Dormant oil

[Prot1]

First time poster and here it goes! My question is about applying dormant oil. I had a customer call me about treating all his trees/shrubs. I was under the impression that the leaves needed to have fallen before applying dormant oil. My customer informed me that tg/cm always applied his DO at this time of year. Am i mistaken on having the leaves off the trees or was he misinformed? He pretty much told me in other words that tg/cl would know best being a big company and all. Whos right here and what should i do? Treat now or wait until the leaves fall. Any help on this would be greatly appreciated.

[Grassmechanic]

what are you treating?

[kickin sum grass]

I am not a tree and shrub man but here in Ohio nobody ( that I know of) sprays DO until February.

[Ric]

Dormant Oil is a soft leaf, hard leaf thing. % of AI, pest, time of day and irrigation factors all play a part.

I have a small nursery and spray 1 % fine oil in middle of summer late in afternoon. Irrigation washes it off the next morning. Some soft leaf plants will defoliate if sprayed with oils.

[xpnd]

I always thought of dormant oil associated with fruit bearing trees or in the above case where damage to the product would make it less appealing to a potential customer.

[Ric]

xpnd

Dormant oil is an insecticide that works by clogging the breathing tubes of an insect. Generally it is made from paraffin and bio-degrades in the soil. Many people mix it with insecticidal soap and this combo makes a great cocktail for most ornamentals and will get most surface insects on a plant. Insecticidal soap works by causing insects to lose there skin and die it also has Fungicidal properties just like any good anti bacterial soap does. The tree hugger should love this cocktail because it has little or no impact.

Problems are some soft leave plants also get there breathing tubes clogged and the leaves die. Oil on leaves is just like baby oil on your skin in the hot sun. Plants get Sun Burn Too.

No I did not use scientific words in this post because I wanted to make sure everyone understood how Soap and oil works. It is very safe to use and you could take a bath in it so I think the organic forum people should like it also.

[GroundKprs]

The beauty of soap and oil is that they are contact insecticides only. Any beneficial insects landing on the plant after treatment are not affected. The weakness of soap and oil is that they are contact insecticides only. Any harmful insects landing or emerging after treatment are not affected.

The weakness is not important in a dormant oil treatment, because it is done when insects are not active. Dormant oil, properly applied, can smother all life stages of most damaging insects, however they are overwintering. For example, a good dormant oil app with get much better control of euonymous scale than any chemical insecticide at any time, in my experience.

[Ric]

Aah Mr Jim

Don't forget the lemon flavor. Sorry I don't have the time to look up some University Study. But Lemon smells help keep bugs away.

[Prot1]

Thanks for the replys guys. I was also under the impression that it could cause certain trees to defoilate. I went ahead and treated the trunks and branches as best i could. As fas as timing on the DO i also will be applying this in early spring to smother the overwintering insect eggs. Again thank you all for the responses.

[xpnd]

Maybe I'm from the old school but I thought that DO was used to treat relatively stationary insects such as scale primarily on fruit trees. I know that there are different weights of DO that can be used at different times of the year but I still question the generalized use of DO in the landscape as a regular treatment. Certain companies in my area sell DO as part of the basic treatment plan. DO on plants such as Bufords, Indian Hawthorne, Yaupons, Boxwoods Oaks, Ash, Redbuds, which make up 95% of the contract landscapers installation package is IMHO a waste of my time and the customer's money. There is not a noticeable or observable improvement in quality that 99% of the customers can detect. I would rather upsell a service that the customer can see a noticeable improvement post application. (However I will always sell something if the customer demands a service because s/he knows more than I do.)

I am far from being a tree hugger however I am a big believer that a plant growing under the correct cultural and environmental conditions will have many pest problems that exceed the economic threshold treatment levels requiring the use of pesticides on a regular, be it annual, quarterly or monthly basis. I live in N. Texas. Those individuals that want durable and lasting landscapes should not be planting azaleas, junipers, eastern dogwoods or any other plant that is not adapted to our alkaline soils or host of wonderful insects that attack these stressed plants.

[1grnlwn]

I know very little about DO. But I do know a little bit o bout TG/CL. My customer informed me that tg/cm always applied his DO at this time of year. Am i mistaken on having the leaves off the trees or was he misinformed? He pretty much told me in other words that tg/cl would know best being a big company and all. They do "know best" but they do not "do best". They would apply DO to your car in they thought they could get away with it. A guy that worked for me got fired from TG for refusing to apply a second round of DO which was basically water. Good info on the DO though.

[Relly]

The main thing in regards to Horticultural Oil - be it applied as a dormant treament or a summer treatment- is to refer to the label. Some tress should not be treated due to adverse effects, which are listed on most labels. Likewise, Hort oil applications are to be avoided in the spring and the fall due to potential negative effects to the plants during the transitions.

Therefore, in response to correct timing for "Fall" dormant treatment, it is recommended that you wait until you have had cumulative 40 hours of below freezing temps. This can be monitored via the internet...find a local temp reporting site for yopur area that lists recorded temps by the hour. Count all #'s less than 33 and when you reach a total of 40, you should be set to go.

Generally, after 40 hours of freezing temps and the trees have 'hardened' off for winter, thereby lowering risk of oil damaging plant tissue. Note, as we get into Fall, one night we may reach 32 degrees for two hours one night, 1 hour the following night, 3 hours the next.....these are the hours we add together to get to forty. Understand?

When you look at early Spring Dormant Oil, make sure it is applied prior to bud swell, to avoid killing the buds. Both times of the year, you need to be sure that it dries on the plant and does not freeze. As far as which is better, Fall or late winter....research the particular insect you are after. Some get better kill in early Spring and others in the Fall. Generally speaking, I have seen research going both ways...Fall is better...Spring is better. Personally, I like the Fall as I have seen less chance of tissue damage (after 40 hours freezing)...if I run out of time, I can finish the round on the other side of winter. If the treatment is set for late winter, and I get behind and the weather does not cooperate and then the buds swell, the treatment has to be cancelled and therefore we have to wait for next window.

Also, read the label to see what pests oil is good for. The nozzle-head approach of spraying all trees and shrubs is a waste of time and money. Know what the oil is good for, inspect the landscape to see where the application is needed and apply accordingly. We should be well past the days of blanket spraying. Oil hurts some plants. Oil is effective on certain pests. Oil is effective at certain times of the year depending on pest. It is not a kill-all blanket type pesticide.

[Island Lawn]

Good Info!

"No I did not use scientific words in this post because I wanted to make sure everyone understood how Soap and oil works."

I apprectiate the effort.