I sprayed copper twice this dormant season and still got some PLC on my nectaplum. Thankfully, it’s dry now. All of the affected leaves have dropped and no more PLC!
What copper do you use? I use copper hydroxide. One spray a season is sufficient.
That’s what I use, with horticultural oil. Even though I sprayed 3 times this year I still have some curl going on due to all the rain this year. Most tress are dealing with it well though
Which product are you referring to? TY
I use Kocide 3000.
Chlor. is a very widely used fungicide on turf with a great deal of it being applied to golf courses all over the U.S. If the stuff posed a big threat to fish and other marine organisms I would guess I could find more about it on searching for info. The relative tiny amount used in a home orchard just doesn’t seem to me to be an important issue, although if there is standing water under the trees I would be concerned. However, presumably hundreds of thousands of acres of golf courses are being routinely drenched with the stuff, so discretion on the part of home orchardists will not have much bearing on the health of our planet in any case. Here’s a study I found with some info.
http://www.cdpr.ca.gov/docs/emon/pubs/fatememo/chlorothalonil.pdf
If I wasn’t getting adequate control with copper I would definitely move up to chlor and probably back down to copper once I had control.
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Yeah, chlorothlonil and copper are both toxic to aquatic organisms. It totally depends on what aquatic species is in question. There is a fairly wide variability in lethality to the compounds in question for various species of aquatics.
Generally speaking chlorothlonil is quite a bit more toxic than copper for water dwellers. Mostly chlorothlonil is measured in a 96 hr Ld50 in ug/L, whereas copper is measured in mg/L. In this reference, ug is ppb, vs mg at ppm.
That said, as Alan points out, copper doesn’t ever break down. Aquatic organisms depend on the copper to settle in the silt for their safety.
Either one is safe to use, imo, as long as basic cautions are observed.
Copper is required at a higher rate for disease control. About twice the poundage, so just because one is spraying copper shouldn’t give a false sense of security that it can’t harm fish.
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My curl problems are bad and getting worse this year. Every week more and more leaves are affected. I’ve fertilized twice with a high nitrogen granular fertilizer but new growth hasn’t begun yet
Should I spray the infected and uninfected leaves with fish fertilizer? (The only liquid fertilizer that I have other than some old Miracle Grow that I may have hanging around)
Also what should I do about the peaches on the tree? I was doing some thinning yesterday and some of the branches had no leaves and lots of peaches. Many 6 or 8 inch long branches had 6 or 8 peaches but not a single leaf. I was thinning like I would do by leaving one peach every 6 or 8 inches, but usually there are leaves all over the branch.
Should I remove all the peaches if there are no leaves or should i just do normal thinning and hope that the new leaves backfill the PLC infected leaves?
I’m pretty sure the roots are delivering adequate N. to the leaves- even infected ones, I assume you’ve gotten quite a few warm days like we have in S.NY the previous 2 weeks (not at the moment). Foliar apps just speed the process a few days and it isn’t helpful to overdo it.
Trees can absolutely defoliate now and rapidly replace the lost leaves. The sooner you thin peaches the more energy there will be for this (once again, assuming). You could thin to one peach every 4-5 inches with the intention of eventually making it 10" at least. If tree recovers enough to produce, you should probably be very conservative about how much fruit the tree should invest in. That will not only be better for the tree but also fruit quality.
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A peach tree set so much fruit even on branches or twigs that have no leaves.
Besides the recommended spacing per peach and getting rid of Siamese twins, I take off peaches on twigs that cannot handle fully grown peaches and peaches on branches that have no leaves.
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I used copper root killer (blue crystals) mixed with water on my peaches…no curl on anything.
I strongly disagree with recommendations to use only high nitrogen fertilizer. Maintaining a strong ratio of potassium to nitrogen is essential to tree health. We use soil fertilizer with feather meal and potassium sulfate, and we use foliar spray or fertigation with kelp and fish. We have relatively minimal leaf curl, although the early varieties got a bit. Then a spray with lime sulfur or copper in November and/or right before bloom does the trick.
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You needn’t strongly disagree without knowing the details. Often people mulch with woodchips or something else that insures more than adequate K. My problem at my own orchard is that too much K may be restricting calcium intake of apples creating corking. All fertilizing theory is local.
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Last year my Redhaven had leaf curl bad. It lost 80% of its leaves. Sprayed it with Miracle Grow liquid fertilizer twice and by Sept it was looking much better. Sprayed with copper after leaf fall and again in early Spring. Checked that tree today and there was 0 sign of leaf curl.
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The curl on my Harrow Diamond on Krymsk.1 has gotten pretty bad, even after a round of picking infected leaves off and seeing a new flush of growth.
However, Loring on Lovell seems to have outgrown the problem.