What causes Dothistroma?

Dothistroma needle blight is caused by the fungus Mycosphaerella pini Rostr. This common pine pathogen kills needles of all ages and can weaken or kill Austrian pine trees.

What does needle blight look like?

What does Dothistroma needle blight look like? Dothistroma needle blight first appears as dark green, water-soaked spots on the needles. The spots become tan, yellow, or reddish-brown, and may encircle the needles to form bands.

What causes blight on pine trees?

Causes: Brown spot needle blight is caused by the fungus Mycosphaerella dearnessii. Infections spread in wet weather when spores attack several times throughout the season. The splashing of rainwater enables the spores to spread rapidly and infect large areas of the tree.

When do you spray for Diplodia tip blight?

To manage Diplodia tip blight requires three fungicide applications, once when buds begin to swell (late April), again in early May, and again in mid-May. Dothistroma needle blight can be managed by spraying once in mid-May and again four to six weeks later.

What does Dothistroma needle blight look like in Wisconsin?

Dothistroma needle blight is a common needle disease that can affect over thirty species of pine trees. In Wisconsin, Austrian pines are most commonly and severely affected by this disease. What does Dothistroma needle blight look like?

What can I do to prevent Dothistroma needle blight?

Use the mature size of the tree as a spacing guide when planting. Remove the bottom most branches from the trunk to help increase circulation around the tree canopy. Remove all weeds under the trees. Maintain a 3 to 4 inch deep, even layer of wood chip mulch around your tree to prevent weed growth.

How long does it take for a Dothistroma needle to die?

The spots become tan, yellow, or reddish-brown, and may encircle the needles to form bands. The tip of the needle beyond the band eventually dies leaving the base of the needle alive and green. Young trees are more likely to suffer damage than older trees. Seedlings (<1 yr. old) can be killed within a year after infection.

When to use copper fungicide on Dothistroma needles?

If trees have a history of Dothistroma needle blight, copper fungicides can be used to protect new needles from infection. once just before buds open in the spring (typically in mid-May) to protect previous year’s needles. once after new needles have grown to their full length (in early to mid summer).