Sphaeropsis sapinea (Sphaeropsis blight)
Identity
- Preferred Scientific Name
- Sphaeropsis sapinea (Fr.) Dyko & B. Sutton 1980
- Preferred Common Name
- Sphaeropsis blight
- Other Scientific Names
- Botryodiplodia pinea (Desm.) Petr. 1922
- Diplodia conigena Desm. 1846
- Diplodia pinastri Grove 1916
- Diplodia pinea (Desm.) J. Kickx F. 1867
- Granulodiplodia sapinea (Fr.) M. Morelet & Lanier 1973
- Macrophoma pinea (Desm.) Petr. & Syd. 1926
- Macrophoma sapinea (Fr.) Petr. 1962
- Phoma pinastri Lév.
- Sphaeria pinea Desm. 1842
- Sphaeropsis ellisii Sacc. 1884
- Sphaeropsis pinastri (Lév.) Sacc. 1884
- International Common Names
- Englishdieback: pineDiplodia blightDiplodia cankerDiplodia shoot blightDiplodia tip blightshoot blight: conifersshoot dieback: conifersSphaeropsis cankerSphaeropsis shoot blightSphaeropsis tip blighttip blight: coniferstwig blight: coniferswhorl canker: pine
- Spanishmarchitez de los brotes del pino
- Frenchdeperissement des pousses du pin
- Local Common Names
- GermanyTriebspitzenkrankheit: Kiefer
- EPPO code
- DIPDPI (Diplodia pinea)
Pictures
Distribution
Host Plants and Other Plants Affected
Symptoms
A variety of symptoms are exhibited by cones, seed and young seedlings in response to colonization by S. sapinea. Female cones may be killed before full development, becoming dark, shrunken and deformed. Symptoms resulting from in vitro inoculation range from reduced germination to death of seed of several Central American pine species (Rees and Webber, 1988). Radicles of germinants were shortened, thickened and discoloured, and if killed became flaccid and brown. Similarly, Fisher (1941) noted reduced germination and radicle decay for Pinus resinosa and P. ponderosa.Palmer and Nicholls (1985) noted shoot blight of 1-year-old red pine seedlings evidenced by dead terminal buds and upper needles and symptoms on older seedlings including death of new shoots during shoot expansion and needle elongation. Exudation of resin droplets may be the first symptom of infection on either needles or succulent stems. Needles become discoloured and are often killed without elongating beyond fascicle sheaths. Water-soaked, purplish-brown stem lesions may expand as stems become stunted, curled, hardened, resin-encrusted and necrotic (Chou, 1976). Seedlings in nurseries and recently planted seedlings and saplings may be killed by Sphaeropsis collar rot (Palmer and Nicholls, 1985; Stanosz and Cummings Carlson, 1996), characterized by discoloured, necrotic bark and dark discoloration of wood in the lower stem and root collar. Foliage on the entire seedling or sapling becomes chlorotic, desiccated and brown as the stem is girdled.Initial symptoms of shoot blight on established trees resemble those on seedlings, but symptoms become more severe as colonization progresses. The fungus proceeds from killed shoot tips or diseased cones into woody stems to cause cankers (Waterman, 1943; Chou, 1976). Exudation of resin may be copious and dead needles are often retained. On younger stems, smooth bark may be depressed and turn brown as it dies. The underlying wood may be stained green to brown to blue to black and be resin-soaked. Older cankers may be bounded by callus. Entire branches or whorls of branches may be killed as the pathogen progressively invades, and substantial dieback or dead tops can result. Subsequent forking or branching of diseased leaders may result in substantial defect (Currie and Toes, 1978).Severe crown symptoms and tree death may follow hailstorms, drought or pruning. Zwolinski et al. (1990b) estimated loss of as much as half the live foliage, death of 50-80% of leaders, and up to almost 20% tree mortality in Pinus radiata plantations in South Africa in the months after a hail event. Chou (1987) described crown wilt of P. radiata associated with the colonization and killing of inner bark, the extensive invasion and blue staining of wood, and subsequent desiccation. Grey to blue to black staining of wood may occur in freshly cut logs and green lumber (Young, 1937; Kreber et al., 2001) and also in roots colonized by S. sapinea (Wingfield and Knox-Davies, 1980).
List of Symptoms/Signs
Symptom or sign | Life stages | Sign or diagnosis |
---|---|---|
Plants/Fruit/abnormal shape | ||
Plants/Fruit/discoloration | ||
Plants/Fruit/lesions: black or brown | ||
Plants/Fruit/ooze | ||
Plants/Fruit/reduced size | ||
Plants/Growing point/dieback | ||
Plants/Growing point/discoloration | ||
Plants/Growing point/distortion | ||
Plants/Growing point/lesions | ||
Plants/Growing point/wilt | ||
Plants/Leaves/necrotic areas | ||
Plants/Leaves/ooze | ||
Plants/Leaves/wilting | ||
Plants/Leaves/yellowed or dead | ||
Plants/Roots/soft rot of cortex | ||
Plants/Seeds/discolorations | ||
Plants/Seeds/distortion | ||
Plants/Seeds/rot | ||
Plants/Seeds/shrivelled | ||
Plants/Stems/canker on woody stem | ||
Plants/Stems/dieback | ||
Plants/Stems/discoloration | ||
Plants/Stems/discoloration of bark | ||
Plants/Stems/gummosis or resinosis | ||
Plants/Stems/internal discoloration | ||
Plants/Stems/necrosis | ||
Plants/Stems/ooze | ||
Plants/Whole plant/discoloration | ||
Plants/Whole plant/plant dead; dieback | ||
Plants/Whole plant/seedling blight |
Prevention and Control
Phytosanitary Measures
Specific information is lacking regarding the effectiveness of measures to disinfest seed, or treat logs or lumber, to prevent movement of S. sapinea.
