Diplodia Shoot (Tip) Blight

A common pine disease.

Diplodia shoot blight (or tip blight), Diplodia sapinea, (formerly known as Sphaeropsis tip blight) is a fungal disease that kills the tips of the branches of pines, and less frequently spruce and firs. In the blight stage, it can cause severe dieback and the fungus can grow into the stems and main trunk where it becomes a canker disease. It is considered a secondary infection in that weakened trees are more readily infected; Healthy trees are more resistant to infection.

Download Diplodia Shoot (Tip) Blight Fact Sheet

Treatment Strategy

Because Diplodia is a disease of a weakened tree, the treatment is a two step process.

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Diplodia Shoot (Tip) Blight Treatment Option 1

The first step is to increase the health of the tree

• Properly water during prolonged drought periods or on dry sites being sure not to get the leaves wet.

• Avoid or relieve soil compaction or grade changes to the soil.

• Place rings of mulch 3″ deep around the trees to promote healthy root growth.

• Remove dead or dying branches from infected trees when possible to remove disease sources.

• Apply a multi nutrient fertilizer that has little or NO nitrogen. Nitrogen will increase the fungal growth. Do not use lawn fertilizers to fertilize your tree.

• Do not use weed killers or herbicides near the trees as these can injure and weaken the tree.

• The use of a growth hormone regulator called Cambistat has been shown to stimulate root growth, increase defense chemicals, and increase drought tolerance which may help affected trees overcome Diplodia.

Application Type-Soil drench

DIY Product/Equipment Needed:

• Cambistat

Soil Drench Kit

• Graduated cylinder measuring in mL

• Bucket or Watering can

• Shovel

Diplodia Shoot (Tip) Blight Treatment Option 2

The second step is to help the tree with its defense system

Fungicide protection with a product called Cu Pro is required from bud swell through full growth. Three sprays are needed, spaced 10 to 14 days apart, starting just before bud break. During rainy springs, a fourth application, 10 days after the third, will be necessary. Be sure to cover the lowest branches completely because new infections usually occur lower on the tree.

Application Type - Foliar Spray

DIY Product/Equipment Needed:

• Cu Pro

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Diplodia Shoot (Tip) Blight DIY Kit

Option 1

Application Type - Soil drench

DIY Product/Equipment Needed:

• Cambistat

• Soil Drench Kit

• Graduated cylinder measuring in mL

• Bucket or Watering can

• Shovel

Option 2

Application Type - Foliar Spray

DIY Product/Equipment Needed:

• Cu Pro ™

• Hand pump sprayer with wand

• Gloves

• Safety glasses


How Is It Spread?

During moist weather in spring, spores ooze from last year’s fungus that is growing on dead tissue. Wind and rain carry the spores to young needles and buds, infecting current season needles and developing shoots from late April to mid-June. Within a year, the fungus produces more spores. Wet conditions during this period are needed for the disease to continue its infection progression.

Susceptible Trees

Diplodia tip blight most frequently affects Austrian pines but can also damage Scots pine, ponderosa pine, and mugo pine. Spruce and fir can also be affected. The disease occurs most often in well established plantings; trees 25 to 30 years old can be especially vulnerable.

Symptoms

The most common symptoms of Diplodia tip or shoot blight are stunting and browning of current-year shoots in the lower branches. Dieback of the current season’s growth year-after-year, eventually results in dead limbs and stunted tree growth. The disease is initially confined to the lower branches, with time however, it progresses upward until only the very upper branches are green, while the middle and lower portion of the tree are brown with brittle, dead branches. Stunted, straw-colored-to gray needles are most likely to host fungal spores, but cones can also be infected. Small black dots – the spores – are visible at the base of needles and on cones.

Lookalikes

None

Related/Similar Problems

Drought, construction damage

Timing

Spring

Urgency

Moderate

Risk of Spreading

High

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