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scottfsmith

Dormant spray timing

Scott F Smith
16 years ago

I am curious when people do dormant sprays. I used to do all my dormant sprays on some random day mid-winter which had good conditions, but clearly this is not optimal. The advantage of a dormant spray is there are no leaves and you can put down a huge amount of oil and copper or L/S which would not be tolerated by the leaves. But, putting it on in midwinter will not be as effective because the diseases and bugs are themselves dormant. So the best times to spray is as early as you can in the fall, plus as late as you can in the spring (i.e. as early and late that you can do a full strength spray: leaf fall and green tip or thereabouts). There is in fact a good reason for this pattern: when the bugs and diseases are either "waking up" or "going to sleep" they are much more susceptible to the chemicals. Waking/sleeping are complex biological processes which can be more easily disrupted. There is also concrete supporting evidence for this in the advertised control of shothole on peaches (spray full-strength copper at leaf fall), for fireblight on apples (spray full strength copper at green tip), and for control of aphids on apples (oil at silver tip).

Anyway, I have slowly been moving to "fall" and "spring" dormant sprays away from the "winter" model, and now I am thinking to get even more effective control I want to push this to the limit and spray as early as I can in the fall, and as very late as I can in the spring (leaving enough leeway so I don't miss the window and risk damaging the leaves). This year I waited longer than I ever have to do my spring dormant sprays, I just finished all except the still-sleeping grapes. Some apples were past green tip but most were at silver tip and I could have probably waited a touch longer on them. I am spraying Kocide 3000 plus dormant oil on everything - the oil helps the copper stick better so even on trees not getting aphids I like to add it. I used to also add a sticker (Nufilm 17) but stopped doing that.

Comments?

Scott

Comments (15)

  • lycheeluva
    16 years ago

    I sprayed kocide on my stonefruit trees in November and in late february. I have had very bad problems with peach leaf curl in the past though had never used kocide before. I am wondering whether it might be an idea to add a 3rd spray next weekend. My stonefruit tree are showing the pink ends of their blossom.

    Is it too late to spray kocide at this time and is one limited to 2 sprays?

  • Scott F Smith
    Original Author
    16 years ago

    LL, curl is a disease responding best to a fall spray so you already did the most important spray for it. It is not that hard to knock down based on my experience so one spray anytime in the dormant season will probably work on it. Since it forms on the inside of the bud, after some point the spray will not help; I am not certain exactly when that point is. Make sure you are using dormant strength copper on it, which is about ten times the growing season strength.

    Scott

  • bart1
    16 years ago

    I'm surprised this thread didn't get more comments.

    Or is it just common knowledge that you should spray as late in spring as possible and as early in fall as possible?

    Bart

  • larry_t
    16 years ago

    Scott -

    Thanks for the information. I planted my trees just 3 years ago, and have been doing dormant sprays but hadn't really thought about the best time to do it. I just looked for a calm, warm day and did it. But, what you say makes lots of sense, so I'll be trying it.

    Thanks also for the reminder to combine the Kocide and oil. I remember reading about that before, but somehow this spring I sprayed them separately, which meant finding two calm, warm days.

  • glenn_russell
    15 years ago

    Hi Scott/all-
    As I was researching for my other dormant spray question, I ran across this thread. It sounds like I would have been better off to do the first of my 2 Kocide / dormant oil sprays back when the trees first went dormant. Since I missed that opportunity, IÂll just do mine in the next week or two.

    I think this is a simple question How do you know when the trees are dormant enough to do that first spray? Is it just when the leaves fall off? ItÂs hard for me to use that because some of my trees were still hanging on to their leaves until a couple weeks ago and they still might be on except a deer got them. (Damage wasnÂt bad stink spray hadnÂt been sprayed in a while, but actually made the deer do a decent pruning job for me once I cleaned up the bite cuts!) Or is it after the first hard frost?

    Also, as IÂve read in these postings, it makes sense to do your winter pruning prior to dormant spraying to reduce the amount of spray. So, whatÂs the best telltale to know that the tree is dormant enough for winter pruning, and then dormant spraying? Do you know about what date this usually is for you?

    Thanks as always for all your tips,
    -Glenn

  • marknmt
    15 years ago

    Are you guys talking about spring spraying now?

    It won't be spring here for two and a half months! I likely won't prune until Febuary.

    We're predicting the mid-teens this week, but it did warm up nicely today, to the mid thirties. Saves on the heating bill anyway, but the wood is frozen and there's snow all over too.

    By the way, why is it said that you shouldn't prune frozen wood?

    :-)M

  • glenn_russell
    15 years ago

    Hi Marknmt-
    Nope, not talking about spring spraying now, but rather dormant spraying. Scott and Jellyman were recommending 2 sprays of the Kocide & Dormant oil to control scab: One dormant, one at, or just prior to, bud break. In this thread, Scott was suggesting that the dormant spray would actually be better off done at the very beginning of the dormant season. I went out to spray deer spray the other day, and since the weather was comfortable and I had the time, I figured IÂd go ahead and winter prune. And, since I missed the early dormant season that Scott suggested, pretty soon it will be time for me to do my (1st) dormant spray. Take all this with a grain of salt IÂm still a newbie at all this.
    Ahh, yes, spring only 2.5 months away. :-)
    IÂm sure Scott will chime in soon. Thanks,
    -Glenn

  • Scott F Smith
    Original Author
    15 years ago

    Glenn, the apples and plums often hang on to leaves for a long time. You can dormant spray in late November even with some leaves left -- the plants are pretty much in dormancy already.

