Shared from the 6/9/2018 Jamestown Sun Country eEdition. The pycnidia will push through the stoma, dislodging the stomatal plug, forming a white waxy cap on top the fruiting body. Chemicals labeled for use in the landscape against Rhizosphaera include: azoxystrobin,copper salts of fatty and/or rosin acids, copper hydroxide, copper hydroxide + mancozeb, mancozeb, thiophanate-methyl and phosphites. If disease pressure is high in the landscape, consider planting Norway spruce, which is less susceptible. Close examination of infected, dropped needles may show rows of shiny, raised, black fungal spots. For high value trees, dislodge and destroy fallen needles that collect in branch crotches and on the ground. New growth can be protected and the tips of branches will continue to grow and mask the older, defoliated stems and branches if the disease is detected early before branches have been killed. Consider an additional fungicide application if tree(s) begin producing new growth late in the season and environmental conditions are conducive for infection and disease development. Once needles are infected they cannot be healed or cured and will eventually fall off of the tree.
A lab test is the only way to determine the difference between the two different needle cast diseases. Colorado blue spruce (Picea pungens), white spruce (P. glauca) and Oriental spruce (P. orientalis) are the most severely affected, while Norway spruce (P. abies) and red spruce (P. rubens) are more resistant to the disease. | 2018 GARDENTECH, INC. All trademarks are the property of their respective owners. Drip irrigation or hand watering is preferable.
Use fungicidal sprays. Keep a close eye on existing trees. Its a slow moving disease that leads tobrowning and massive shedding of pine needles. Infected needles typically develop yellow or brown spots, and spring may also bring shades of purple or red. 3. With many fungal pathogens likeRhizosphaeraspp, removing infected tissue can help to slow the spread of disease. In Wisconsin, we have a large population of Colorado Blue Spruce trees. Optimal conditions are during excess moisture and humidity. From late spring to fall, rain splashes spores from diseased needles-on the tree and the ground-onto young healthy needles or to stressed older needles. Information on The Ohio State University laboratory can be found on theC. Wayne Ellett Plant and Pest Diagnostic Clinic website. Additionally, opportunistic stem cankering fungi and insect pests also contribute to disease severity by reducing host vigor. Fungicides may be effective in certain cases but will likely have little impact once the fungus is well established in the canopy. are during times of excess moisture and humidity. The first application should occur when the new needles are half elongated (50 percent elongation relative to previous years needle length). Treatment occurs when needles are half-elongated and again when fully elongated. When considering spruce trees; blue spruce is the most common and most susceptible host ofRhizosphaeraspp, followed by black hills spruce. Oil tools when done to inhibit rust. In many cases, even with aggressive cultural and chemical control, trees will only maintain their current appearance. SinceRhizosphaerasppprefers moist environments, it is important to prune. Avoid wetting needles watering the lawn. It most commonly affects Colorado Blue Spruce but can infect other Spruce species. Depending on environmental conditions (dry or hot weather) and infection timing, you may not always be able to find these structures or the needles bearing these structures may have been shed. When branches in the lower canopy decline or die, they should be pruned out to limit the establishment and spread of opportunistic pathogens. Contact information for each states diagnostic laboratory forU.S. residents. If you spot the disease early enough you may be able to prune away infected branches and reduce the spread of the fungus. True fir (Abies), especially white fir (A. concolor), can suffer severe damage as well. Spores require moisture to germinate and infect. Mature pycnidia appear as brown to black spherical structures that are less than 0.1mm in diameter (Figure 4). Rhizosphaera needlecast is caused by the fungus, Rhizosphaera kalkhoffii. We may be extremely busy answering calls, but leave a message and we will call back as soon as possible. Browning becomes general in late winter to early spring, and needles are prematurely shed during summer and fall, 12 to 15 months after initial infection. The disease is more destructive on spruces planted in shaded settings or in tight hedgerows. This is why accurate diagnosis is critical. Other conifers including pine, fir and cedar are rarely infected with Rhizosphaera. Similarities and differences between the two diseases exist. Additional hosts in New England include pine (Pinus), hemlock (Tsuga), Douglas-fir (Pseudotsuga), larch (Larix)and true cedar (Cedrus). A minimum of 3 years of treatment is recommended because of the organism's