Is it too late to spray copper?

General Fruit Growing
#1

I had it written on my calendar to spray copper around Thanksgiving. I have one tree in particular that gets PLC quite bad and a few other trees that get it in minor amounts. I read somewhere that is not nearly as effective if you spray too late because the trees bark contracts up and seals in the PLC diseases when freezing temps arrive. We already have had multiple freezing nights. Would it be better than nothing to spray now than to do nothing?

#2

No, I have not sprayed copper in the fall for years, I spray it mid to late Feb, with sticker and oil. I have been getting zero PLC with this. In a year that I sprayed in the fall only (and no sticker), I had a lot of PLC.

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#3

Care to mention the product or brand you use?

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#4

What oil and sticker do you use?

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#5

I usually spray right before the buds start to swell. To me later is better, so it does not have a chance to wash off and re-infect.

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#6

Are any of you spraying a certified organic product that has worked well for you ?

Does this one application before bud swell protect from PLC … and brown rot ? Black speck ?

Or do you do other applications after fruit set ?

I lost at least 300 peaches last year to brown rot. I have never seen PLC here.

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#7

I read most of this “low impact” spray schedule…

Cant see me doing anything close to that.
Talk about taking the joy out of growing stuff. I will just grow less peaches and more no spray stuff.

#8

Since Peach Leaf Curl requires …
“wetness from rain, dew, or irrigation for more than 12.5 hours at temperatures near 61°F" and “maximum infection occurs when trees are wet for 2 or more days.”(http://ipm.ucanr.edu/PMG/PESTNOTES/pn7426.html)”,
you may find these conditions occurring before Feb. due to variable weather patterns.
Here in PLC heaven, I need a fall and spring spray and one in between, depending on weather. Even then I still get some curl. In my cool maritime climate, PLC is a much more serious concern for me than brown rot.

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#9

Can someone suggest a brand of copper spray?

#10

I use Kocide 3000-O (copper hydroxide) alternating with Brandt Lime Sulfur.

#11

if you’re ok with a harsher chemical, ziram + sticker is recommended. ditto for lime sulfur, that’s a good choice, it’s benign except for being dangerous for the applicator. I do one of each of these:

  • CuPRO 5000 (off-brand kocide) + nufilm 17 sticker
  • lime sulfur (no sticker)
  • ziram + nufilm 17 sticker (timed as close as possible right before bud break)

PLC control is VERY different and more demanding in wet parts of the west than in other areas and many report copper alone being insufficient

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#12

Sure, I use Copper Octanoate (Bonide’s; 10% concentration; 4 Tbsp/gal), Monterey’s Horticultural Oil (5 Tbsp/gal) and NuFilm 17 (0.5 tsp/gal). I checked my orchard diary and below were the spray dates for the past few seasons:

2018: Feb 26
2019: Feb 21
2020: Feb 3 (this was a very warm winter and buds were swollen very early)

The only reason I am using this form of copper is that it is supposed to be the mildest on green plant tissues, and I used to spray copper (at lower dose) a couple of times during the growing season for bacterial spot, and I don’t want to purchase two different bottles of copper. I think other forms of copper should work as well if not better.

I mentioned this a week or two weeks ago to another poster, too much copper spraying is bad for one’s orchard, as copper is phytotoxic and it will build in the soil. I’d rather have a little bit of PLC on my trees than spray copper twice in a season. A low level of PLC is not a big deal, trees will quickly produce a lot of new foliage that is healthy and will go through the season as if they had nothing. Bacterial spot, on the other hand, comes in the middle of the season, and can defoliate 70-80% of the tree (with susceptible varieties), resulting in severe shock and major fruit drop, in severe cases a tree may die, so I had no choice with bacterial spot. Even then, in 2020 I switched to oxytetracycline instead of copper (but it is not as effective and alternating them is recommended). Finally, I used to live in Wilmington, DE, which is fairly wet and humid year round.

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#13

I took out quite few stone fruit trees for those reasons. There is no organics for brown rot and still a fair amount of loss using hard core sprays. I now see persimmon, pawpaw, ect. as more my speed. Still have a lot of stone fruit trees, just half as many as before. Brown rot has crushed my dreams of a stone fruit utopia.

#14

I always spray my copper in late Februrary or even early March (I concede that is pushing it). I always feared if I did it this early it would wash off and the things I’m spraying it for would reestablish themselves by bud break.

I should add that I am a pretty big fan of Copper. I’m certain it helps with a few things. What I am not a big fan of anymore is the horticulture oil. I have always sprayed copper and oil together. But to be honest, I’m not even sure what I’m trying to smoother with the oil in my part of the country. So I’m going to drop the oil this year…but definitely do a later copper. Good luck my friend.