Phosphorous acid?

[arborcareidaho]

Anyone have experience/success using phosphorous acid fungicide treatments. Agrifos or other products?

Looking for a good treatment for a bad case of Diplodia(tip blight) in a very large ponderosa pine (too tall to spray)...

 

[macrocarpa]

Is agrifos labeled for diplodia? From my research it seems no one is quite sure what all phosphorous acid will consistently provide control for/learning process. But the application options sure make it appealing (trunk spray, soil injection).