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Dothistroma Needle Blight: A Disease of Pine Trees
Dothistroma needle blight is a fungal disease that affects many species of pine. It is caused by the fungus Dothistroma septosporum. While it is most common in cooler, wetter regions, the disease has been found across the United States. Although there is no direct confirmation that it is present in Houston specifically, the warm, humid conditions of the area could support the development of the disease under the right circumstances.
Pines That Are Affected
Dothistroma needle blight has been confirmed on more than 30 species of pine. It is especially problematic on Austrian pine (Pinus nigra) and ponderosa pine (Pinus ponderosa), which are highly susceptible. Pinus taeda, commonly known as loblolly pine and widespread in Texas, has also been reported with symptoms of this disease in some areas. Dothistroma needle blight has been observed in Texas.
Recognizing the Symptoms
This disease typically affects older needles first. Small yellow to tan spots appear on the needles, eventually turning into reddish-brown bands. Often, the tips of the needles will die and turn brown while the base remains green. Over time, needles may drop from the tree. These symptoms typically become visible in mid to late summer.
The banded needle appearance is one of the most distinguishing features of Dothistroma needle blight. Infected trees may begin to look thin, especially in the lower canopy, as more needles are lost over time.
How the Disease Spreads
Dothistroma needle blight spreads primarily through rain or irrigation that splashes fungal spores from infected needles to nearby healthy ones. Wind and overhead watering can also contribute. The fungus overwinters in infected needles and releases new spores during wet conditions, typically in the spring and early summer.
Although there is no direct confirmation of cases in Houston, the city’s warm and humid climate, along with frequent rain, might support the disease’s spread if susceptible pine species are present and conditions are favorable.
Why It Matters
Dothistroma needle blight can cause gradual weakening of pine trees by reducing their photosynthetic capacity. Although it does not usually kill trees quickly, repeated infections may lead to branch dieback and reduced growth over time. This can lower the aesthetic and functional value of landscape trees.
In areas where loblolly pines are used in landscaping or natural stands, such as in parts of Texas, awareness of this disease is important, especially when trees show signs of needle loss or discoloration.
What to Look For
If you are observing pine trees in your area, these are common signs of Dothistroma needle blight:
Yellow or tan spots on older needles
Reddish-brown bands across the needles
Browning and dropping of needle tips
Thinning of foliage, especially lower branches
These symptoms can vary depending on species and environmental conditions, so they should be evaluated carefully.
In Summary
Dothistroma needle blight is a fungal disease affecting many pine species. It is confirmed to occur in Texas and can infect loblolly pine, a species common to the region. While there is no direct evidence of the disease in Houston, the local climate could support its development. Knowing the signs of this disease can help tree care professionals and property owners stay informed about potential threats to pine trees in their landscapes.
For anyone concerned about pine health, ArborTrue continues to share science-based updates about tree diseases that may affect the region.
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ArborTrue is a science-based tree service company in the greater Houston area. We also serve Austin and other parts of Central Texas. We provide a range of services including tree trimming, tree pruning, tree removal, tree planting, arborist consultations, and more. Call us today at 832-980-8733 (Houston) or at 512-546-3833 (Austin) or reach out to us online to schedule an appointment.
