On May 31 I have 19 trees planted , about 2 weeks ago realized trees started to get brown leaves, checked for mites and paper showed we had them also has some webbing, sprayed after sun went down with solutions given to me at garden store, trees I I feel look worse?
For spider mites on arborvitae, use insecticidal soap, or Neem oil. Follow instructions. Home Depot/Lowes will have one or both of those. For several big trees see if you can find the concentrate that you dilute down for spraying in a hose end sprayer.