Using copper spray

keepitlow(6)March 5, 2009

I think Don mentioned he used copper spray on his peaches. I had a few question about this method.

How safe is copper spray? Does much of it get left on the peaches?

Can copper spray be used on most fruit trees?

How often is copper spray applied?

Can the same thing be done with neem oil in place of copper spray for a more organic method?

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Scott F Smith(6B/7A MD)

Copper is fairly safe for humans. It is less safe for various critters in the soil such as earthworms. The problem is that copper can build up over the years since it doesn't wash away and reduce earthworm populations.

Copper is only sprayed up to shuck split at the latest, so there is basically none on the peaches at harvest time.

Copper can be used on all fruit trees in dormant season. Early in the spring it can be sprayed on many types at more dilute quantity, but most trees do not like copper at all as the season progresses - it will damage the leaves. The only exception I have found is grapes which can take copper all year.

Copper as a dormant spray is applied once per year, or more if the diseases are worse. I have been using it twice, just as the leaves fall and just before the new ones come out in the spring, because I got bad shot-hole. If disease problems are bad, dilute copper sprays can be applied before and after bloom on peaches. As I mentioned above don't spray it after shuck split.

Neem oil is not much of a help on peaches. It is good for the same things oil sprays are good for: aphids, whiteflies, powdery mildew, etc, all things that are not big problems on peaches. Copper is certified organic for what its worth.


    Bookmark   March 5, 2009 at 1:01PM
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I think to clarify on the above--

Copper spray is used for diseases, like peach leaf curl.
Neem oil is good for killing certain bugs.

You would use one or the other, depending upon what problem you are trying to solve.

Carla in Sac

    Bookmark   March 5, 2009 at 2:06PM
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Where do you buy your spray from? The only thing they had locally was a small spray bottle that would not go far.

    Bookmark   March 6, 2009 at 7:53AM
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Scott F Smith(6B/7A MD)

I get Kocide 3000 for Johnny's Seeds. Kocide 3000 lets you use half the amount compared to Kocide 2000.

Carla, neem oil also helps certain diseases such as powdery mildew. In all the studies I have seen, the effectiveness of neem is in the same level as summer oil sprays, or a touch worse, and summer oils do help against some diseases. Even brown rot is dampened a bit by an oil spray. In fact, the Saf-T-Side oil spray is rated as equally effective on brown rot as is Captan. There is something special about that particular oil. I am going to be using Saf-T-Side this summer as a brown rot preventative.


    Bookmark   March 6, 2009 at 9:52AM
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Thanks. Will order some copper.

Do I spray the entire tree with copper from ground up or just the branches that will make fruit?

How late in the spring can I still safely spray the trees? Is it always a spring thing with copper and never spray in the fall?

    Bookmark   March 6, 2009 at 2:41PM
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Scott F Smith(6B/7A MD)

The places leaves or fruit will grow from are the most important to get coverage on, but diseases could be overwintering in other spots.

If you look above I addressed your latter question: peaches can be sprayed at dilute strength up to shuck split. The most important time to spray is the spring, doing a dormant spray just before the tree wakes up. I also do a fall spray since that helps against bacterial spot; if you don't have bacterial spot I would leave off the fall spray. The later spring dilute sprays also help against brown rot and bacterial spot; just don't do any after shuck split. My dormant strength spray for Kocide 3000 is 2 tbsp/gal and growing season its 1 tsp / gal.


    Bookmark   March 6, 2009 at 3:48PM
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Hey Scott: how did you come up with those rates? As you may know the only place the label makes any reference to Tbsp/gal is in the greenhouse and shadehouse crops section. I'm using Kocide 2000 whose A.I. is slightly higher. It states, "1Tbsp/1000 sq ft... is equivalent to 1 lb/acre". I weighed out 1 level Tbsp and came up with 0.54 oz.. 43560 sq ft / 1000 sq ft x 0.54 oz / 16 oz = 1.47 lb/A. My math may be wrong on that, anyone, please check it. There may also be a problem with the weighing but I was very careful. I've been having difficulty reconciling, "1Tbsp/1000 sq ft... is equivalent to 1 lb/acre" with the rates in the individual crop tables like, 6 - 12 lb/acre, using the label stated 400 gal "dilute" rates. Any comments are welcome. I wasn't a math major.


