Management strategies rely heavily on good cultural practices as well as fungicides. The fungus overwinters in infected needles. Symptoms usually appear about 3 weeks after infection. The most favorable conditions for infection occur when temperatures are around 68☏ and humidity is high. The fungus produces spores from spring through fall.

The Cercospora needle blight fungus (Passalora sequoia) produces olive-green tufts of spores on a black base embedded in the surface of infected leaves. A magnifying lens is helpful for observing this feature. The fruiting structures may appear fuzzy and dark olive-brown if they are producing lots of spores (Figure 1). Tiny, black fruiting structures may be visible on brown or gray needles. As infected needles age, they may turn from brown to gray. Symptoms of Cercospora needle blight usually begin in the lower part of the tree canopy and move from the interior of the plant toward the branch tips. Cercospora needle blight ( Passalora sequioiae) The presence of small black fruiting structures can help differentiate needle blight diseases from similar damage caused by other factors. Air circulation often is poor in hedge and Christmas tree plantings, providing a high humidity environment that is ideal for fungal infection. Leaf wetness and high humidity favor infection of the leaves. In Mississippi, three fungi are responsible for most Leyland needle blight diseases. Needle blights are characterized by rapid browning of needles, which often leads to dieback of twigs and branches. Pot-bound Leylands are more susceptible to winter foliage burn and diseases and will eventually die. Before planting, carefully examine the root systems of potted Leylands to ensure they are not pot-bound. Trees on sites with poor drainage often have severe twig dieback problems, whether they are open-grown or in hedges, and root disease also can be a problem.ĭeformed roots are another common cause of tree failure in Mississippi. Leylands require well-drained soil and do not tolerate low-lying sites, heavy clay soils, or poor drainage. This publication covers the most common diseases and disorders impacting Leylands in Mississippi. Unfortunately, many of these uses involve close plant spacing, which, when coupled with the climate and site conditions common to Mississippi, can reduce the vigor of Leylands and make them more susceptible to certain problems. Leyland cypress (× Hesperotropsis leylandii) is a feathery-leaved evergreen with a reputation for rapid growth and hardiness that has made it a popular choice for Christmas trees, privacy hedges, and windbreaks.

Bronze spot needle blight