Diplodia Tip Blight

Pine tip blight (Sphaeropsis sapinea) is a serious disease of exotic pines such as Austrian pine (Pinus nigra) and Scots pine (Pinus sylvestris) growing in landscapes. Tip blight (Diplodia sapinea) has been documented on 20 pine species throughout the Central and Eastern United States, as well as California and Hawaii. Stress from drought, compaction, mechanical damage and other abiotic factors make this disease worse and the disease is most often found on mature stressed pine trees.

This disease kills current year’s shoots, which means that infections year after year can weaken and eventually kill large trees. Recent studies have indicated that the pathogen can live in a latent state in healthy pine shoots throughout infected and healthy trees. Shifts from latent state to pathogenic state may correlate to abiotic stress factors.

Treatment Strategy

Diplodia tip blight causes the most damage to trees that are old or weak. Keeping trees in good vigor with deep watering during droughts, nutrition with fertilization or compost and wood mulch, and control of insects can help decrease susceptibility to the disease. However, over-fertilization can make trees more susceptible. Fungicides can assist with control of tip blight, but it is very important to protect the new growth in the spring. Applications should start just prior to bud break and continue every 14 days until full candle extension.

Cambistat has fungistatic properties that have a direct mode of action on fungal diseases and Cambistat improves the health of trees which improves their ability to withstand stress induced diseases. For best results, Cambistat should be applied as part of an overall management strategy for tip blight including traditional fungicide spray applications and cultural practices aimed at improving tree health.

Other Treatment Practices

  • Avoid planting susceptible pine species.
  • Prune off infected branches during dry periods in early spring or fall. Disinfect pruning tools between cuts with 70% rubbing alcohol.
  • Rake up and remove fallen needles, twigs, and cones.
  • Promote health and vigor with proper irrigation, mulching, proper pruning, root collar excavation and prescription based fertilization practices.
    • Adequate water is a key factor in maintaining stress free plants. A slow, deep watering event once every few weeks during dry conditions will help maintain soil moisture levels and minimize stress.
    • Mulch is very beneficial for all trees because it reduces competition with turf and moderates soil temperature and moisture levels. The addition of 3 inches of wood chips or shredded bark under the drip line can have a very beneficial effect by holding in moisture and promoting healthy fibrous roots.
    • Cambistat can be also be used to promote tree health and reduce the incidence and severity of stress mediated diseases and insect problems on trees growing in urban areas

Foliar Spray Using Talaris 4.5F

Foliar Spray Using Junction WSP

Foliar Spray Using CuPro 5000

Expected Results

There are numerous reasons for Cambistat’s ability to reduce the incidence and severity of these diseases. Cambistat has fungistatic properties that have a direct mode of action on fungal diseases and Cambistat improves the health of trees which improves their ability to withstand stress induced diseases. For best results, Cambistat should be applied as part of an overall management strategy for tip blight including traditional fungicide spray applications and cultural practices aimed at improving tree health.

Foliar spray fungicide applications later in the growing season do not work. If using CuPro or Junction, the 2nd and 3rd applications will also overlap and provide protection vs. dothistroma. It is important to thorough coverage is achieved with the spray treatments.

Signs of Damage

  • Brown needles at the tip of the current year’s growth are the first symptoms
  • Symptoms occur on lower branches first and work their way up the tree
  • Shoots do not develop to full maturity and needles turn brown in mid to late summer
  • Resin oozes from cankers at the base of new shoots in spring
  • Small, black fruiting bodies (pycnidia) may be seen at the base of the diseased needle, when using a hand lens

Photo: Wikimedia Commons

Photo: Rainbow Ecoscience

Trees At Risk

  • Over 20 pine species are infected by Diplodia, but it is most severe on 2 and 3 needled pines
  • Austrian (Pinus nigra)
  • Scots Pine (Pinus sylvestris)
  • Ponderosa Pine (Pinus ponderosa)
  • Mugo Pine (Pinus mugo)

Biology

  • The fungus overwinters in infected cones, shoots, and needles.
  • During wet conditions, spores travel to and penetrate newly emerging needles and quickly cause necrosis.
  • Second-year seed cones are infected in late May or early June and serve as a reservoir of future inoculum.

A Treatment Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments by forestryimages.org

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