Seasonal Patterns of Ascospore Discharge by<i>Leptosphaeria maculans</i>in Relation to Blackleg of Oilseed Rape

McGee, D. C.; Petrie, Graham

doi:10.1094/phyto-69-586

Cited by 50 publications

(20 citation statements)

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“… a Australia, Bokor et al . (1975), McGee (1974, 1977) (Barbetti M.J., unpublished); Canada, McGee & Petrie (1979), Kharbanda (1993), Rempel & Hall (1993); Europe, Pérès et al . (1997), Thürwächter et al .…”

Section: Epidemiology Of L Maculans In Different Continentsmentioning

confidence: 99%

“…In Ontario, Canada, ascospores may be released from debris of recently harvested crops from September to November, when they can infect seedlings of new winter oilseed rape crops (Rempel & Hall, 1993). In western Canada, by contrast, ascospores are released from debris from May to August after the long, cold winter, when they can infect leaves of the new spring oilseed rape crops (McGee & Petrie, 1979; Kharbanda, 1993). In western Europe, ascospores are released from debris of the previous season's winter oilseed rape crop from late September onwards throughout the autumn/winter period, although the timing of maxima in ascospore release differs from season to season (Gladders & Musa, 1980; Pérès et al ., 1997; Thürwächter et al ., 1999).…”

Section: Epidemiology Of L Maculans In Different Continentsmentioning

confidence: 99%

“…(1995), Harrison et al . (1995), P. D. Kharbanda (unpublished); Manitoba, Platford (1996); Saskatchewan, McGee & Petrie (1979), Petrie (1995b); Kaminski et al . (1996).…”

Section: Factors Affecting Severity Of L Maculans Epidemicsmentioning

confidence: 99%

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Epidemiology and management of Leptosphaeria maculans (phoma stem canker) on oilseed rape in Australia, Canada and Europe

Kharbanda²,

et al. 2001

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Phoma stem canker (blackleg), caused by Leptosphaeria maculans, is an important disease on oilseed rape (canola, rapeseed, Brassica napus, Brassica juncea, Brassica rapa) causing seedling death, lodging or early senescence in Australia, Canada and Europe, but not in China. The two forms of L. maculans (A group and B group) that occur on oilseed rape are now considered to be separate species. The epidemiology and severity of phoma stem canker differs between continents due to differences in the pathogen population structure, oilseed rape species and cultivars grown, climate and agricultural practices. Epidemics are most severe in Australia, where only the A group occurs, and can be damaging in Canada and western Europe, where both A and B groups occur, although their proportions vary within regions and throughout the year. Epidemics are slight in China, where the A group has not been found. Dry climates (Australia, western Canada) lengthen the persistence of infected debris and may synchronize the release of airborne ascospores (after rain) with seedling emergence. L. maculans spreads from cotyledon and leaf infections down petioles to reach the stem, with infections on cotyledons and leaves early in the season producing the most damaging stem cankers at the stem base (crown). Development of both crown cankers and phoma stem lesions higher up stems is most rapid in regions with high temperatures from flowering to harvest, such as Australia and Canada. Breeding for resistance (genetic, disease escape or tolerance), stubble management, crop rotation and fungicide seed treatments are important strategies for control of phoma stem canker in all areas. Fungicide spray treatments are justified only in regions such as western Europe where high yields are obtained, and accurate forecasts of epidemic severity are needed to optimize their use.

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Section: Epidemiology Of L Maculans In Different Continentsmentioning

confidence: 99%

Section: Epidemiology Of L Maculans In Different Continentsmentioning

confidence: 99%

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Epidemiology and management of Leptosphaeria maculans (phoma stem canker) on oilseed rape in Australia, Canada and Europe

Kharbanda²,

et al. 2001

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“…In Australia, harvest is generally in spring or early summer (NovemberDecember), and ascospore release begins in May in response to winter rainfall, which also stimulates the emergence of oilseed rape seedlings (McGee 1977). McGee and Petrie (1979) determined patterns of ascospore discharge in Victoria, Australia, using a Burkard spore trap, continuously sampling air at the rate of 10 l min −1 onto slides coated with ovalbumin. when temperature was 8-12°C and rainfall >1 mm (McGee and Petrie 1979).…”

Section: Introductionmentioning

confidence: 99%

“…McGee and Petrie (1979) determined patterns of ascospore discharge in Victoria, Australia, using a Burkard spore trap, continuously sampling air at the rate of 10 l min −1 onto slides coated with ovalbumin. when temperature was 8-12°C and rainfall >1 mm (McGee and Petrie 1979). Salam et al (2003) reported that ascospore release in Western Australia began at an hourly rainfall of >2 mm.…”

Section: Introductionmentioning

confidence: 99%

Maturation of pseudothecia and discharge of ascospores of Leptosphaeria maculans on oilseed rape stubble

2009

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The effects of temperature, wetness and darkness on formation of pseudothecia and the effect of temperature on the release of ascospores of L. maculans on oilseed rape stubble were studied in a controlled environment in South Australia. Pseudothecia of L. maculans developed at 5-20°C and the time taken to reach maturity and discharge ascospores decreased from 58 days at 5°C to 22.2 days at 15°C.The optimum temperature of those tested for pseudothecium maturation was between 15°C and 20°C but fewer pseudothecia were observed at 20°C than at 15°C. Exposure to a 12 h photoperiod enhanced pseudothecium formation on the stubble compared with continuous darkness. No pseudothecia formed on stubble moistened once a day at 15°C, whereas three sprays of water per day decreased maturation time in comparison with two sprays per day. More ascospores were released for a longer duration at 20°C than at 5-15°C, although peak sporulation occurred earlier at 5-10°C than at 20°C. These findings highlight the importance of moisture, temperature and light for production and release of inoculum from stubble. This information, combined with field data, may help to predict the onset of inoculum release.

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Diseases of Rapeseed (Canola) and Mustard

Nyvall¹

1989

Field Crop Diseases Handbook

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Seasonal Patterns of Ascospore Discharge byLeptosphaeria maculansin Relation to Blackleg of Oilseed Rape

Cited by 50 publications

References 0 publications

Epidemiology and management of Leptosphaeria maculans (phoma stem canker) on oilseed rape in Australia, Canada and Europe

Epidemiology and management of Leptosphaeria maculans (phoma stem canker) on oilseed rape in Australia, Canada and Europe

Maturation of pseudothecia and discharge of ascospores of Leptosphaeria maculans on oilseed rape stubble

Diseases of Rapeseed (Canola) and Mustard

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