Arborvitaes Damaged By Mix Of Chemical Treatments

Question From: C. Wheeler - Soddy-Daisy, Tennessee, United States
Q: Nancy... I had a lot of brown die off on the interior of my three arborvitaes so in October I mixed a spray of the Bayer Advanced Insect and Disease control, Volick Oil and Dawn in a miracle Grow Hand sprayer. I had read that in the winter the most destructive and common mite, the Cedar Mite, becomes very active and that volick oil was a good deterrent. I used the soap for the immediacy of contact and the Bayer for the systemic effect of six weeks. One of my trees had a very bronzey look on one side and there are some smaller areas on the others. A Bayer representative said that they don't believe that any damage could have been caused by that application. What say you? THANKS
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A: Cleve, I am not a trained chemical applicator, so I cannot answer that. However, Volck is a dormant oil and is used on conifers in late winter and very early spring when the plants are dormant. In hot sun it may burn the needles when used at dormant strength. Bayer 3 and 1 is a systemic that is taken up by the shrub, so it must be actively growing to be effective. I do not recommend playing chemist with pesticides, herbicides and other chemicals. The interior needles of arbs turn brown as they age and more so in fall. I never recommend mixing chemical unless they are listed on the label as safe to do so. I suggest you have a certified arborist do an onsite inspection and sort things out before you loose all your arbs. That damage looks severe on the one and the plant will probably not repair itself Good Luck and Happy Yardening, Nancy.