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Fungicide timing questions

Posted by chadinlg 9 (My Page) on
Tue, Mar 2, 10 at 14:55

Hello, the instructions for timing on fungicides say to apply before bud break or at bud break, or sometime before fruit set or petal fall. What are the consequences of missing these times ? (other than just not being very effective !)

For example if I am using Daconil and spray after bud break, but before fruit are present this should be OK, but if small fruit are present are they contaminated and not fit to eat later ?

The same question goes for fixed copper, though I can't imagine this is toxic.

I have a sulphur based fungicide as well which can be used "anytime", if there are issues with fruit safety, I suppose I should use this whenever fruit are present ?

The trees I am spraying include apple, pluot, nectarine, peach and cherry. My main issue is leaf curl, and brown rot with the cherry.

Thanks,
Chad


Follow-Up Postings:

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RE: Fungicide timing questions

I was planning on spraying fungicide (Ortho Garden Disease Control) on my peach trees this spring to control scab/leaf curl, and was going to spray before the buds break open, since this is when you need to target the leaf curl. At petal fall and after I was going to use Bonide Fruit tree spray for insecticide and fungicide coverage, since you're not supposed to use the Ortho after fruit has formed. Does anyone want to critique my plan? I know there are more powerful sprays, but I don't think I need anything more powerful. Scab was my worst issue last summer.


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RE: Fungicide timing questions

Hi Chad-
Since I don't use Daconil, I'm going to have to let one of the guys who does use it answer your question. Where are you located?

Kellascat-
I'm not familiar with Ortho Garden Disease Control, but I have learned to hate the Bonide Fruit Tree spray. Below is an except from a post I made about a year ago... It pertains mostly to apples, but you'll get the idea:

Many people on this forum (and I can now add myself to this list) are not big fans of all-in-one fruit tree sprays. The reasons are:

1.) The quantity of some of the ingredients is often insufficient to actually accomplish the task. Take for example the quantity of Captan in there. Many people here have argued that it is not nearly the strength required to be effective. Compare the quantity in there with that on the plain Captain container.

2.) In the all-in-one spray, you are often spraying chemicals that you do not need, for pests and diseases you do not have.

3.) The all-in-one says it controls things that it does not. It says it controls Cedar Apple Rust, but with its only active fungicide being Captan, it can not, as Captan does not control CAR.

The only thing Ive found it that it possibly did for me was possibly control Plum Curculio, but even that I'm not sure of.

Whats the alternative you ask? Indentify your pest and your diseases and treat them individually.

What types of trees are you spraying? Leaf Curl = peaches? Anything else? What types of insects are you trying to fight? Where are you located?

-Glenn


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RE: Fungicide timing questions

  • Posted by olpea zone 6 KS (My Page) on
    Tue, Mar 2, 10 at 15:39

The active ingredient in Daconil, and probably also in Ortho is chlorothalonil. Chlorothalonil applied before bud swell controls peach leaf curl. Applied after bud swell, it controls early brown rot infections, called blossom blight. It is not used after shuck split for reasons of phytotoxicity and possible residue issues. For later brown rot infections on cherry and other stone fruit, Montery Fungi Fighter is the most powerful homeowner product, although many times Captan will also do a good job. Scab on peaches is pretty hard to discern from bacterial spot. If scab is truly the problem, early sprays of Ortho won't cure it, since the disease occurs throughout the season, unlike apple scab which is possible to control with early sprays. Bonide spray may, or may not have enough Captan to control peach scab. It's probably a better idea to simply buy straight Captan for scab control, since Bonide is also a pretty worthless insecticide.


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RE: Fungicide timing questions

>and probably also in Ortho is chlorothalonil. Chlorothalonil applied before bud swell controls peach leaf curl.

Yes, and thanks, that's what I was aiming for.

I was under the impression that early sprays of Clorothanil would also kill the scab fungus?