life cycle. The disease causes death and casting(dropping) of needles in Spruces. When trees are stressed, symptoms of infection may develop the same season. OurCertified Arboristswill advise which approach is suitable on a case-by-case basis. Schedule a consultation below. Can infect spruce, fir, cedar, and pine trees. The sooner we can analyze the condition of your trees, the better off your trees will be. Spray when the needles are half-elongated and again when fully elongated. One of the most common spruce tree diseases here is needle cast. Avoid planting highly susceptible species in low or shady areas where humidity and moisture remain high for prolonged periods of time. As a result, bare areas develop on the tree, reducing its ornamental value and overall health. On blue and white spruce, diseased needles often first appear purple, becoming brown to straw-colored over time. Rhizosphaeraneedle cast is the most common disease on spruce trees that is received in the Plant and Insect Diagnostic Clinic. It rarely kills the tree. This can also be helpful in large stands of trees that have grown into one another. Disease will spread within the tree from the bottom up and inside out (Joseph OBrien, USDA Forest Service, Bugwood.org);Figure 4. Rhizosphaera needle cast causes needles to turn brown, or in the case of the Colorado blue spruce, a purplish-brown, and fall from the tree prematurely (Figure 1). Infected needles drop between late spring and autumn, 12-15 months after infection. Proper diagnosis of needle cast is recommended before treatment is initiated, since other nondisease factors can cause similar symptoms. Prolonged wetness, especially in spring, is your spruces nightmare scenario! Branches may begin to die after 3-4 years of early needle loss. This promotes increased airflow, which is less favorable for infection and disease development. If the symptoms described above and in thepictures below are noticed, examine the affected area carefully.Rhizosphaeraspppicnidia(the fungal fruiting structures) are sometimes visible using a hand lens for magnification. If pycnidia are not present, test for disease by placing needles showing symptoms in a plastic bag with a wet paper towel. In these locations, air flow is limited, shade is more abundant and free moisture persistson needles longer. Avoid purchasing plants that look defoliated, discolored or wilted. Remove infected needles and branches during dry, sunny weather. Lets look at this tree disease in depth and how its treated here in the Milwaukee Wisconsin area. We have seven ISA certified arborists on our team and we work hard to stay trained and knowledgeable to make sure our customers get the best tree care services in SE Wisconsin. Of these sevenRhizosphaera species, the majority of spruce are infected by one particular species. Copyright 2022ISU Extension and Outreach Once the pathogen has become well established in/on the host, the specimen may need to be removed from the landscape. Please see our website forcurrent forms,fees,and instructions on collecting and packing samples. While fungicides are an option, there are several other ways to stay on top of this disease and keep your trees healthy. If spruce trees are dropping their needles, avoid using these trees in the landscape. You'll help prevent reinfections from cast leaves. Pycnidia in rows on needles infected with Rhizosphaera kalkhoffii (Edward L. Barnard, Florida Department of Agriculture and Consumer Services, Bugwood.org). They appear as asooty dust on the needles. At M&M Tree Care, well treat the tree for the fungus over the course of two years. If you have trouble accessing this page and need to request an alternate format, contact email@example.com. 2. Rhizosphaera needle cast symptoms on blue spruce tree (Minnesota Department of Natural Resources, Minnesota Department of Natural Resources, Bugwood.org);Figure 3. One common misunderstanding about this disease is that once needles become infected they can be cured. Some locations have an additional infection period between September and October and will require another treatment. Used with a hand-held, hose-end, or tank-style sprayer, Daconil Concentrate treats these needled evergreens easily and economically. Remember, spruce trees are not native to Iowa and at times the climate can lead to stress on an otherwise healthy tree. Needle cast has severely infected this spruce tree. Anyone considering treatment of their conifers or other trees can visit the Plant and Insect Diagnostic Clinic website at clinic.ipm.iastate.edu, to learn more about how to submit a sample to confirm the cause of a problem. Symptoms of both needle cast diseases look similar to each other. All Rights Reserved. If you have a Christmas tree plantation, randomly select 20 or more trees scattered throughout the plantation. While there are fungicides that help to manage this disease, the main use is in protecting new needles from the fungal pathogen. With patience, new needles can eventually help to fill in the