Cultural Control and Sanitary Methods
The removal and destruction of colonized shoots, branches and cones can prevent further invasion of a diseased tree and reduce the availability of inoculum for further spread. Host species should not be used for windbreaks in nurseries and it may be desirable to remove significantly damaged trees from production areas. Excessive pruning should be avoided and pruning and shearing should be limited to dry weather when inoculum is less available. The association of disease with water stress (Nicholls and Ostry, 1990; Blodgett et al., 1997a, b) and altered nutrition (De Kam et al., 1991; Van Dijk et al., 1992; Stanosz and Trobaugh, 1996) suggests that maintaining favourable moisture status and avoiding excesses in nitrogen may reduce the incidence and/or severity of disease. Less susceptible or non-host species should be considered for sites with a history of unacceptable damage.
Host-Plant Resistance
The incidence and severity of symptoms varies among host species. The most damaged species are found among the two- and three-needled 'hard pines' (subgenus Diploxylon); five-needled 'soft pines' (subgenus Haploxylon) and non-pine hosts are generally less susceptible. Within the former group, non-wounded Pinus resinosa seedlings inoculated with conidia in greenhouse trials exhibited a lower incidence and less severe symptoms than Pinus banksiana seedlings (Blodgett and Stanosz, 1997). Ranked from greatest to least severity of symptoms in response to wounding and inoculation of terminal shoots with S. sapinea were Pinus sylvestris, P. resinosa, Picea pungens, Pinus mugo, Pseudotsuga menziesii and Abies balsamea (Blodgett and Stanosz, 1999). Differences in responses of pine species cultivated in South Africa to inoculation with S. sapinea were quantified by Swart et al. (1988). In a growth chamber experiment, inoculated seedlings of Pinus kesiya, P. pinaster and P. radiata exhibited greater frequencies of dead shoots than those of P. elliottii, P. patula and P. taeda. On trees inoculated in the field, a greater frequency of shoot death and longer cambial lesions occurred for P. radiata than for P. elliottii and P. pinaster.Variation in host response to S. sapinea has also been observed within species. Burdon et al. (1982) studied responses of inoculated progenies of parents selected for freedom from S. sapinea-associated shoot dieback on a site of very high disease incidence. As a group these progenies showed a lower incidence of disease than control seedlots, and there was also considerable variation among these progenies. Gerhold et al. (1994) noted differences in response to inoculation among varieties of P. sylvestris seedlings. Variation in disease tolerance between provenances and among families of Pinus greggii following natural infection by S. sapinea has also been reported (Smith et al., 2002).
Chemical Control
Fungicide applications have reduced the incidence of shoot blight and may be appropriate for nurseries, Christmas tree plantations, ornamental plantings and windbreaks (Van Der Westhuizen, 1968; Schweitzer and Sinclair, 1976; Peterson, 1977; Palmer et al., 1986; Stanosz and Smith, 1996). Stanosz and Smith (1996) found similar efficacy of thiophanate methyl and chlorothalonil on Pinus resinosa seedlings. However, asymptomatic persistence of virulent strains of S. sapinea can occur on or in hosts in spite of fungicide use (Stanosz et al., 1997). Proliferation of S. sapinea in raw logs and freshly sawn lumber has been suppressed by treatment with methyl bisthiocyanate and 2-n-octyl-4-isothiazolin-3-one (Kreber et al., 2001).
Impact
Whether or not losses have been expressed in economic terms, significant damage has been caused by S. sapinea in a variety of situations. Palmer and Nicholls (1985) reported loss of 35% of 1-year-old red pine seedlings in a Wisconsin nursery (loss of more than 1 million seedlings). In the same state, mortality of newly planted or established red pine saplings during a drought year was as great as 95% in some plantations. Lower stems and root collars frequently yielded S. sapinea, which proliferates to rapidly girdle and kill many trees under these conditions (Stanosz and Cummings Carlson, 1996; Stanosz et al., 2001). Nicholls and Ostry (1990) reported tree mortality in Pinus banksiana and P. resinosa plantations ranging from 2 to 51% in Minnesota and Wisconsin, and indicated that S. sapinea was consistently associated with dead trees. Trees in windbreaks also have been severely damaged in central USA (Peterson and Wysong, 1968).Losses in the production of Pinus radiata in the southern hemisphere have been reported in more detail. Zwolinski et al. (1990a) quantified the losses resulting from a post-hail outbreak of dieback induced by S. sapinea affecting approximately 2000 ha of mostly P. radiata in the Cape Province of South Africa. The timber loss in compartments prematurely harvested was about 28% of the volume and 55% of the value of potential production. The percentage volume loss increased with plantation age, with the greatest losses recorded on good quality sites. Great losses were also documented for a P. radiata stand affected by S. sapinea in New Zealand (Currie and Toes, 1978). There was a close association between the severity of dieback, tree malformation, and loss in merchantable tree volume. A reduction of 63% in merchantable tree volume was estimated. In contrast, despite a high incidence of top death in some (usually younger) stands of P. radiata in north-eastern Victoria, Australia, the overall effect on tree growth and on volume and value of merchantable wood was small (Wright and Marks, 1970). The volume of degraded wood in this study ranged from 0.5 to 5.5% of the possible volume.
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Published online: 16 November 2021
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