This is why it is important to maintain plant vigor. Slow release nitrogen fertilizers should be used in the spring. Avoid excess fertilization during summer months. Seventy-five percent of the season's nitrogen should be applied in the fall. Also, it is time to core aerate, which is most effective during the spring or fall rather than the summer.
Timing is essential for effective control.
F at a depth of 2 inches, usually late April or early May. Evergreens Winter injury and disease can look similar. Inspect trees carefully for little black pimples on needles, resin flowing from the trunk or branches, or whole branches dying back. Pine wilt, a disease caused by a complex of organisms, has lately become an important problem in Iowa. Dead pines can harbor organisms involved in this disease. Remove and dispose of any pines diagnosed with pine wilt.