A Conducive Day Concept to Explain the Effect of Low Temperature on the Development of Scleroderris Shoot Blight

Marosy, M.; Patton, R. F.; Upper, Christen D.

doi:10.1094/phyto-79-1293

Cited by 47 publications

(38 citation statements)

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“…The NA race produces ascospores that are responsible for longdistance fungus spread (Skilling et al 1986). It could not corne from the residual infected red pines because ail those trees had been pruned at a height of 2 m prior to the jack pine plantation, and it is known that the NA race can only infect its hosts in the snow, usually less than 2 m above the ground (Marosy et al 1989). Jack pine is not killed by the EU race even when trees are showing a high frequency of tip blight (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…The NA race is believed to be indigenous to this continent based on its wide distribution, its ecological adaptations and the high levels of genetic variability (Hamelin et al 1993;Laflamme 1993). The NA race only infects pine shoots thatare undersnowcover (Marosy et al 1989), thus only seedlings or lower tree branches of a tree are affected. The EU race also begins by infecting shoots on the lower part of the tree but it can subsequently develop in the upper crown of large trees, thereby causing more damage than the NA race.…”

Section: Introductionmentioning

confidence: 99%

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Resistance of Pinus banksiana to the European race of Gremmeniella abietina

Laflamme¹,

Blais²

2005

phyto

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Au début des années 80, plus de 90 % de mortalité causée par Gremmeniella abietina, race européenne, a été relevée dans des plantations de pin rouge (Pinus resinosa) localisées à environ 200 km au nord-ouest de Montréal, Québec, Canada. Les pins gris ( Pinus banksiana) avoisinants ne semblaient pas attaqués. Les forestiers ont donc reboisé ces aires avec des semis de pin gris. Des parcelles d'études de 100 pins gris ont été établies dans trois plantations sur les quatre sélectionnées en 1988. Comme références, des semis de pin rouge ont été plantés dans des conditions semblables dans la quatrième plantation en 1989. Les observations annuelles se sont déroulées de 1989 à 1992. La mortalité des semis de pin rouge atteignait 70 % en 1992 alors que les pins gris des trois sites expérimentaux n'étaient pas attaqués, à l'exception d'une brûlure à l'extrémité des pousses, caractéristique qui permet d'identifier la race au champ. Les symptômes de la race nord-américaine étaient présents à un taux très bas; leur incidence a augmenté sur le site I en 1992. Plus de 10 ans après la plantation, les pins gris montrent une résistance à la race européenne de G. abietina alors que tous les pins rouges sont morts.In the early 1980s, more than 90% of mortality caused by Gremmeniella abietina, European race, was recorded in red pine (Pinus resinosa) plantations 200 km northwest of Montreal, Quebec, Canada. Surrounding jack pines (Pinus banksiana) did not appear to be affected. Consequently, foresters began to plant the affected areas with jack pine seedlings. In 1988, plots of 100 jack pines were established in three of the four selected plantations. As reference, red pine seedlings were planted in 1989 under similar conditions in the fourth plantation. Observations were carried out annually from 1989 to 1992. Mortality of red pine seedlings reached 70% in 1992 while all jack pines on the three experimental sites were free of the disease except for a tip blight, a distinctive feature allowing race identification in the field. The North American race symptoms were present at a very low incidence, but began to increase on site I in 1992. More than 10 years after planting, the jack pine trees still show resistance to the European race of G. abietina while all the red pines died

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resistance of Pinus banksiana to the European race of Gremmeniella abietina

Laflamme¹,

Blais²

2005

phyto

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“…After February there was only eight more conducive days. As the lesion lengths for January inoculations in August were not significantly different from controls it seems likely that only the December inoculations were performed within the susceptibility period predicted by the conducive day concept (Marosy et al, 1989). Alternatively, the 3.8-fold difference in mean lesion lengths (22 vs. 5.8 mm) could be explained by a 2.6-fold difference in degreedays above 5 °C (26 vs. 9.9).…”

Section: Discussionmentioning

confidence: 93%

“…unable to defend themselves. (RollHansen, 1964;Blenis et al, 1984;Barklund and Unestam, 1988;Marosy et al, 1989;Karlman et al, 1994, Terho andUotila, 1999). Although spore dispersal and infection of the host occur during the growing season, G. abietina is able to grow into the living host tissues firstly during host dormancy .…”

Section: Discussionmentioning

confidence: 99%

“…Although spore dispersal and infection of the host occur during the growing season, G. abietina is able to grow into the living host tissues firstly during host dormancy . In an inoculation experiment using conidiospores, Marosy et al (1989) found that a period of at least 44 conducive days, i.e. days with temperatures remaining between -6 and +5 °C, was necessary for symptom development.…”

Section: Discussionmentioning

confidence: 99%

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Susceptibility of Pinus nigra and Cedrus libani to Turkish Gremmeniella abietina isolates

2012

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Gremmeniella abietina causes shoot dieback and stem cankers on conifers throughout Northern hemisphere. The aim of this study was to investigate the virulence of Turkish G. abietina isolates in a field experiment.The lower branches of 15-20-year-old P. nigra and C. libani in a plantation site at 1,050 m a.s.l. in Isparta were inoculated at 1-2-month intervals during September-January. Five isolates obtained from high altitude mountainous forests were used. Each isolate was inoculated into two branches per tree and repeated ten times on both tree species at each inoculation date. The branches were sampled at the end of February, and in August, and lesion lengths in the inner bark measured.The mean lesion length on P. nigra and C libani were 10.6 ± 0.8 and 3.8 ± 0.2 mm in February and 17.6 ± 1.4 and 7.8 ± 0.8 mm in August, respectively.Differences in the mean lesion length between the isolates were small. Nevertheless, there were significant differences between the isolates on P. nigra in November and January inoculations, and on C. libani at all four inoculation times.The mean lesion lengths for all isolates at both sampling dates was the highest (p < 0.01) in December inoculations for both P. nigra (22.0 ± 1.9 February; 32.9 ± 2.9 August) and C. libani (5.6 ± 0.7; 11.3 ± 1.2). There was no difference between the September and January inoculations on P. nigra, despite the almost six-fold difference in incubation period. During the December inoculations, the trees were most likely in winter dormancy, i.e. unable to defend themselves, which would explain the large lesions.

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