Diplodia pinea (Botryosphaeriaceae) is one of the most important pathogens of pines in South Africa. The fungus has been associated with a number of different disease symptoms, including shoot blight of seedlings and trees (die-back), stem cankers, root diseases and blue stain of timber (Wingfield and Knox-Davies 1980; Swart et al., 1987; Slippers and Wingfield 2007).
Diplodia pinea die-back following hail damage has been known in South Africa since the early 1900's. This serious disease, which accounts for the notoriety of the pathogen worldwide, has led to the restriction of the most susceptible species (Pinus patula, P. pinaster and P. radiata) to areas where hail is infrequent. Pinus patula is still planted in summer rainfall areas and severe losses commonly occur. Although less frequent, hailstorms do occur in areas where P. radiata is planted and these often also lead to substantial losses.
Diplodia pinea exists as a saprophyte on dead bark, cones and needles and is best known as an opportunist that infects wounds on susceptible pines. The fungus can, however, behave as a primary pathogen and infect young, unwounded pine shoots. Moisture is necessary for infection by D. pinea and young shoots become infected when rains coincide with warm temperatures, at the onset of growth. Once established in the shoots, D. pinea moves down the pith, where it can remain dormant. When pines are stressed, the fungus moves out of the pith and causes stem cankers.
A serious root disease of P. elliottii and P. taeda caused by D. pinea has been found in many parts of South Africa. Characteristic symptoms of this disease are dark-blue, radial lesions in young roots which extend to larger roots and into the trunk of diseased trees (Wingfield and Knox-Davies 1980). Needles become chlorotic and are shed. Pinus taeda is apparently most susceptible and the disease is always associated with stress due to factors such as overstocking, drought and plantings on poor sites.
Diplodia pinea (Botryosphaeriaceae) is one of the most important pathogens of pines in South Africa. The fungus has been associated with a number of different disease symptoms, including shoot blight of seedlings and trees (die-back), stem cankers, root diseases and blue stain of timber (Wingfield and Knox-Davies 1980; Swart et al., 1987; Slippers and Wingfield 2007).
Diplodia pinea die-back following hail damage has been known in South Africa since the early 1900's. This serious disease, which accounts for the notoriety of the pathogen worldwide, has led to the restriction of the most susceptible species (Pinus patula, P. pinaster and P. radiata) to areas where hail is infrequent. Pinus patula is still planted in summer rainfall areas and severe losses commonly occur. Although less frequent, hailstorms do occur in areas where P. radiata is planted and these often also lead to substantial losses.
Diplodia pinea exists as a saprophyte on dead bark, cones and needles and is best known as an opportunist that infects wounds on susceptible pines. The fungus can, however, behave as a primary pathogen and infect young, unwounded pine shoots. Moisture is necessary for infection by D. pinea and young shoots become infected when rains coincide with warm temperatures, at the onset of growth. Once established in the shoots, D. pinea moves down the pith, where it can remain dormant. When pines are stressed, the fungus moves out of the pith and causes stem cankers.
A serious root disease of P. elliottii and P. taeda caused by D. pinea has been found in many parts of South Africa. Characteristic symptoms of this disease are dark-blue, radial lesions in young roots which extend to larger roots and into the trunk of diseased trees (Wingfield and Knox-Davies 1980). Needles become chlorotic and are shed. Pinus taeda is apparently most susceptible and the disease is always associated with stress due to factors such as overstocking, drought and plantings on poor sites.
Disease name: |
Diplodia diseases |
|
Causal agents: |
Diplodia pinea (Sphaeropsis sapinea) | |
| Trees affected: | Pinus spp., especially P. patula, P. radiata |
|
Tree part |
Stems, branches, roots, sawn timber | |
| Impact: | Tip and branch die-back, stem cankers, blue stain |
|
Symptoms: |
Sunken cankers on stems/branches, blue stain of affected parts, resin oozing from lesions, branch/tip death |
