FUNGICIDE FOR SPRUCE NEEDLE CAST
Young and old needles are equally susceptible, but due to tree growth patterns new needles appear green and healthy while older needles will show more advanced stages of symptoms. Symptoms progress over the course of 3 years, leading to needle discoloration and severe thinning of foliage on the lower two-thirds of trees. If trees are severely infected, the lower whorl of branches may also be removed to help increase air circulation. The first indications of disease appear as tiny black spots sporodochia on stomatal pits along with faint yellow bands around the needles. Rhizosphaera needle cast may be controlled in one year if fungicides are applied correctly. Management of stigmina needle cast In areas where stigmina needle cast is prevalent, the most effective management tactic is tree selection. Another key characteristic of needle cast is the microscopic rows of small black dots fungal fruiting bodies that displace the normally white stomata along the length of the underside of needles.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. Rhizosphaera needle cast on blue spruce. This material may be available in alternative formats. Early season nursery crop disease management. Therefore, if you put your first spray on the trees May 15 and a second spray on May 25, we ask you to consider spraying June 15 four weeks after the first spray to ensure your coverage is complete. The information contained within may not be the most current and accurate depending on when it is accessed.
Proper diagnosis of needle cast is recommended before treatment is initiated, since other non-disease factors can cause similar symptoms.
March 26, – Author: Frost-covered plants caught on video. Needle disease can be a significant problem in Christmas tree plantations, where it can greatly reduce the attractiveness and the value of the trees, but can be a concern in shelterbelts and urban landscapes as well.
As the disease continues, trees become unsightly and lose their value as a visual screen or privacy fence. You are here Home.
When Should I Spray Conifers for Needle Diseases? | Horticulture and Home Pest News
Other evergreen options include concolor white fir, Easter red cedars or other junipers, and yew. It could be that you have not completely managed Rhizosphaera. Other pests and environmental problems can cause browning and death of older needles, including normal needle death that occurs simply as a function of needle age or shading. Austrian pines are susceptible to two fungal needle diseases, Diplodia tip blight and Dothistroma needle blight.
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. Use of fungicides is possible, but may only be sensible for larger-scale growers such as nurseries and Christmas tree farms.
To have a digest of information delivered straight to your email inbox, visit http: In other words, when the needles stay wet there is a greater chance of Stigmina infecting the needles. Don’t apply fungicides unless you are certain your tree has a fungal needle disease. Needles with signs evidence of the pathogen.
Diplodia tip blight causes new growth to appear as tufts of stunted, brown needles on the tips of branches. Further magnification would be necessary to determine whether the fungus is Stigmina or Rhizosphaera. Labeled fungicides include products containing the active ingredients azoxystrobin, chlorothalonil, copper hydroxide, copper salts of fatty and resin acids, copper sulfate, mancozeb, mono- and di-potassium salts of phosphoric acid, pyraclostrobin, sulfur, and thiophanate-methyl.
Examine the white rows of stomata on two-year-old needles and if half of the branches have dark fruiting bodies on more than 10 percent of the needles, consider treating the entire plantation. Spruce trees grow best in moderately moist, well-drained soils but can be planted in other soils if adequate moisture is available.
Stigmina Needle Cast
For Rhizosphaeria of spruce, randomly select 20 or more trees scattered around the plantation, and remove three sample branches from each tree. Spraying too early or cxst late will miss the stages when the tree can be protected from infection by the fungus.
Dothistroma needle blight causes spots to appear on the needles, which turn brown above the spots.

Two needle cast needlee occur in North Dakota: The fruiting bodies can be observed on needles that are still green, needles that are in process of discolouring or dead needles. If you still have needle-casting problems even though you have been using chlorothalonil-based fungicides, we ask you to consider spraying for needle casting disease management again, one month after your first spray.
Needle Cast Diseases of Spruce: Diagnosis and Treatment (6/2/11) — Crop & Pest Report
Avoid planting susceptible spruce trees. Fungidide a few years after treatment, an infested spruce tree can look beautiful again. Needle cast diseases can be effectively controlled with fungicides epruce chlorothalonil. In the urban setting, needle casts are more of an endemic, as most conifers are ill-suited to the Midwest urban environment.
Wpruce epidemics of needle casts or rusts are not uncommon, and develop under periods of extended leaf wetness. Find your county office. The fungal fruiting structures emerge on these needles and are usually large enough to be visible to the eye, with the fruiting structures appearing as rows of small dots running lengthwise along the white bands of the needles.
Needle casting disease of spruce is currently managed with fungicides after the new growth has expanded to 0.

Microscopic observation spruxe required to distinguish both diseases from each other. Stressed trees should also be mulched and fertilized as needed. List of Products registered in Canada fungicdie use against needle diseases of spruce in general or specifically for Stigmina or Rhizosphaera. Symptoms of both needle cast diseases look similar to each other.
Check the label of any pesticide referenced to ensure your use is included. For effective control, infected trees should be treated once in mid-May and again four to six weeks later. Several fungal needle diseases of conifers require fungicide sprays for satisfactory control.
As the disease progresses, severely infected branches die, leaving the tree with a hollow or thin appearance Fig. Dothistroma needle blight on Austrian neddle. Immature sporodochia, which are fungal fruiting bodies, develop on needles by late spring and overwinter.
Note that trees that are infected with both diseases require a total of four sprays.
To determine if your trees warrant chemical management, look for signs srpuce fungal fruiting bodies on the needles. These other causes can be easily confused with a needle cast disease. A lot of time fhngicide money has been wasted by applying fungicides at the wrong time. The fruiting bodies of Rhizosphaera kalkhoffii are spherical Figure 2 while those of Stigmina lautii have what look like microscopic hairy projections emerging from a the fruiting body Figure 3.
