Promote good air circulation and encourage rapid drying of foliage by mowing weeds or other vegetation near trees. Spraying too early or too late will miss the stages when the tree can be protected from infection by the fungus. Infected 2-year old needles become spotted or mottled, some turning yellow and some developing a purplish brown color in late summer. Purplish cast of needles on Colorado blue spruce Picea pungens caused by rhizosphaera needlecast. In situations where planting susceptible spruce trees is unavoidable, going out of the way to maintain plant health can be a step in the right direction. Note, characteristic purplish brown color of the needles Possible rhizosphaera needlecast disease on Colorado spruce Picea pungens.
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. Needle cast diseases of spruce are treatable. If unsure whether a spruce has a needle cast disease, consider consulting with your local county agent. List of Products registered in Canada for use against needle diseases of spruce in general or specifically for Stigmina or Rhizosphaera. Rhizosphaera Needle Cast Encyclopedia Article. Management Conifers vary in their susceptibility to the disease, so if disease pressure in the landscape is high, choose resistant trees such as Norway spruce for new plantings if spruce is desired. Repeated infections will cause trees to begin having a sparse looking interior and after years of severe infection, branches may begin to die. Chemicals labeled for use in the landscape against Rhizosphaera include:
Fungicides may be effective in certain cases but will likely have little impact once the fungus is well established in the canopy. On spruce, the pycnidia are present on all sides of the needle, whereas on fir, they occur only on the underside of the needle. Left untreated, a severe case of needle cast can lead to continual thinning and eventual decline of the affected tree if spring weather is conducive to infection year after year.
In situation where spruce is the tree of choice, try to avoid blue spruce and take a look at Norway spruce as an alternative. 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. List of Products registered in Canada for use against needle diseases of spruce in general or specifically for Stigmina or Rhizosphaera. It is also helpful to prune while the plant is dormant and during dry conditions.
The disease is more destructive on spruces planted in shaded settings or in tight hedgerows. Norway spruce would be a less susceptible tree. Rhizosphaera needle cast and Stigmina needle cast.
When needle length of the new growth is roughly half the size of old growth, the first spray should be applied. Once needles are infected they cannot be healed or cured and will eventually fall off of the tree.
Needle cast diseases thrive in humid, wet environments and they are more common in the north and east parts of our state. Sclerotinia Risk in Canola. High powered magnification is required to differentiate between the two.
Needles of Colorado blue spruce Picea pungens dropping due to rhizosphaera needlecast disease. Rhizosphaera needlecast is a fungal disease affecting mainly Colorado spruce, and occasionally other spruce. Rhizosphaera needle cast caused by the fungus Rhizosphaera kalkhoffii primarily infects Colorado blue spruce, while Stigmina needle cast caused by the fungus Stigmina lautii affects both blue spruce and Black Hills spruce.
Conifers vary in their susceptibility to the disease, so if disease pressure in the landscape is high, choose resistant trees such as Norway spruce for new plantings if spruce is desired. Of these nine Rhizosphaera species, the majority of spruce are needlee by one particular species. Rhizospahera pathogen invades susceptible needles through the stomata pores used for gas exchange and overwinters in diseased needles that have fallen to the ground or those that remain in the canopy.
If needke whether a spruce has a needle cast disease, casr consulting with your local county agent. You are here Home. Sign up for our e-newsletter. Needle cast diseases of spruce are treatable. Maintain open spacing when planting or by mowing grass or brush. Environmental stresses such as drought, deep planting and mechanical root injury contribute to disease severity.
A lot of time and money has been wasted by applying fungicides at the wrong time. Chemical controls registered for Rhizosphaera needlecast control include fungicides containing chlorothalonil.
Needle Cast Diseases of Spruce: Diagnosis and Treatment (6/2/11) — Crop & Pest Report
These other causes can be easily confused with a needle cast disease. Infection begins in spring, in April or May. While funyicide are an option, there are several other ways to stay on top of this disease and keep your trees healthy. Symptoms of both needle cast diseases look similar to each other.
Both Stigmina and Rhizosphaera produce similar symptoms and close examination with a magnifying lens is needed to determine positively which fungus is present. Spores are dispersed by splashing and dripping water. Prolonged wetness can induce extensive infection.
Province of Manitoba | agriculture – Needlecast Disease of Spruce
When trees are stressed, symptoms of infection may develop the same season. Spruce trees often thrive in North Dakota under the right conditions. Symptoms and Diagnosis Infections take place in the spring, and symptoms show up about a year later. Pycnidia small, black-colored fruiting bodies of the fungus fungicde which spores are discharged develop on the surface of infected needles and can be observed with the naked eye or a 10X hand lens during almost any season.
True fir Abiesespecially white fir A. This dungicide, cool spring temperatures and wet conditions favor development of needle cast diseases on spruce.
Needle disease can be a significant problem in Christmas tree plantations, where it can greatly reduce the attractiveness and the value of the fungickde, but can be a concern in shelterbelts and urban landscapes as well.
It rarely kills the tree. Anyone considering treatment of their conifers or other trees can visit the Plant and Insect Diagnostic Clinic website at clinic.
The fruiting bodies can be observed on needles that are still green, needles that are in process of discolouring or dead needles. Additionally, opportunistic stem cankering fungi and insect pests also contribute to disease severity by reducing host vigor.
Rhizosphaera Needle Cast
Needles of Colorado blue spruce Picea pungens dropping due to needoe needlecast disease Rhizosphaera needlecast is caused by the fungus, Rhizosphaera kalkhoffii. Black fruiting bodies are visible on discolored needles and even some green ones.
rhizospnaera Scouting for Disease Keep a close eye on existing trees. After several successive seasons of needle loss, affected trees are severely weakened and the tree may die.
This can also be helpful in large stands of trees that have grown into one another. This is why accurate diagnosis is critical. Fruit Gardening Vegetable Gardening. Purplish cast of needles neecle Colorado blue spruce Picea pungens caused by rhizosphaera needlecast Possible rhizosphaera needlecast disease on Colorado spruce Picea pungens. Feel free to use and share this content, but please do so under the conditions of our Creative Commons license and our Rules for Use.
Two needle cast diseases occur in North Dakota: