I’m trying to treat leaf-curling plum aphids on my pluots. I would like to find a source for a dormant-use-only oil that contains emulsifier so that it’s ready to mix with water. I do not want an all-season oil (e.g. mineral oil). Golden pest spray oil and Stollers natur’l oil, would be perfect, but I can’t seem to find them in smaller quantities.
I have considered making my own, as has been suggested on this forum, (e.g. using soybean oil, detergent and water) but I don’t trust that detergent added to an unadulterated oil will function sufficiently well as an emulsifier.
Are there any dormant oils sold on the retail market (in reasonable quantities) that contain soybean oil (or other heavier oils) as their primary ingredient, along with an emulsifying agent?
What do you mean by true dormant oil? I mean what do you think makes them different than other oils? Early ‘dormant’ oils were heavy and not meant to be used during the growing season, but most modern oils being used are light and can be applied at any time. In modern parlance ‘dormant oil’ refers more to the time of application than an specific quality of the oil. If there is a difference is that you do a heavier application when the plant is dormant.
Most (all?) dormant-oil-in-a-bottle already contain an emulsifier to make it easier to mix. You pay dearly for that bit of soap.
I’m referring to what you call the “early dormant oils”. As you say, what makes them different is that they are heavier than the all-season oils. I want it to be heavy. I do not plan on using it during the growing season. The reason I want the heavy oil is that some folks on here have expressed the opinion that these heavier oils are more effective than the year-round oils when applied during dormancy. My understanding is that Golden pest spray oil and Stollers natur’l oil are both heavy oils intended primarily for dormant application (and delayed dormant).
I’m a bit confused when you say both that the early dormant oils were heavier, and that the only difference is in the application. My understanding is that there are heavier oils (such as soybean) that are not appropriate for application during the growth season, but they are appropriate for the dormant season. That is what I’m looking for.
Heavier and I forgot to add contained sulfur, which in concentration was harmful to green plants and as such only recommended for dormant use. One of the first refinements was to remove sulfur content after which they became ‘summer oils’ and ‘superior oils’.
Look at the labels, but most of the premixed oils are light, and what makes a dormant application is how thick you lay them down. Applied correctly they are very effective.
Under the “Reference” section there’s a thread for “Source for Supplies” which includes several sources for Pesticides. I think you may find what you want there. I see DoMyOwn has Hi-Yield that’s labeled as Dormant Oil for fruit trees. They have a few pages of Horticultural Oil.
Are there any university studies on mixing your own dormant oil with vegetable oil and detergent? I’m thinking about mixing my own but I wanted to be sure that it will be effective.
I didn’t see any results from studies,but here is some information about what Cornell University came up with for mixtures.
Dormant Oil Recipes
Several dormant oil recipes are available and help control pests on fruit trees. A dormant oil formula developed by scientists at Cornell University controls overwintering pests and foliar diseases. It contains 2 tablespoons of ultrafine canola oil and 1 tablespoon of baking soda mixed with a gallon of water. Cornell University scientists also developed a nourishing formula containing 2 tablespoons of horticultural oil, 1 tablespoon of baking soda, 1 tablespoon of kelp and 1 tablespoon of mild dish soap mixed with 1 gallon of water. Another dormant oil recipe contains 2 tablespoons of baking soda, 5 tablespoons of hydrogen peroxide, 2 tablespoons of castile soap – which is made from an olive oil base – and 1 gallon of water.