Lophodermium needle cast on 2-0 nursery stock and 5 year old scotch pine, Spanish variety.
BROWN SPOT NEEDLE BLIGHT
Brown spot or brown spot needle blight is caused by the fungus Scirrhia acicola. Brown spot occurs in all the coastal states from Virginia to Texas, and inland to Arkansas and Tennessee. All southern pines are attacked by the fungus, but only longleaf pine seedlings are seriously damaged.
Brown spot needle blight on longleaf pine reproduction.
Initial infection of pine needles results in the development of small, circular spots of grey green color, which later turn brown. As the fungus continues to grow, a necrotic area encircles the needle, appearing as a brown band. The infected area will then increase in size, eventually resulting in the death of the needle. Fruiting bodies, called acervuli, develop in the dead areas of the needle. Spores are extruded from the acervuli in a water soluble gelatinuous matrix throughout the entire year. The spores are washed apart and splashed short distances by rain drops. These spores spread the disease from seedling to seedling. During the winter and early spring, the sexual stage of the fungus is produced on dead needles. Ascospores, produced in a fruiting body called a perithecium, are light and wind-disseminated. These spores are responsible for disease spread. During the grass stage, seedlings often become heavily infected by the brown spot fungus, resulting in partial to complete defoliation. Seedlings which are nearly defoliated every year remain in the grass stage and eventually die. Three successive years of complete defoliation will result in death. The disease is very damaging during wet years, especially in areas where the fungus has become well established in the absence of controls.
The disease can be reduced by control burning during the winter months. On seedlings, fire burns the diseased needles and reduces the amount of available inoculum for reinfection, leaving the large terminal bud unharmed. Often a single prescribed burn reduces the disease intensity to such low levels that vigorous seedling height growth begins the following year. Fungicide sprays will also reduce brown spot on high valued trees.