Is it too late to spray copper to combat peach leaf curl? My guy at the local nursery said to spray while dormant which I did, but now that it’s all leafed out and there are some peaches forming I’m noticing leaf curl.
Is it too late to spray again? Should I remove the infected leaves?
Chris,
Yes,it is too late,after the leaves come out.They can be left on and will naturally fall off,when warm and dry weather comes.Then they should be collected and disposed of.New leaves should take their place. Brady
Thanks. Any idea why they still got infected? Did I spray wrong or is some leaf curl normal?
Your timing or material might have been less than optimum. If bad in your area you probably need to spray at least twice, late fall and before buds start to swell.
Last year I used copper at dormant at 2 places that annually suffer serious PLC set back. A single spring ap of copper didn’t eliminate it completely, but infection was so minor it didn’t matter so I treated the trees the same way this season. Too early here to evaluate results.
You might want to hit the leaves with a foliar N to aid in their regrowth.
Don’t bother removing the damaged leaves, in fact the tree might be able to use them for photosynthesis. The curling is the symptom, the activity has past.
My understanding from plant pathologists is that there is no purpose to collecting and disposing of the leaves as they do not harbor the infection.
Also, in my area if the peach leaf curl symptoms appear on 5% or less of the leaves we’re doing great!
I’m pretty sure the infection is spread by spores forming on the leaves. I have gotten curl a few times and I learned to check every few days and immediately remove any curled leaves before spores could form. The next year there would be zero curl.
I have also read that experts don’t think it helps to remove leaves, but I expect they did not go after them with the vigor you need to if you want to get all the spores out. It could also be in areas with a lot of curl the spores can be dormant multiple years so picking off leaves in one year would not eliminate the disease due to year-old spores waking up.
Scott,
My reading was that the spores are long gone before the leaves sprout out, but this was in California and not the east coast. So perhaps a persistent freeze merits different treatments?
Hmmm, someone should get to the bottom of this. No time for searching this morning for me. Got to go spray.
Here is a pretty good page describing it:
http://eol.org/pages/188590/details
According to this page the spores can survive on bark and bud scales so removing leaves is not likely to help. The real question is if spores can be created there, if not then picking off leaves before they make spores should eventually remove all spores. According to the article shoots and fruits are also susceptible and it could be that is where spores could be created not on leaves. But I have never noticed any shoot infections. Maybe I had small enough outbreaks that the shoots never got seriously infected.
“The disease cycle starts when the overwintering bud conidia/ blastospores/ yeast cells come in contact with the young leaves. These structures overwinter in the bark and bud scales of the tree and acts as the primary source of inoculums.”
“Removal of the diseased leaves won’t help much because the pathogen survives in bark and bud scales.”
Thats the remark I was paraphrasing above. What is not made clear is how there is going to be pathogen on the scales if you have cut off the lifecycle by not letting it sporulate. Either it is from surviving multiple winters or because of an infection on a twig.
Perhaps for mild infections there will be little in the way of twig infection so you can cut it off by removing all the leaves. But for more serious infections there will be enough from the twigs and removing leaves may not help appreciably.
“This fungus is believed to survive the winter by staying on the surface of the new host plant, such as on bark or buds.[4] In the spring, new buds are infected by the conidia as the leaves emerge from the buds. The disease does not occur every year, as it requires a minimum of 3mm of rainfall followed by at least 12 days during which the developing conidia remain damp and at temperatures below 19°C.[5][6] The fungus has higher infection rates following cooler, damper winters.”
Yes I had read the same thing as well. Whats your point? The bit about the disease not occurring every year?
Condia can’t last forever so if there is no source of fresh condia the infection will eventually end.
Infected leaves develop a whitish bloom as the infection progresses. This bloom consists of asci that break through the cuticle of the leaf by way of lysis.[3] One ascus contains eight ascospores that create conidia, which are ejected in early summer and moved by rain and wind.
This indicates that the condia above that are starting the infection in the spring are created by asci on the leaves. If there are no infected leaves left there are no asci so there are no fresh condia so the disease dies out.
Sorry for going off topic but does peach leaf curl effect nectaplums like Spice Zee? I have one coming soon and wonder if I should hit it with copper?
Yes,mine has a bunch of the stuff,even after spraying about four times with Bonide’s Fung-onil from Fall to early Spring.So,I don’t recommend that brand.I’m going with Copper next year.Possibly a larger dosage will work with Fung-onil,but a person has to live with the results for a year if it doesn’t.
Speedster,I’d spray anything with a Peach or Nectarine in the makeup. Brady
Thanks. Should I just add the copper to my dormant oil?
Sure,but only spray if the plant is still dormant.The nursery might have already treated the tree. Brady
I spray my trees with copper hydroxide (Kocide 3000) 5 times per year and only two of those are during the dormant stages of the deciduous fruits.
Richard,
What diseases are being targeted? Brady