WSU Extension

Hortsense

Spruce
 
Disease
Oil discoloration of foliage 
Rhizosphaera needle cast 
Rust 
Insect
Coneworms 
Cooley spruce gall adelgid 
Douglas fir tussock moth 
Pine needle scale 
Spruce aphid 
Spruce bud scale 
Spruce budworm 
Spruce needleminer 
Spruce spider mite 
White pine weevil 



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Caption: Spruce Rhizosphaera needle cast
Photo by: R.S. Byther
  
Spruce : Rhizosphaera needle cast
(revision date: 4/11/2018)


Biology
The first symptoms occur in late summer, when a yellow mottling develops on the current season's needles. During the fall to early spring, the infected needles turn brown or purplish brown. The needles are usually dropped later that spring or in the following summer. Tiny black fruiting bodies are formed in rows on the underside of the affected needles in the spring and occasionally at other times. This disease can cause severe needle loss.
Management Options


Non-Chemical Management
  • Remove and destroy all fallen needles from in and under the tree. Do not compost diseased plant material.
  • Avoid overhead irrigation.
  • Provide good air circulation in plantings. Avoid shading or crowding trees.
Select non-chemical management options as your first choice!

Chemical Management

Begin applying when new shoots are 0.5 to 1.5 inches long. Continue at 3- to 4-week intervals if weather remains very wet. Horticultural oils, soap-based products and some other products may cause discoloration of spruce needles, particularly on Colorado blue spruce. Read labels carefully and test on a small area before application. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • GardenTech Daconil Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 67572-82-71004
  • Ortho Max Garden Disease Control Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 239-2522
  • This list may not include all products registered for this use.
Images

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Caption: Spruce Rhizosphaera needle cast
Photo by: R.S. Byther
Caption: Spruce Rhizosphaera needle cast
Photo by: R.S. Byther