Infections usually start in the spring or early summer and can change the color of the foliage to a variety of hues.

[1] Rhabdocline pseudotsugae, known as needle cast, is a fungal pathogen that affects Douglas Fir specifically in the Pacific Northwest and Intermountain provinces.

The bands start yellow but turn brown/red and can become purple with spots on the upper or lower surface of the needle.

[2] New infections start in the spring or early summer and conditions that cause prolonged needle wetness promote heavier outbreaks.

[4] The first symptoms produced are small yellow spots on the needle ends that develop in late summer or fall.

[5] The fungus Rhabdocline pseudotsugae have apothecia that are normally first produced on the under side of the needles, but it's not uncommon to find them on the top surface too.

They are first produced as rounded cushions and as the epidermal layer ruptures, a brown elongated disc is exposed.

Needle drop occurs after the ascospores are discharged, normally resulting in only a one-year life span for the fungus.

It is important not to prune when foliage is wet and to sterilize tools by dipping in denatured alcohol for 3 minutes after shearing infected plantations.

Douglas-Fir also require full sun and if planted in a shaded area it can encourage needle blight development.