bare patches caused by the disease initially. Clean up and dispose of fallen needles before spring growth begins. Connect with UMass Extension Landscape, Nursery and Urban Forestry Program: Civil Rights and Non-Discrimination Information, UMass Research and Education Center Farms, Soil and Plant Nutrient Testing Laboratory, Water Testing / Environmental Analysis Laboratory, Conservation Assessment Prioritization System (CAPS), Extension Risk Management/Crop Insurance Education, North American Aquatic Connectivity Collaborative, Agriculture & Commercial Horticulture Resources. Helping Ohio's green industry identify and manage diseases of ornamental plants, Botryosphaeria Canker and Dieback of Juniper, Pestalotiopsis Tip Blight and Dieback of Conifers, C. Wayne Ellett Plant and Pest Diagnostic Clinic, Greenhouse Industry Roundtable of the Midwest. Burn or remove the collected debris. Prune out diseased branches and rake up fallen needles. Keep weeds and other vegetation from encroaching around the base of trees to encourage air circulation among and light penetration to the lower branches. Share this post! A minimum of two years of treatment is recommended because of the organism's life cycle. Water in summer and fertilize in the spring to keep trees growing vigorously and prevent needle cast. Extension Agent, Agriculture & Natural Resources, NDSU Extension, Stutsman County. For more information on our services or to schedule an appointment, contact us today: Know someone who would benefit from this info? Rhizosphaera kalkhoffiioverwinters in infected needles, on the tree or ground and are released from the infected needles in the spring. Since 1968 M&M Tree Care has been providing local professional tree care services to the metro Milwaukee area. Use a hand lens to observe pycnidia, which appear as tiny, black spots arranged in neat rows on infected needles. Needles can turn brown and then black as the fungus takes over the needle. Conduct regular soil and plant tissue analysis tests to determine if plants require supplemental nutrients. Symptoms ofstigminaneedle cast are almost identical to those ofrhizosphaeraneedle cast. Avoid pruning, shearing, and/or other operations that would facilitate spore dispersal and infection during wet periods. In severe cases, the disease can kill entire trees. Purchase pest and pathogen-free stock from reputable sources. Picnidiacan be seen as small black specks that will appear in the stomata of each individual needle. Prune out diseased branches and rake up fallen needles. Identifying the fungal fruiting bodies in the stomata should be identified before treating a tree with fungicide. One option for management of this disease is to simply not plant susceptible trees. This field is for validation purposes and should be left unchanged. 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World rights reserved. 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.
Branches lower to the ground are more commonly affected with the disease traveling upwards and outwards in conditions are favorable. Even though they're called evergreens, trees such as pine, Douglas fir, and spruce naturally lose some of their needled leaves each year. Spruce trees are not able to form new needles where the old ones dropped. The symptoms of Rhizosphaera Needle Cast are most easily spotted in late autumn through winter and include: The disease typically starts at the base of the tree on inner branches and works its way up as it progresses. Maintain open spacing when planting or by mowing grass or brush. Proper plant spacing will minimize moisture retention on the plant surface and will decrease the likelihood of disease development. It is also helpful to prune while the plant is dormant and during dry conditions. Inspect trees, especially 5 to 10 year olds, for brown needles in spring. Left untreated, a severe case of needle cast can lead to continual thinning and decline of the tree. When needle length of the new growth is roughly half the size of old growth, the first spray should be applied. Fungicides should be applied in the spring when new growth is 1/2 inch longand then againon regular intervals should wet weather persist. Pycnidia, the fungal fruiting bodies containing spores, begin forming in rows on infected needles during spring when moisture is high. If your sample is from outside of Iowa please do not submit it to thePlant & Insect Diagnostic Clinic without contacting us. This genus also infects several conifer species including; fir, cedar, spruce, and pine. If the pathogen is present, pycnidia should develop in a day or two. Improve air circulation to allow needles to dry more quickly. Read each fungicide label thoroughly for safety precautions and information on how to prepare, apply, store, and dispose of the product. Infections take place in the spring, and symptoms show up about a year later. Organic Materials Review Institute (OMRI), Purplish cast of needles on Colorado blue spruce (, Possible rhizosphaera needlecast disease on Colorado