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Dormant spraying is a very important action to take in preventing damage by insect pests, fungus, and disease. Codling moth, for example, is a common pest of apples and pears, and Peach Leaf Curl is a common disease of peaches and nectarines in California. Applying Horticultural Oil and Fungicide/Bactericide three times during the dormant season will greatly reduce the chance of infestation.
You can use the following guidelines and holidays as a reminder for spraying:
The first spray should be just after most of the leaves have dropped (Thanksgiving), the second at full dormancy (New Year), the third at bud swell (Valentine’s Day). The holidays generally correspond with the life cycle of deciduous plants, but always use your own observation to decide when to spray. It is also wise to research the specific species of fruit or nut for particular needs and precautions in regards to dormant spraying.
Peaceful Valley carries three choices for fungicide and/or bactericides:
Lime Sulfur, Sulfur, and Copper. Choose one along with the horticultural oil for dormant spraying.
We have offered information below for general information on each. However, the information provided is not meant as a substitute for the label information. Always read the label completely before spraying anything! Often, there are details and exceptions listed that you should be aware of. For example, Apricots are not listed on the Lime Sulfur label, because it should not be used on apricots! (Use copper for apricots instead).
You can read the full label information for each product Peaceful Valley carries at www.groworganic.com or visit our retail store.
Also called dormant oil, insecticidal oil, narrow-range oil, superior oil.
Active ingredient: Paraffinic or Petroleum oil.
An insecticide and miticide used to kill soft bodied insects such as aphids, thrips, scales, and mites. Also smothers insect eggs (including coddling moth eggs). Must have contact with insects/mites or eggs, not effective after it dries. May be applied while plants are dormant or as a foliar when not dormant. Can be mixed with Lime Sulfur, but only when plants are dormant.
Low, but “will kill soft-bodied predators or parasites exposed at the time of application”
Active ingredient: Calcium polysulfide.
A fungicide and miticide used to control powdery mildew, apple scab, and other fungal problems. May also control some overwintering insects as well as mites. From UC IPM Online, “Lime sulfur is primarily used for a dormant or delayed dormant treatment. It can cause injury to trees if applied after budbreak in spring or before mid October to early November in fall. Don’t apply with oil before November 15.”
“High. Corrosive to eyes and harmful if swallowed or absorbed through skin”
Low to moderate
Active ingredient: Sulfur.
A fungicide and miticide used to control powdery mildew, brown rot, rust, and other fungal problems. Also helps control spider mites. From UC IPM Online, “As a fungicide, sulfur protects only healthy plant tissues and must be applied before the fungi arrive and begin the infection process.” Sulfur should not be combined with oil or within 30 days of oil application unless plant is dormant.
“Low oral toxicity but highly irritating to skin and eyes”
Low to moderate
PVF&GS product: Kumulus DF Sulfur (PFM620)
Active ingredient: Various, including metallic copper and copper oleate.
A fungicide and bactericide used to control a wide variety of fungi and bacteria including peach leaf curl, shot hole, and leaf blight. From UC IPM Online, “Must be applied as a protectant before the fungi arrive and begin the infection. May be used as dormant sprays or in the spring. Do not mix fixed coppers with other pesticides as plant injury can result.”
“Causes severe eye irritation and can injure eye tissue; can cause skin Irritation”
Highly toxic to fish
PVF&GS products: Microcop (PFM315)
*All quotes from www.ipm.ucdavis.edu
vickie boyd Says:
Nov 27th, 2008 at 7:01 am
What can be done about ants that possible eat fruit tree buds in early spring?
David Edrington Says:
Nov 30th, 2008 at 11:49 am
Can a potassium bicarbonate-based fungicide such as GreenCure be mixed with horticultural oil for an effective dormant spray.
Amber at Peaceful Valley Says:
Dec 2nd, 2008 at 1:07 pm
So something is eating the leaf buds on your trees or the flower buds?
Often when ants are present it’s because they are feeding on the honeydew that aphids or scale secrete. If you see ants when the trees have leaves also look for aphids or scale they might be doing damage.
I’d be surprised if there are ants on the trees before there are leaves but let me know if that’s the case.
To control aphids and/or scale use a horticultural oil spray such as our Saf-T-Side spray Item POP807.
Hope that helps! Thank you for growing organically!
Amber at Peaceful Valley Says:
Dec 2nd, 2008 at 1:39 pm
Yes Potassium Bicarbonate can be mixed with oil and used as a preventative fungicide during the dormant season. This is from the UC Davis IPM website (Click Here to visit):
““Bicarbonates. A potassium bicarbonate fungicide (Kaligreen) is also available for powdery mildew control. It is registered for a wide variety of crops including most fruits and berries and is primarily a protectant material but has some eradicant activity. A simple fungicide can be made at home by combining 2-1/2 tablespoons of horticultural oil (Sunspray Ultra-Fine Saf-T-Side etc.) in a gallon of water and adding 4 teaspoons baking soda. This solution is sprayed on plants to prevent powdery mildew infections. Sprays of both potassium bicarbonate and baking soda can injure the plant so use these materials with caution. Also baking soda sprays can have deleterious effects on soil structure and should be used sparingly.”“
I don’t know however how effective it is (verses Sulfur or Copper) for fruit trees. I’ve seen it mentioned often in connection with Powdery Mildew but not with things like Peach Leaf Curl. Perhaps it depends on the nature of the fungal problem you are dealing with. Potassium Bicarbonate would fall on the weaker end of the potency spectrum. Here
Zack M. Says:
Dec 3rd, 2008 at 4:07 pm
In regard to fruit trees could horticultural oil be mixed with Bordeaux mixture or should these be applied separately during the dormant season?
Jan 18th, 2009 at 10:35 am
“Hello - please let me know where you have comparable information using organic methods (that will meet NOP WSDA OMRI - allowed restricted or prohibited materials ) - for managing the dormant season spray treatments for fruit / nut trees and bush or vines such as grapes.
Amber at Peaceful Valley Says:
Feb 5th, 2009 at 10:59 am
The article you are referring to is for organic methods but directed towards smaller scale growers. The same types of dormant materials mentioned that may be OMRI listed are:
The copper we carry Kocide was not OMRI listed at the time of printing our catalog. As with all certified products including those listed above you should check with your certifying agency on whether or not the particular products are still listed as status may change.
Peaceful Valley is also not allowed to give advice just information on products. Here’s a couple of links for organic consultants if you are interested:
This website provides excellent information on dormant spraying and was used extensively in the article we posted on our blog:
Hope that helps and thank you for growing organically!
organic bare root trees and garden tools | Organic Says:
Nov 25th, 2009 at 9:50 am
[...] a look at this article for more information on dormant [...]
Feb 2nd, 2011 at 12:14 pm
I would love to find something for coddling moth. Mostly in apple trees but also pear and walnut. I have about 8 trees total that would need it. MUST be on OMRI list or otherwise allowed for organic certification. I would really like to use those fruits. But I won’t use petroleum. Is there anything else? Thanks.
Feb 2nd, 2011 at 4:23 pm
Cyndi Here’s a list of our codling-moth-control products:
Hope this helps!
Charlotte from Peaceful Valley Says:
Feb 13th, 2013 at 1:45 pm
Tom Perri asked on a duplicate of this post: “I lost directions to the lime sulfer what is formula to water. and how much oil can be added”
Tom, It’s important to read the label on the lime sulfur product to get the formula. Here is a link to our products with lime sulfur http://tinyurl.com/axgugc7
Amber says in this article that oil can be mixed with Lime Sulfur, but ONLY when plants are dormant.