Oil plus heat

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Discoloration and distorted growth often follow exposure to pesticides during hot weather. Herbicide and fertilizer caused this damage on the exposed surfaces of a hybrid tea rose. Oil is the base in most spray formulas, so even insecticides that are normally considered safe for use on a plant can burn when they sit on the plant leaf like coconut oil on a sun bather. 

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To applying pesticide when it's very hot or plants are dry.

Oil plus heat is great for saute but not a good thing for roses or tomatoes.

The rose foliage burned after a misty spray of liquid lawn weed and feed went a bit wide. The tomato reacted to spray that drifted as a neighbor killed weeds. Both may recover but their season will be lost.

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