Fungal disease, Rhizospaera needlecast on Blue Spruces

Asked May 16, 2016, 3:30 PM EDT

Could you please confirm my blue spruce in the attached picture has Fungal disease, Rhizospaera needlecast? After much research, that is my conclusion. I understand Needle cast diseases can be effectively controlled with fungicides containing chlorothalonil and the for Rhizosphaera needle cast, two properly-timed applications per year for at least two consecutive years, and sometimes three years, is required for control. The first application should occur when the new needles are half elongated (50% elongation relative to previous years’ needle length). They usually say “around Memorial Day”, but actual timing depends on the year, the location, and the individual tree. The second application should occur three to four weeks after the first application. The timing of the two applications is the same for the second and third year. Timing of treatment for Stigmina needle cast is similar, except preliminary data suggest that the trees should be treated indefinitely, with at least two properly timed fungicide applications per year. Proper timing of the fungicide application is critical for effective control. Spraying too early or too late will miss the stages when the tree can be protected from infection by the fungus. A lot of time and money has been wasted by applying fungicides at the wrong time. Can you help me with when the proper timing is to spray in the Deep Creek Lake area of Oakland, MD? Name, age and/or size of plant Blue Spruce, 10+ years old, 30 feet (see pic) When was the problem was first noted 2-3 years ago What part of the plant is affected? Lower branches Have symptoms progressed or changed? Slowly moving up the tree Growing conditions (full sun, part shade, shade, windy, salt spray, etc.) full sun, moist soil Soil problems (compacted soil, construction activity, poor drainage) No Pesticide and fertilizer applications Sprayed w/a fungicide containing chlorothalonil in the middle of last summer w/no affect--now know timing really matters

Garrett County Maryland blue spruce trees needlecast disease

1 Response

We cannot confirm a needle cast disease from your photos. We recommend that you take a sample to your local extension for confirmation.
Contact MG Coordinator: Ashley Bachtel-Bodkins, (301) 334-6960

In general your blue spruce looks thin. Even if you spray, additional branches will not fill in and the tree may not look much better. All you can do is preserve what you have and it will be difficult to spray a tree that high. These trees can also be susceptible to cytospora canker and there are no chemical controls.