    Bookmark   March 6, 2009 at 7:52PM
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I think very few people who are not professional orchardists would know what "shuck split" means--can you translate for the homeowners?

Carla in Sac

    Bookmark   March 6, 2009 at 9:56PM
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These kinds of definitional questions can be easily cleared up by using your Google search. Takes about the same time as typing off a msg. and requires no reply. There is even a photograph of a Redhaven peach at shuck split.

Don Yellman, Great Falls, VA

    Bookmark   March 6, 2009 at 10:58PM
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Scott F Smith(6B/7A MD)

Carla, shuck split is just before the flowers fall off the peaches to the ground. The little baby peaches have grown big enough that the remains of the flower has a split in it.

Michael, I did a calculation using the numbers on the label as you outline above; its a pretty big guess. Suppose we pick 6lbs/acre; thats 6lbs/400gal, i.e. .015lb/gal = .24oz/gal = 1.5 tsp/gal by your weighing above. the 6-12lbs for apples then becomes 1.5-3 tsp/gal. My number for Kocide 2000 was 1/4c/gal dormant which means I must have assumed I was more concentrated, i.e. 100 gal per acre. I think I made that guess by measuring how many sq ft I was spraying with my 4 gal sprayer and converting to gal per acre. I believe Don is using 1 1/2tbsp per gallon of Kocide 2000 as a dormant spray and is getting good results, he just posted that on another thread. In fact I may be using more than I need to given his good results.


    Bookmark   March 6, 2009 at 11:22PM
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glenn_russell(6b RI)

I had planned on using 2 tbsp/gallon of the Kocide3000 along with a 4% dormant oil solution. But, I thought you could get away with less of the 3000, than the 2000? Does 2 tbsp/gallon of Kocide3000 sound too high for a dormant spray of apples? -Glenn

    Bookmark   March 7, 2009 at 8:15AM
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olpea(zone 6 KS)

Scott had a typo. Just to clarify shuck-split. It occurs after petal fall. Peaches have a small shuck that encases the fruit. You'll recognize the shuck after petal fall (flower petals have fallen off). The rapid expansion of the fruitlet causes the shuck to burst, or "split". Hence, shuck-split.

Good question Carla. I'm thinking Don's cranky because he never sleeps. If you'll look at his posts, you'll see they are at all hours of the night and morning. Don, when in the world do you ever sleep?

    Bookmark   March 7, 2009 at 11:49AM
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Hey, Glenn and Scott: after much labor, 1 epiphany and some hopefully flawless math and logic, I came up with this, See if it makes any sense for Kocide 2000.

The label states 400 gal/A water, that is the carrier. It also has various rates in lb/A of the Kocide. What in my mind is most important is the concentration of Kocide in the spray tank regardless of how many gallons you make up. The plant and the pathogen don't care if it takes 100 or 1000 gal to spray an acre and get thorough coverage, they care what the concentration is because that is what burns the plant and kills the pathogen.

So according to the following calculation -

(Lb Kocide x 453,592 mg) / 400 gal x 3.785 liters = solution concentration in mg/L (ppm). One pound = 453,592 mg.

Accordingly, 1.5 lb/A rate = 449 mg/L, 3.0 lb/A = 898 mg/L and so on. Also on the label under the section "Greenhouse and Shadehouse Crops" is the statement that 1 tbsp/gal = 1 lb/A over a 1000 sq ft area. According to my calculations and assuming Kocide weighs about 15,400 mg/Tbsp (I weighed mine), 1 Tbsp/gal = 4075 mg/L. The highest fruit tree rate on the label is 12 lb/A which as calculated previously would be 3592 mg/L.

