Evergreen tree diagnosis
we have 2 blue spruce trees and one deodora cypress in our yard. Last year they were full and healthy, we sprayed with a bugBgone as a preventative and spike fed for winter. This spring they are dropping needles to where they are almost bear. The Cypress only has some dead branches towards the bottom. We did a white paper test and there did not appear to be anything moving, just dead needles. The one blue spruce and cypress are near each other out back and the 2nd blue spruce is out front. I was only able to download 1 pic of the spruce out front however they are all the same.
New Castle County Delaware
Without seeing the trees and a sample from the trees, it is difficult to tell for sure. However, many evergreen trees were stressed by the winter cold and wind. I recommend you obtain confirmation that you have an insect problem before applying an insecticide. Some products will cause blue spruce to loose the nice blue color, due to the oil or carrier in the product. The product you mentioned may actually be a product recommended for turf grass application, so always be sure to read the label and apply the correct product for trees, shrubs, or turf.
Evergreen trees do not usually need as much fertilizer as deciduous trees might, and some fertilizer is taken up if you do fertilizer your lawn once a year in the fall. The root zone extends well out into the yard. The same can be said for lawn weed control products, they may be taken up in the drip zone of trees. Fertilizer spikes are limited in scope, as they deliver a sometimes high concentration to one very localized area. A soil test could help determine fertilizer needs.
I suggest giving your trees a bit of time to recover from the winter and begin to put out new growth. There are some fungal needlecast diseases of blue spruce. If they are still showing dieback, you could take a sample in to you local Extension Office, on Wyoming Road in Newark.
Thank you for contacting Cooperative Extension,