To manage it, remove infected trees, sanitize tools, control weeds and plant trees with adequate spacing to allow for good air circulation. There are no effective fungicide controls for this disease. A third treatment may be necessary if the infection is severe.Īnother fungal disease, Lirula needle blight, is most prevalent in white spruce. Spray the tree in the spring and then repeat 14-21 days later. Severe infections can be treated with a fungicide. Apply a 3-inch (7.5 cm.) layer of mulch around the base of the tree. Water only at the base of the tree and avoid getting the needles wet. The discolored needles fall of in the middle of summer, leaving the tree looking barren and thin.Īs with other fungal diseases, cultural practices can prevent the disease. As the disease progresses, the infected needles turn brown to purple and progress up through the tree. Needles at the tips of the tree remain green while older needles near the trunk become discolored. Needlecast is most common on Colorado blue spruce, but it does infect all spruces. It affects spruce trees growing outside their native region and starts on the inner and lower growth. Additional Reason for Needles Turning ColorĪnother reason for brown conifer needles may be the fungal disease Rhizosphaera kalkhoffii, also called Rhizosphaera needlecast. In some cases, conifers changing color in autumn is normal as they shed older needles in place of new. Also, mulch around the conifers to prevent deep freezing, making sure to keep the mulch about 6 inches (15 cm.) away from the trunk of the tree. Be sure to water young trees regularly in the fall and winter when the soil is not frozen. In the future, to prevent browning conifer needles due to winter drying, choose trees that are hardy to your area, plant in well-draining soil and in an area protected from winds. Less often, the damage is severe and branch tips or entire branches may be lost. In this case, the damage is generally minor and the tree will recover and push out new growth. Normally, when winter damage is to blame for discolored needles, the base of the needles and some other needles will remain green. This results in needles that are changing color. Usually, it’s nothing the tree can’t handle, but sometimes during the late winter to early spring when the root system is still frozen, warm, dry winds exacerbate water loss. Conifers transpire through their needles during the winter, which results in water loss. Needles turning color may be the result of environmental conditions, disease or insects.Ī common culprit is winter drying. There are numerous reasons for discolored needles. Why are the needles turning color? Can anything be done to treat browning conifer needles? Help, My Tree’s Needles are Changing Color! The previously healthy tree is now draped in discolored, brown conifer needles. Severely defoliated trees can lose nearly all of their >1-year-old needles, but associated tree mortality is rare.Sometimes conifer trees will be looking green and healthy and then the next thing you know the needles are changing color. Red-brown foliage discoloration and premature needle shed symptoms become apparent in late summer and fall, 1.5 years after infection. In spring (and summer if conditions are suitable), primarily infecting new needles. Spores are rain-splash dispersed from fruiting bodies Rhizosphaera: Small black fruiting structures occupy pores for gas exchange (stomata) on needles (generally requires a hand lens for identification). ![]() Trees compared to smaller trees in young-growth stands. Symptoms generally appear in older groups of adjacent needles. Lophodermium: Fruiting structures are black and elliptical, often with black zone lines crossing needles. Smaller trees are often more severely affected than large trees. Thinning and pruning trees to increaseĪir movement in the crown can reduce infection. Although usually not necessary, chemical control is effective when applied around bud break. One-year-old needles, and tan two-year-old needles, often interspersed with healthy foliage. This results in a distinctive pattern of green new growth, red-brown Red-brown foliage discoloration symptoms become apparent one year after infection, with needles turning tan-brown after two years. Spores are released from mature fruiting structures on infected two-year-old needles in spring to infect newly emerging foliageĭuring shoot elongation. ![]() Lirula: Fruiting structures are black and elongated on the undersides of needles. Rhizosphaera and Lirula needle casts are considered more damaging than Lophodermium needle cast in Alaska. Where persistent needle wetness promotes foliage disease. Symptoms are often most severe in the lower and interior tree crown, These diseases can be distinguished based on the fungal fruiting structures on needles, and (when severe) also on the pattern of foliage discoloration.
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