spruce (. In late summer, needles yellow, then turn purple-brown, dropping by late autumn. Severely infected needles turn black due to the sheer number of pycnidia. Infected 2-year old needles become spotted or mottled, some turning yellow and some developing a purplish brown color in late summer. It should be kept in mind that infections can take place anytime during the growing season when environmental conditions allow. Eventually new needles will replace the old, diseased needles. Needle cast diseases can be effectively controlled with fungicides containing chlorothalonil (Bravo is one example). These structures form in pore-like openings of the needle called stomata (singular=stoma). Rhizosphaeraneedle cast is caused by fungal pathogens within the genusRhizosphaera. Avoid overhead watering.Water on the foliage can promote infection. 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. Rhizosphaera needle cast is caused by the fungus, Rhizosphaera kalkhoffii. This disease is caused by a fungus (Rhizosphaera kalkhoffii) infecting only spruce trees. Needlecast Identification/Symptoms: Needlecast symptoms vary depending on the type of tree and the specific fungi involved. IPM incorporates a wide range of strategies to prevent, minimize, and/or control abiotic and biotic diseases and pests. 2022 University of Massachusetts Amherst Site Policies, Center for Agriculture, Food,andtheEnvironment, UMassExtension Landscape, Nursery and UrbanForestry Program, CenterforAgriculture, Food, and theEnvironment, Center for Agriculture, Food and the Environment. Otherwise, do not fertilize woody plants. Disinfect pruning tools between cuts by dipping in a 10% chlorine bleach solution. The spores can linger on susceptible needles for several weeks until environmental conditions become favorable for germination and invasion. Always read product labels thoroughly and follow instructions, including guidelines for treatable plants, application rates, and frequencies. Protect your garden against diseases including rust, leaf spots, blights, mildew, and fruit rots with Ortho MAX Garden Disease Control Concentrate. The cycle begins anew the next spring, Spores infect leaves that are wet for at least 48 hours, so they are worse during wet springs. If half the branches have fruiting bodies on at least 10% of the needles, consider treating the entire plantation in spring and summer. Integrated pest management (IPM) is an approach to plant health care and disease and pest control. Pycnidia (small, black-colored fruiting bodies of the fungus through 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. This symptom gives the disease its name needle cast. Keep in mind, there is a look a-like disease calledstigminaneedle cast. Two needle cast diseases occur in North Dakota: Rhizosphaera needle cast and Stigmina needle cast. This article was originally published on . The first application should occur just after bud break, when new needles are half elongated relative to the previous years needle length. (800) 262-3804, Iowa State University|PoliciesState & National Extension Partners, Like us at Plant and Insect Diagnostic Clinic, Like us at Department of Plant Pathology and Microbiology, Contact information for each states diagnostic laboratory forU.S. residents, collecting samples for suspected rhizosphaera needle cast, Diagnosis of Spruce Problems Requires Good Samples, Plant and Insect Diagnostic Clinic Update April 21, 2017. Since spores of the fungus are spread by wind and rain splash, removing the infected tissue can reduce this spread. Needles of any age and on any part of the tree may be infected, but the disease often starts on 1 year or older needles on the lower branches of the tree, attacking several branches at one time (Figure 2). Spores are dispersed by wind and splashing rainwater and infect newly emerging needles with a soft cuticle as well as mature needles. When the weather is warm and humid, it is particularly easy for Rhizosphaera Needle Cast to spread. Treatment for Rhizosphaera needle cast is two properlytimed applications of chlorothalonil per year for at least two consecutive years, and sometimes three years, is required for control. A general rule of thumb is typically around Memorial Day. Needle cast symptoms can also be caused by pests, such as the pine needle scale or the spruce spider mite, or an abiotic stress to the tree, such as drought. Optimal temperature for fungal development on wet foliage is 77 F. Infection will occur in 48 hours if spores are present. Once the needles are infected, symptoms may take 12 months or longer to become visible. Mild temperatures and prolonged needle wetness favor disease development. Wind and water spread needlecast-spawning fungi. In the Northeast and Northcentral states, start spraying for Lophodermium needlecast in mid-July and early August. The content of this site is published by the site owner(s) and is not a statement of advice, opinion, or information pertaining to The Ohio State University. Lower branches are