However, over-fertilization can make trees more susceptible. The holding of dead needles and the resin flow from shoots and branches are typical of tip blight. It kills branches by causing cankers and infects the vascular tissue with blue stain. These black dots will be on the needles, usually under the sheath, as well as on the stems and on the cones’ scales. Diplodia tip blight causes the most damage to mature trees that are stressed. Studies have also shown that Cambistat can reduce the latent stage of diplodia tip blight. Seasons: Diplodia tip blight is present year-round. If you have had problems before with Diplodia you should consider applying fungicides beginning as the candles are expanding and then two more applications at 10-day intervals. Diplodia kills young needles and actively growing shoots of Austrian, red and other 2 to 3 needle pines. Reference to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned. For Dothistroma needle blight, spray about mid-May (coincides with the final Diplodia spray) and again about July 1; the first spray protects the previous year's needles and the second spray protects the current year's needles as well. Make sure to read and follow label directions. Prune off infected branches during dry periods in early spring or fall. The black fruiting bodies are relatively large and can be seen easily with a hand lens and even the naked eye. Untreated, repeat infections can spread from needle fascicles to the entire tree branch, and ultimately result in tree death. Michigan State University Extension programs and materials are open to all without regard to race, color, national origin, gender, gender identity, religion, age, height, weight, disability, political beliefs, sexual orientation, marital status, family status or veteran status. Good hygiene is an easy way to minimize and prevent the disease. Also, when practical prune and remove infected twigs and branches during dry weather. When symptoms of the diseases have disappeared, … Remove and burn or bury the contaminated materials to prevent further spreads. Issued in furtherance of MSU Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Diplodia kills young needles and actively growing shoots of Austrian, red and other 2 to 3 needle pines. Symptoms occur on lower branches first and work their way up the tree. The product you choose will depend on the site of the application such as Christmas trees, nurseries or landscapes. MSU is an affirmative-action, equal-opportunity employer, committed to achieving excellence through a diverse workforce and inclusive culture that encourages all people to reach their full potential. If, later in the summer, more than 10 percent of the trees have severe shoot blight, consider a spray program again next spring. For more information, visit https://extension.msu.edu. Proper irrigation and mulching, as well as fertilization to address nutrient deficiencies, all help to maintain tree vigor. If, later in the summer, more than 10 percent of the trees have severe shoot blight, consider a spray program again next spring. During wet conditions, spores travel to and penetrate newly emerging needles and quickly cause necrosis. The fruiting bodies appear in summer. Time fungicide applications to protect new growth from bud break through full candle elongation. Any infected plant material needs to be removed so the spores cannot jump to previously healthy tissue.