression. The purpose of applying it post dormant on stone fruit is for bacterial spot. With 7" annual rainfall, you don't have either of these diseases.

Sounds like the only thing you have to worry about applying is water :-)

RE: Peach Leaf Curl in Central Valley, CA

Well, Fresno isn't exactly the desert :)
But I lost a baby Arctic Jay the first year I was growing peaches from peach leaf curl. Some varieties are more susceptible than others. I still get a few leaves coming down with it with only one or two sprays, so I would advise try spraying just once, and see if that is enough control. But with some people forecasting monster rainfall in February for California, this isn't the year to be experimenting, IMO.
Carla in Sac

RE: Peach Leaf Curl in Central Valley, CA

I usually update threads just for future reference from folks searching for answers. This year was a strange spring with early heat, then frequent cold and short rain spells.

The neighbors that never spray copper all have peach leaf curl. My trees had zero curl, I only sprayed Liqui-cop once in late Jan as stated above.

IMO, if you live in this area (< 10" rain/yr) you are pretty safe only spraying once rather than twice, for trees that haven't suffered PLC the previous year.

RE: Peach Leaf Curl in Central Valley, CA

We have actually had a horrible peach leaf curl season here in Northern California due to our weird cold spring. It's only been since it got warmer towards the end of May that it has stopped. For example my Spice-Zee nectaplum has had almost every leaf affected ongoingly, even on growth now a foot or two long, on every leaf that has come out since February. Usually its just the first flush of growth, and it's over. I haven't sprayed again because I keep thinking it's got to stop sometime!!!

Do those of you in rainy climates spray all year for curl?

Carla in Sac

RE: Peach Leaf Curl in Central Valley, CA

Carla, peach curl infection doesn't take place year 'round, it only takes place once when the buds swell. Basically, asexual spores get washed into the buds and there they infect all the future leaves to come out. That's why spraying is totally ineffective once you discover you have peach curl.

So usually it's sufficient to spray your favorite fungicide (organic or synthetic) right at bud swell in the Spring. However, to be safe, it's best to spray once in the Fall right after leaf fall as well to reduce the spores going into Winter.

In a warm year, peach curl may already be in the leaves but if conditions are warm and dry, then the peach curl fungus can't grow. It likes it best between 50 and 70F with plenty of rain.

RE: Peach Leaf Curl in Central Valley, CA

Yes, well, that's what I thought, excdept that I have foot-long branches of new growth, which started growing in February that have peach-leaf curl along the entire thing! I do not understand how every new leaf has curl on it, now for 4 months.

Carla in Sac

RE: Peach Leaf Curl in Central Valley, CA

I've seen the same behavior Carla -- new leaves will still spring up here and there, I assume if the weather and ferts support it. When they do, they already will be carrying the fungus if the other leaves had/still have it.

Oh and BTW -- my young Bartlett pears are also showing signs of Fireblight damage at the tips of several limbs.

Olpea said: With 7" annual rainfall, you don't have either of these diseases.
Perhaps "in any severe form" should be added to the end of that sentence.

Carla, do you spray anything other than Copper/Sulfur and a dormant oil for your fruit trees? And of course, the Tanglefoot.

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