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Friday - July 20, 2007

From: Plano, TX
Region: Southwest
Topic: Seasonal Tasks
Title: Toxicity of horticultural oils
Answered by: Joe Marcus


Is T&S dormant oil spray a toxic product? Our church (Prairie Creek Baptist in Plano, Texas) is transitioning to organic/native landscape. This is the product used by the current lawn service. Also, we would appreciate any other information to help us make this transition.


Since we know of no brandname, T&S, we are assuming you mean trees and shrubs. This would make sense because trees and shrubs are the landscape elements that you would spray with dormant oil. The term dormant oil speaks more to the season in which it is applied -- during trees' and shrubs' dormant season -- than to a particular kind of oil. In the past, dormant oils were all petroleum-based, rather heavy oils that had to be sprayed in warmish weather during the winter. Scale, aphids, mites and other overwintering insects are the target pests for winter-application of an oil spray. Petroleum-based dormant oils can damage green (non-dormant) tissue. So winter annuals such as pansies, snapdragons and ornamental crucifers are often severely damaged by overspray or spray drift.

The toxicity of any dormant oil, or any other horticultural oil for that matter, can vary from product to product. So it is very important to fully understand the toxicity of the specific product that is being applied. Pesticide labels and Material Safety Data Sheets (MSDS) are your primary sources of information for pesticide use, safety and toxicity information. Your lawn service company must have MSDS sheets on file for each material they use. They will provide copies of those sheets to you at your request. If you have concerns about the safety of the material that is being applied to your church's landscape, you should meet with a representative of your lawn care company to discuss those concerns and look for solutions to any problems you identify.


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