The common factor in the label rate in lb/A in 400 gal and the Tbsp/gal calculations are that they are carried out to a final solution concentration which, as stated in the beginning, is what I believe is what must be done. Now if all the math and logic is correct, we can make up spray solutions of different concentrations that fit the need stated in the label.

By all means, please let me know if I'm wrong anywhere in all of this. It is important to me and anyone else that may take it to be correct.

Oh by the way, I don't think the % A.I. in Kocide 2000 (53.8) is much different than Kocide 3000 though it is significant.



    Bookmark   March 7, 2009 at 4:21PM
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olpea(zone 6 KS)

Noticed you plan to spray oil at 4%. Are you sure that's what the label says? My label says 2%, and at that rate it turns the bark dark. Just wouldn't want you to damage your trees.

    Bookmark   March 7, 2009 at 9:47PM
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glenn_russell(6b RI)

Hi Olpea-
I just double checked my "All Season's Horticultural & Dormant Spray Oil" label. It basically says for apples, during the dormant stage, use 4% oil (10 tbsp/gal or .625 cups/gal). But, after that, I'm supposed to back it down to 2 or 3% depending on the target. So, I think I'm OK. Though I did notice that Scott thought it was more like .25 tbs/gal here in this link. IÂm thinking itÂs because my oil is an all seasons oil? Let me know if think I still may have a problem here. This is probably the amount I used last year. I included an excerpt from the label below.
Thanks for looking out for me!

Hi Michael-
Yeah, I too was frustrated that the Kocide 3000 label didnÂt have a rate per gallon. I didnÂt even attempt to convert from the gallons per acre rate. IÂm probably going to take the "private applicators" class later this week, and was hoping to learn more in this area. Until then, I just planned on doing what others here were recommending. For example, above in this thread, also in the same link as above, Scott says heÂs using 2 tbsp/gal rate. For now, thatÂs probably what IÂm going to go with. I also plan to put down a disposable tarp to help keep the excess to a minimum. Now, if I could just find the right day to spray!

From All Season's Horticultural & Dormant Spray Oil" label: Apple:
bugs, European red mite, bud moth, leaf roller, apple aphids (except rosy aphids). Use
2% actual oil solution for mites, San Jose scale - Use 3% actual oil solution for scurfy
scale, leaf roller, bud moth, red bug, codling moth larvae. DORMANT STAGE of bud
development for all above mentioned insects, use 4% actual oil.

    Bookmark   March 7, 2009 at 10:30PM
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Don't feel bad Glen: I still have to prune first, then wait for a day to spray. The good news is I just drove an hour and 3/4 up to Kearney NE to get my shiny new orchard ladder on which to stand while pruning. Couldn't resist getting a new 17" long Felco lopper. Figures, it's raining tonight, new toys and I can't play with them in the morning!


    Bookmark   March 7, 2009 at 11:12PM
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A previous reply said copper is bad for earthworms. Keeping that in mind how little spraying can you get away?

Will one early spring spray of copper do any good? Or will it take a lot more sprayings to show results? I am not looking for perfect trees and fruit. but would like to control disease somewhat.

Also when spraying, do the trees need to be drenched or is just a light coating enough?

    Bookmark   March 8, 2009 at 10:59AM
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Scott F Smith(6B/7A MD)

keepitlow, copper is bad for earthworms after 20+ years of applying it regularly. The problem is it doesn't go away, ever, unless you dig up the soil. I am planning on continuing to use it for my dormant spray but I am trying to cut back on the active growth sprays (I was having to do many of those on my grapes). Given that Don is having good luck with 1.5 tbsp/gal of Kocide 2000 I will probably scale back to something like 1 tbsp/gal of Kocide 3000 this spring to also reduce the amounts. Kocide 3000 is the same amount of copper but it is more "active" so you get more mileage out of each copper atom. Minimizing copper amount is another reason to use Kocide 3000 over Kocide 2000.