commonly affected because the foliage is denser and shaded, receiving less air flow and holding moisture for longer periods of time compared to higher branches. The disease causes death and casting (dropping) of needles in spruces, especially Colorado spruce and occasionally white spruce. When all other management is not enough, fungicides can be used to help managerhizosphaeraneedle cast. Spray to cover all needle and branch surfaces until thoroughly wet. Always rake and dispose of needles that fall to the ground. Spores require moisture to germinate and infect. The second application should occur 3 to 4 weeks after initial application. Avoid planting young trees near old trees that may be harboring pathogens. It can be hard to catch early because signs of infection may not manifest until the following year when new growth develops. When purchasing plants from a nursery, inspect for signs and symptoms of disease. A second spray should then be applied 3-4 weeks later. Pruning can also help increase airflow to reduce the amount of humidity held inside the trees canopy. All management decisions should be carried out based upon the specific requirements of the plant. Once treatments begin, reapply Daconil fungicide every three to four weeks until dry weather stabilizes. Beginning in the spring and lasting through the autumn season, spores are dispersed from infected needles by wind and splashing rainwater. The second application should occur two to three weeks after the first application. Begin needlecast treatments in spring when new needles are 1/22 inches long. Ireceive several calls asking about what is wrong with older spruce trees. In order for disease to occur three things need to happen; the pathogen needs to be present, the environment needs to be conducive for disease development and there needs to be a host that is susceptible to disease. GardenTech is a registered trademark of Gulfstream Home and Garden, Inc. Daconil is a registered trademark of GB Biosciences Corp. USDA Forest Service, Northern and Intermountain Region, USDA Forest Service, Bugwood.org (CC BY 3.0 US), USDA Forest Service - Ogden, USDA Forest Service, Bugwood.org(CC BY 3.0 US), Joseph O'Brien, USDA Forest Service, Bugwood.org (CC BY 3.0 US), Photo credit: USDA Forest Service, USDA Forest Service, Bugwood.org (CC BY 3.0 US), Terry S. Price, Georgia Forestry Commission, Bugwood.org (CC BY 3.0 US), Frantisek Soukup, Bugwood.org (CC BY 3.0 US). 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 kalkhoffii overwinters in infected needles on the tree or ground.
During the spring, well spray the tree with a copper-containing fungicide designed to keep the rhizosphaera fungus from spreading.
Infected needles become spotted, some turning yellow and some brown. Manyspruces used as landscape ornamentals are shade intolerant and prefer full sun with no surrounding plants to thrive. Remember to always follow the instructions on product labeling. M&M Tree Care|Website by New Sky. For more information, readProper fungicide use. 5. When the disease becomes well established in the lower canopy of a tree, Rhizosphaera then spreads upward in successive years, gradually leading to increased rates of premature needle shedding. We can have one of our certified arborists come out to your home and assess your trees. Manage by aiming to reduce spread to healthy tissues. Of the fungicides mentioned in Strategy 5, consult the Organic Materials Review Institute (OMRI) for appropriate organic copper products. Measure the recommended concentrate amount with the convenient measuring cap. It may be more prudent to replace severely diseased blue spruce with new trees or shrubs. Plan for the mature size of the tree(s) when spacing plants, or plan to remove trees as they begin to intermingle lower branches. Only the newest, current year's growth stays green, as needles on branches become sparse and thin. Needle Cast on Spruce trees is generally first evident on the innermost needles in the lower canopy. 1. Needles on interior branches in thelower canopyare most commonly infected first. It attacks more mature needles first. Once the needles are infected, symptoms may take 12 months or longer to become visible. Within a few years after treatment, an infested spruce tree can start to produce healthy new needle growth again. The fungus grows within the needles for almost a year with no symptoms; then needles turn yellow or purple-brown and die. Crowded, wet conditions promote these diseases. Prevention is the first line of defense against Rhizosphaeraneedle cast. about Ortho MAX Garden Disease Control Concentrate, Ortho BugClear Insect Killer for Lawns & Landscapes Ready-to-Spray, Ortho Home Defense Max Indoor Insect Barrier with Extended Reach Comfort Wand, Ortho MAX Garden Disease Control Concentrate, Ortho GroundClear Super Weed & Grass Killer1, Ortho WeedClear Lawn Weed Killer Ready-to-Use with Comfort Wand. Disease symptoms include a browning or purpling of needles, which eventually drop from the tree leaving bare patches.