Rhizosphaera Needle Cast and Swiss Needle Cast
Once Needle Cast is diagnosed, the treatments must be consistently applied at the right time for at least 3 years in a row to prevent new infections and allow new growth to cover areas where needles are lost. After 3 years of treatment the trees should be inspected to determine if treatment needs to continue.
The disease cycle can be reduced by removing infected branches, cleaning up and destroying the fallen needles, pruning other trees to improve air movement around the infected trees and by not allowing irrigation water to contact the foliage. If all the needles can not be cleaned up and destroyed, applying 4″ of mulch over the needles will reduce the amount of spores that can splash up and cause future infections.