Michael, the Kocide label dosage is difficult to apply to homeowners. Our spray equipment and style is very different from the commercial version. I think the bottom line is to apply the smallest effective amount. I was putting 1tsp/gal on my grapes in the growing season but noticed if I cut back to 1/2tsp/gal I got just as good a result so I recently switched to that. Going from 2 tbsp/gal to 1 tbsp/gal for my dormant Kocide 3000 will be a similar experiment. If its not looking good I will bump it back up.

Glenn, I use .25 cup/gal for dormant oil, not .25 tbs. I don't think there is any harm in putting too much oil on, there are no leaves to get injured. But on the other hand its a waste of product to use more than is going to help.

Olpea, you are right that the petals fall earlier than the main flower body which has the shuck on it.


    Bookmark   March 8, 2009 at 12:38PM
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glenn_russell(6b RI)

Hi Scott-
Sorry, the .25tbs was a typo. I meant .25 cup. (It was getting late!)
I agree... I wouldn't want to use any more dormant oil than necessary, even if it's relatively benign. I'll take your .25 cup into consideration, and probably back mine down a bit. I was just following the label.
That's good to know about the 20+ years for earthworms. I was wondering how long it would take.
Great info guys. Thanks!

    Bookmark   March 8, 2009 at 1:15PM
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Just to weigh in-
My Kocide 3000 rate is based on using 5lb./acre (3.5 -7.0lb. is suggested for scab/fire blight dormant control), which is exactly half of what most apple growers use when applying Kocide 2000. Most growers try to get 100 gal./acre to cover whatever they're spraying. That comes to .05lb./gal. which = 0.8oz./gal. = 1.6 TBSP/gal. Kinda sloppy - but this rate is definitely in line with what you are thinking about above.

    Bookmark   March 24, 2009 at 2:58PM
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Organojoe: I follow your calculations above. However what is confusing to me is the obvious difference in the spray concentration if you are mixing in 100 vs 400 gal of water. If an orchardist were spraying 2 year old trees vs 8 year old's, would they still use 100 gal in either case? If so, the spray concentrations would be the same, if not they would be different but still applied to the same land area. The reason I bring this up is that I believe (perhaps mistakenly) that the concentration is of paramount importance to nailing the target organism and also crop sensitivity, I.E. burning tissue. I don't want to be scorching my trees or applying a concentration that is ineffective. Maybe I'm over thinking this.


    Bookmark   March 24, 2009 at 9:45PM
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Alright - forget about what I said above - so much for my quick back of the envelope calc.(apparently in my world an ounce = fl. ounce). This is my first year with this product. I won't be spraying for another week or two so I hadn't looked that closely. I do see where concentration is 3.5-7.0lbs./400gal.per acre ground dilute. I guess then the calc. for a 5lb./acre rate would be 5lb. per acre/400 gal. per acre = .0125lb/gal. We are now talking about measuring impossibly small amounts as .0125lb. = .354g. I don't have anything that measures down that low. I wouldn't be surprised if we are down to a lot less than a tsp/gal. Another thing to consider is the uselessness of the application instruction where 1 TBSP = 1,000 square ft. for greenhouse crops. When spraying fruit trees we are dealing in cubic ft. so no relation can be derived.

    Bookmark   March 25, 2009 at 1:10AM
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For what it's worth here is a Kocide 2000 recommendation:

Also, I was able to figure out a 5lb./acre rate of Kocide 3000 using the application instruction where 1 TBSP per 1,000 sq.ft. = .5lb./acre by using a tree row volume calculation like the one from here (section 4.6):

Amazingly 1TBSP/gal = 5lb./acre rate for my orchard.

    Bookmark   March 25, 2009 at 11:27AM
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