(Megan Kennelly, KSU Plant Pathology)
Which of these is a disease, and which is natural needle drop?
If you guessed natural needle drop for the first and disease (Dothistroma needle blight) for the second, you are right!
If you were not sure, here are some resources to figure it out.
In a recent article in Horticulture News, Ward Upham mentioned some recent reports about natural needle drop on evergreens. You can read more about it here:
http://www.ksuhortnewsletter.org/newsletters/natural-needle-drop-on-spruce-arborvitae-and-pines
In addition, this publication talks about pine diseases and at the end there is a section about natural needle drop:
https://www.bookstore.ksre.ksu.edu/pubs/l722.pdf
If you see yellowing, browning, or dropping of needles and you still are not sure you can reach out to your local K-State Research and Extension office or contact the KSU Plant Disease Diagnostic Lab:
Plant Disease Diagnostic Lab
1712 Claflin Road
4032 Throckmorton PSC
Manhattan, Kansas 66506
(785) 532-5810
Fax: (785) 532 5692
clinic@ksu.edu