Release, germination, and pathogenicity of ascospores of <i>Uncinula necator</i> under controlled conditions

Jailloux, F.; Thind, T. S.; Clerjeau, Michel

doi:10.1139/b98-054

Cited by 17 publications

(18 citation statements)

References 6 publications

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“…Ascospore infections have been confirmed for only a limited number of species (Braun, 1995;Jailloux et al, 1998;Mmbaga, 2000;Pearson and Gadoury, 1987). Our results demonstrate that for oak powdery mildew, ascospores released by chasmothecia can be a major source of primary inoculum in spring.…”

Section: Discussionmentioning

confidence: 62%

Variabilité phénotypique dans la phénologie de la production d’ascospores entre populations européennes d’oïdium du chêne

Marçais¹,

Kavkova²,

Desprez‐Loustau³

2009

Ann. For. Sci.

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Abstract• Oak powdery mildew severity (Erysiphe alphitoides) is usually mild in Europe because epidemics start late in spring, at the end of the first oak growth unit maturation. However, the disease can occasionally be very severe when strong infection occurs early during the development of the first growth unit, suggesting that host-pathogen synchrony in spring could be a critical factor in disease severity.• We studied the timing of ascospore production in a given environment for four E. alphitoides populations sampled from SW France to the Czech Republic to determine whether this trait shows variation within Europe.• Timing of ascospore production was clearly influenced by environmental factors as chasmothecia from a single origin showed very different dates of optimal ascospore production when transferred for overwintering in locations with different climate. In common garden experiments, no differences were observed between populations for the date of optimal ascospore production.• Results suggest little genetic differentiation for timing of ascospore production for E. alphitoides populations across Europe and therefore a lack of local adaptation to their host phenology. Availability in ascospore inoculum is limited during host budburst, explaining the low infection usually observed on the first oak growth unit. Mots-clés :agent pathogène / arbre forestier / Erisyphe alphitoides / Quercus / synchronisation Résumé -Variabilité phénotypique dans la phénologie de la production d'ascospores entre populations européennes d'oïdium du chêne.• L'oïdium du chêne (Erysiphe alphitoides) est généralement peu sévère en Europe, la maladie se développant tard au printemps, après le débourrement des chênes. E. alphitoides peut toutefois être sévère quand de fortes infections se produisent tôt durant le débourrement, suggérant que la synchronisation entre hôte et pathogène pourrait être un facteur déterminant la sévérité des épidémies.• Nous avons caractérisé la dynamique de production d'ascospores dans un environnement donné pour quatre populations d'E. alphitoides échantillonnées du sud-ouest de la France à la République Tchèque pour tester si ce trait est variable en Europe.• Des chasmothèces d'une même origine présentent des dates d'optima de production d'ascospores très différentes quand elles sont transférées durant l'hiver dans des zones à climats différents montrant que ce trait est sous dépendance de l'environnement. Par contre, les quatre populations ont la même date d'optimum de production d'ascospores quand elles sont placées dans un même environnement.• Les résultats suggèrent que les populations d'E. alphitoides européennes ne sont pas différentiées génétiquement pour le timing de production d'ascospores et donc qu'elles ne sont pas localement adaptées à la phénologie de leur hôte. L'inoculum ascospores est très peu présent durant le débourre-ment, expliquant en partie l'absence d'infection sur la première unité de croissance des chênes.

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Section: Discussionmentioning

confidence: 62%

Variabilité phénotypique dans la phénologie de la production d’ascospores entre populations européennes d’oïdium du chêne

Marçais¹,

Kavkova²,

Desprez‐Loustau³

2009

Ann. For. Sci.

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“…Infection is significantly reduced at 15°C or below. No infection occurs at or below 5°C, nor does it occur at or above 31 oc (Gadoury & Pearson, 1990b;Pearson, 1990;Jailloux et al, 1998).…”

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confidence: 99%

Cleistothecia and Flag Shoots: Sources of Primary Inoculum for Grape Powdery Mildew in the Western Cape Province, South Africa

Halleen

Holz

2017

SAJEV

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“…Their work demonstrated that ascocarps, known as chasmothecia (formerly cleistothecia), survive winter and release ascospores the next spring, and that these ascospores serve as primary inoculum. Afterwards, several studies reported that chasmothecia have a role in the overwintering of the fungus and in the outbreak of powdery mildew epidemics in several grape-growing areas (Gadoury & Pearson, 1988;Cortesi et al, 1997;Magarey et al, 1997;Jailloux et al, 1998;Schneider et al, 1998;Steinkellner & Redl, 1998;Halleen & Holz, 2000;Hoffmann & Vir anyi, 2007;Rossi et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

A model for the development of Erysiphe necator chasmothecia in vineyards

2013

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A temperature-driven, mechanistic model predicting the development of Erysiphe necator chasmothecia in vineyards was developed and validated in 38 vineyards in the Po Valley (northern Italy), Baden-W€ urttemberg (Germany), and South Australia between 2005 and 2011. The model, which begins operating when the first ascocarp initials are formed, predicts on a daily basis the proportions of chasmothecia at the yellow, brown and black maturity stage. The initialization date was estimated with an iterative procedure that minimized the residuals of predicted versus observed values. In all vineyards, a drop to more favourable temperatures for ascocarp production over 2-4 days in the week or in the 2 weeks before the model initialization date probably triggered chasmothecia production. Model predictions provided a good fit of observed data (coefficients of determination, model accuracy, efficacy and efficiency were all ≥0Á90), with some overestimation. When predicted production of black chasmothecia (on leaves) was compared with observed dispersal of chasmothecia from vines, lack of splashing rain was probably the main cause of overestimation. When observed numbers of yellow, brown or black chasmothecia on leaves were compared with model predictions, removal of the developing chasmothecia by rainfall was probably the main cause of overestimation. Inclusion of the effect of rainfall on the removal of immature and mature chasmothecia from the powdery mildew colonies could improve the model. The model could be used to time the application of fungicides or biocontrol agents for reducing ascocarp formation and reducing primary inoculum in the following season.

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Release, germination, and pathogenicity of ascospores of Uncinula necator under controlled conditions

Cited by 17 publications

References 6 publications

Variabilité phénotypique dans la phénologie de la production d’ascospores entre populations européennes d’oïdium du chêne

Variabilité phénotypique dans la phénologie de la production d’ascospores entre populations européennes d’oïdium du chêne

Cleistothecia and Flag Shoots: Sources of Primary Inoculum for Grape Powdery Mildew in the Western Cape Province, South Africa

A model for the development of Erysiphe necator chasmothecia in vineyards

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