What is Sphaeropsis Shoot Blight?
Sphaeropsis Shoot Blight, formerly known as Diplodia, is a serious disease of many pine species and other conifers. Sphaeropsis kills many on the growing points on branches, which eventually leads to the death of the branches. Austrian Pine is a commonly affected ornamental.
What are the symptoms and effects of Sphaeropsis Shoot Blight?
Resin droplets are often the first indication of Sphaeropsis Shoot Blight. They exude from small, discolored lesions on needles and shoots. The lesions grow in size, and needles turn yellow, then reddish-brown as they die. Needles on affected shoots may not grow to full length and may die prematurely. They may also stick together due to abundant resin flow.
How do you control Sphaeropsis Shoot Blight?
Cultural treatment: Stressed trees are particularly susceptible to Sphaeropsis. Thus, measures to improve tree vigor help them resist shoot blight. Irrigation during periods of drought encourage healthy root development, provide adequate rooting zones; avoid soil compaction, and correct poor drainage. Fertilization will encourage root growth.
Chemical treatment: Application of a fungicide that contains thiophanate methyl may be effective if the inoculum concentration is not too great. In Wisconsin this period usually begins in May-early May in the south, later in the north. An application should be made at bud break and at least one more time about 14 days later.