I don't have much brown rot, and just a few worms which I don't mind, but the wife does. My biggest issue is scab, and I'm pretty sure it's scab and not bacterial spot because the leaves are not affected at all. That's why I think a few applications of Bonide might do the trick after petals fall. After reading what you said, maybe I'll spray Captan around July 1st.


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RE: Fungicide timing questions

  • Posted by olpea zone 6 KS (My Page) on
    Tue, Mar 2, 10 at 18:28

kellascat,

In my previous post, I was still writing while Glenn was posting. After reading Glenn's posting, he was right on. Glenn doesn't give himself enough credit, he is really more knowledgeable than he lets on.

Scab on peaches requires continual sprays of an effective fungicide. Apples are different. For apples, there is an initial spore release, that if can successfully defended against, can defeat the whole disease. Commercial apple growers are encouraged to take strong measures against the initial spring release of spores. For peach scab it's a bit different. Peach scab must be treated throughout the season. The fungus starts out as a small spot and develops into what looks like a scab. It requires season long control.

Again, I'm not that big of fan of Bonide. It contains captan and carbaryl at a low rate. Both these pesticides have some virtues in and of themselves, but in Bonide, they contain low rates. Captan is a good fungicide for peach scab, at full rates. Carbaryl (Sevin) is good for some pests (mainly Japanese and other beetles) but not really a strong tool against Lep. moths.

One spray of Captan at full strength may take care of your scab problem, I don't know. Generally spray guides recommend repeated treatment for peach scab until about 45 days prior to harvest.


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RE: Fungicide timing questions

Hi, referring to my original post, I am located in the S.F. bay area of California. My issues are with Peach leaf curl (peach and nectarine) and brown rot in cherries. I have not experienced scab yet.
Daconil does contain Chlorothalonil.
So to be clear if I spray Daconil just after fruit are set, the only issue is I may have some plant damage (phytotoxicity), but minimal residue issues on future ripe fruit.
I have not used Bonide orchard spray before - thanks for the warnings about it's possible lack of effectiveness.
If I have to spray late, would it be better to use fixed copper vs. Daconil ?

We are having a lot of rain this year so finding a good time to spray is difficult. The Cherry is just starting bloom, Nectarine and Apple not yet, and Peach has been in bloom for over a week. I sprayed this Sunday, and then we had 2 clear days before more rain today.

Chad


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RE: Fungicide timing questions

  • Posted by olpea zone 6 KS (My Page) on
    Tue, Mar 2, 10 at 21:18

Chad,

For leaf curl (PLC), you must spray while trees are dormant to have effective control. Once the growing season has started, it's too late, as the disease is systemic and no fungicide will help (copper or Daconil). If peaches are already blooming, the opportunity window for spraying has passed.

Copper is not effective against brown rot. Use Captan, or preferably Montery Fungi Fighter for cherry brown rot. Spray for brown rot once the fruit sizes.


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RE: Fungicide timing followup

  • Posted by olpea zone 6 KS (My Page) on
    Tue, Mar 2, 10 at 21:42

Kellascat,

To double check, I looked up peach scab in the Midwest Pest Management Guide. It says:

"Fungicides are especially important at shuck fall and should be continued every 7 to 10 days until 40 days before harvest as labels permit."

Of course these recommendations are for commercial growers. You will likely be able to get by with less, but this will at least give you an idea of appropriate spray timing.


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RE: Fungicide timing questions

Thanks Olpea! I try to study the few pesticides that I'm using, but often, that's where my knowledge ends, and thus my humility. When it comes to these chemicals, most of what I do know comes from my own research, and then studying (and taking notes on) the Olpea, Harvestman, Jellyman, & Michael357 postings! The Bonide FTS holds a special place in my heart because I believe they wasted my time and money (to the detriment of my trees) so I lead my own little crusade against them! I also usually heed Harvestmans gripe about people not divulging the amount of experience when they make a recommendation. Anyway, thanks again for the props! -Glenn


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