    Mark, I am enjoying your nice weather today as well, I'm in Montana now. Was pretty cold before today.

    Scott

  • glenn_russell
    15 years ago

    Thanks Scott! You 'da man!
    -Glenn

  • marknmt
    15 years ago

    Scott- where in Montana?

    If you get near Missoula you have to let me buy you a burger and a beer at the Missoula Club, and if you don't do alcohol they have good shakes.

    I figure the entire meal might set me back $8.00 if we spring for peanuts and leave a tip ... but I'm feeling expansive and don't mind a ritzy joint once in a while.

    :-)M

  • olpea
    15 years ago

    Scott's on the mark with fall and spring spraying schedule. Glen, on the question of exactly when a fall dormant spraying should occur, it probably depends on what one is spraying, and what one is spraying for. I have a problem with pear blister mite on pears. It was recommended by USDA pear breeder (can't remember his name now) that to control it with dormant oil in the fall, it should be done when the leaves were 50% dropped, then again in the spring. As I recall, it did hasten the dormancy of the pears. We'll see how they do. Remember oil is not supposed to be sprayed when there is a danger of freezing weather w/in the next 48 hours.

    On leaf curl, I've had trouble controlling it with copper. I went to two sprays of chlorothalinil (fall,spring) and had complete control. Last year I tried one spray in the fall (chlorothalinil) and had leaf curl pretty bad this season. Starting this fall, I plan to go back to two sprays.

  • Axel
    15 years ago

    Well, in my garden here in Santa Cruz, I am spraying this week as we have a very short window in the mild climate here.

    I had to manually defoliate many apple trees in order to get ready to spray. Some apple trees tend to be slow to defoliate since we practically never drop below freezing here, and this despite 800+ hours of annual chill. The cool temps 32-50F don't seem to be enough to entice the apples to loose their leaves in a timely manner. I don't spray Granny smith and pink lady since they seem to keep their leaves all year - they just molt.

    Those of us in warm climates have a very, very small window of time to Spray. I do it once around new year and I go at the peach trees a second time in Spring (early February here) to get peach curl. I don't spray anything else besides polysul (lime-sulfur fungicide), which is amazing for peach curl. I also do a second spraying in February on any apple trees that showed any signs of mildew the previous season.

    I will also spray my cherimoyas this year as the extended chill makes them more subsceptible to fungi. I've never done this, it will be an experiment to see if it actually works.

    Does anyone know what organic to spray on apricots? I've never sprayed them, but I've noticed there's some sort of blossom induced wilt that occurs in the Spring, it's not fireblight, it's called something else, I forget the name.

  • geraldo_linux
    15 years ago

    Apples and pears one spray at half inch green in the spring. Nothing in the fall. I don't contend with scab, etc.
    Peach and cherry in the fall when ninety percent of the leaves are off and the wind from the sprayer blows off the rest.
    Now having said that I have sprayed copper on cherries in the spring at Tight Cluster and even have friends who have sprayed at Open Cluster. When I ridicule them they reply they needed to get some on even if nothing more than to make themselves feel good. "Watta ya gonna do. It is now or never, at least until November." They think it does some good at that time. I'll bet it does. They have decades of experience and know their business. But I think peach is a different deal. I have more experience with peach and I think they need to be dormant. IMHO.
    I have sprayed dormant on apples when the flowers were starting to come out. Had to as earlier I had been sick or something. Just didn't use much oil as that can get into the flowers. Another case of not advisable, but what are you going to do. I know some who never put on a dormant oil at half inch green and always wait until Tight Cluster. They're reasoning that the bugs have hatched and out and crawling around. They get no argument from the Phds.

  • glenn_russell
    15 years ago

    Hi Olpea-

    Thanks for joining the discussion!

    For me, this dormant spray of Kocide3000 and oil is mostly to control Scab, and to control aphids and scaling insects. IÂll do another similar spray just before bud-break as per JellymanÂs recommendations.

    "Remember oil is not supposed to be sprayed when there is a danger of freezing weather w/in the next 48 hours"

    Good point. For my "All Seasons Horticultural & Dormant Spray Oil" it simply says "Make application when temperature is above 40 F" If IÂm patient, and I have everything ready to go, I can probably get a day or two like this in the next couple weeks. But, I doubt I could satisfy the 48 hour requirement at this time in the season. Hopefully that will be OK. Even if I do the spray back in November as Scott suggests (after I pick my mid-Nov ripening Granny SmithÂs), a 48 hour frost-free window may be difficult to come by.

    IÂve already got my late November calendar marked for next year.

    Thanks,
    -Glenn

  • djofnelson
    15 years ago

    I was rereading this extremely insightful thread and thought it would be helpful to other folks with a last dormant spray on their minds.

    Based on the above comments (and since half of my peaches are at first flower and I've got rain and/or cold temps predicted for the next 10 days), I'm hoping my single application of oil and Kocide 3000 in late fall handles my peach curl problem.

    Since I sprayed the same mixture on my plums, apricots, and cherries in late fall, that leaves me with my last remaining dormant spray (other than grapes) being applied to my apples and pears at somewhere between green tip and 1/2" green tip.

    Any thoughts?