Sherie, 

I would double check that is is needle cast. Needle cast is not a common disease in Colorado compared to other states. That said, yes you would want to treat before the fungus is active as most fungicides are not systemic (including the one you listed). If you wanted to email me some images we could go from there. 

Thanks,  

This doesn't look consistent with needle cast to me. However if you'd like to have it tested you can send it to the CSU Lab: https://plantclinic.agsci.colostate.edu/submit-a-sample-2/. 

Dieback on the needles like you're seeing can have a host of causes from salts, cold, watering practices, to poor planting. How is the tree planted? Do the branches come out at the ground level? That would indicate the tree is planted deep which can be problematic for tree health. Depending on where you live, you may have salty water (if you're out in eastern Adams County this is likely, if you're in a city like Thornton, Westminster, it's less likely.) Finally, last spring and this spring we had pretty intense April freezes just as our conifers (spruce in particular) were coming out of winter dormancy. This could have impacted negatively the health of your trees. 

The amount of growth even in previous years is indicative to me that the tree is either stressed or newly planted. 

I did forget to ask, are they newly planted or well established? Approximate size? 

Thanks, 

~Cassey 

Hi Sherie, 

 So to a certain extent older needles (3-5 years old) will naturally diminish and fall off. Generally once the growth has developed to the point where older needles are shaded they don't perform as effectively and can become an energy sink rather than an energy source. 

That said, with your water source it's definitely likely that salts are a problem. Spruce are particularly prone to issues with salts and unfortunately I don't have a good solution to offer you. Treating with a fungicide will not do anything if the problem is abiotic, and may put the tree under additional stress. 

Good cultural care is your best bet: water reliably 10-15 gallons as the soil begins to dry out per caliper inch (trunk diameter). So if the trees are around 5" you'd be looking at putting down around 50 gallons each time the soils dries out, preferably around the dripline of the tree. 

If the trees are a long distance from any fertilized turf you could feed lightly, but on the surface. Most tree roots collect water and nutrients from the surface and so really are not that deep in the soil (12-18" deep on average) so deep root feeding is putting nutrients where the tree does not need them. The plant also is not picky whether you use an organic or an inorganic form of fertilizer. 

The "local" tree experts that I know of are here in the Extension office or arborists (www.isa-arbor.com "Find an arborist"). Otherwise the Plant Diagnostic lab I referenced earlier. I will say that we've had a LOT of calls about spruce looking poorly this year, and almost across the board it's due to environmental conditions. The best recommendation we have is to improve cultural conditions to the best you can. 

I hope that helps!