Mycosphaerella Pinodes II. The Phenology of Ascospore Release

Carter, MV

doi:10.1071/bi9630800

Cited by 23 publications

(11 citation statements)

References 11 publications

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“…It is possible that when numerous crops of ascospores are released within the canopy as secondary inoculum, as occurred in 2009, the pathogen in the subsequent stubble is depleted and produces fewer ascospores as primary inoculum in the following autumn. Field pea residues are known to develop successive crops of mature pseudothecia, initially prolific, exhausting the inoculum by 50 weeks (Carter, ; McDonald & Peck, ).…”

Section: Discussionmentioning

confidence: 99%

Relationship between ascochyta blight on field pea (Pisum sativum) and spore release patterns of Didymella pinodes and other causal agents of ascochyta blight

et al. 2013

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Ascochyta blight of field pea, caused by Didymella pinodes, Phoma medicaginis var. pinodella, Phoma koolunga and Didymella pisi, is controlled through manipulating sowing dates to avoid ascospores of D. pinodes, and by field selection and foliar fungicides. This study investigated the relationship between number of ascospores of D. pinodes at sowing and disease intensity at crop maturity. Field pea stubble infested with ascochyta blight from one site was exposed to ambient conditions at two sites, repeated in 2 years. Three batches of stubble with varying degrees of infection were exposed at one site, repeated in 3 years. Every 2 weeks, stubble samples were retrieved, wetted and placed in a wind tunnel and up to 2500 ascospores g À1 h À1 were released. Secondary inoculum, monitored using seedling field peas as trap plants in canopies arising from three sowing dates and external to field pea canopies, was greatest in early sown crops. A model was developed to calculate the effective number of ascospores using predictions from G1 BLACKSPOT MANAGER (Salam et al., 2011b; Australasian Plant Pathology, 40, 621-31), distance from infested stubble (Salam et al., 2011a; Australasian Plant Pathology, 40, 640-7) and winter rainfall. Maximum disease intensity was predicted based on the calculated number of effective ascospores, soilborne inoculum and spring rainfall over two seasons. Predictions were validated in the third season with data from field trials and commercial crops. A threshold amount of ascospores of D. pinodes, 294 g À1 stubble h À1 , was identified, above which disease did not increase. Below this threshold there was a linear relationship between ascospore number and maximum disease intensity.

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Section: Discussionmentioning

confidence: 99%

Relationship between ascochyta blight on field pea (Pisum sativum) and spore release patterns of Didymella pinodes and other causal agents of ascochyta blight

et al. 2013

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“…It is evident that at least a proportion of the perithecia on the plants or plant debris receive sufficient moisture at any moment of the day for ascospore release. Carter (1963) suggested the same for Mycosphaerella pinodes on pea. Fletcher and Preece (1966) and Schenck (1968a) reported a similar peak concentration of ascopores of D.bryoniae in the evening hours with cucumbers in glasshouses and with watermelons outdoors, respectively.…”

Section: Discussionmentioning

confidence: 80%

“…Most probably rain has an effect on ascospore release but it could not be established under the experimental conditions outdoors. Rain favoured ascospore release of Mycosphaerella pinodes on pea straw and on days without rain ascospores were released in a regular daily rhythm with an afternoon peak too (Carter, 1963). According to the results in the growth chamber experiments a high relative humidity is not sufficient, a certain supply of moisture to the perithecia is needed for the release of ascospores.…”

Section: Discussionmentioning

confidence: 92%

Epidemiological aspects of Didymella bryoniae, the cause of stem and fruit rot of cucumber

Steekelenburg¹

1983

Netherlands Journal of Plant Pathology

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The survival of Didymella bryoniae and the incidence of ascospores in glasshouses, outdoors and under controlled conditions were studied. The fungus was able to overwinter in the open as dormant mycelium. Dry and undecomposed crop residues remained a source of infection for more than one year. Moisture and a minimum temperature between 5 and 10 ~ were needed for fructification. For ascospore release a high relative humidity was not sufficient, the substrate had to be moist during a short period. Ascospores could be trapped throughout day and night both outdoors and in glasshouses, but there was a marked peak during a period of 3 h in the evening. Both on days with and without rain about the same numbers of ascospores : were trapped from crop residues in the open. Ascospore release was favoured by watering the plants in the glasshouse. Under controlled conditions the release of ascospores was determined by humidity and not by light or darkness.In a cucumber crop in the glasshouse the first ascospores were trapped at about the same time the first symptoms on the plants appeared. In the glasshouse with introduced diseased plant debris, particularly when the debris became wet when the plants were watered, the disease was more severe and yield was less than in a glasshouse without introduced plant debris. Airborne ascospores may cause the primary infection of a cucumber crop. Therefore, hygienic measures must be taken to eliminate plant debris as source of infection, both in glasshouses and outdoors.

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“…This work contributed greatly to an understanding of the epidemiology of the disease. He established the pattern of ascospore release by Mycosphaerella pinodes (Carter 1961(Carter , 1963Carter and Moller 1961), was promoted to Senior Lecturer in 1963 and was awarded a PhD for his work by the University of Adelaide in 1964. He contributed to the development of the Burkard Seven Day Recording Volumetric Spore Trap and the Burkard Quadruple Ascospore Liberation Tunnels.…”

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confidence: 99%