A comparison of thirteen d‐factors as potential biological control agents of <i>Ophiostoma novo‐ulmi</i>

Sutherland, M.; Brasier, C. M.

doi:10.1046/j.1365-3059.1997.d01-62.x

Cited by 26 publications

(11 citation statements)

References 30 publications

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“…Variations in tree susceptibility related to different growth rhythms, caused by either seasons or differences in elm populations or clones (Sutherland & Brasier 1997), fit well with the growth-differentiation balance hypothesis (Herms & Mattson 1992). This hypothesis provides a framework for predicting how plants balance resource allocation between differentiation-related processes and growth-related processes over a range of environmental conditions, as it is known that resources cannot be allocated to both functions simultaneously (Lorio 1986).…”

Section: Host Resistancesupporting

confidence: 57%

Dutch elm disease and elm bark beetles: a century of association

Santini¹,

Faccoli²

2015

iForest

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Section: Host Resistancesupporting

confidence: 57%

Dutch elm disease and elm bark beetles: a century of association

Santini¹,

Faccoli²

2015

iForest

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“…In addition, it has a dispersion phase on a large scale during the period of its shoot feeding [28]. The slow growth rate and low levels of virulence of some isolates might be due to infections by mycoviruses, as already reported for Ophiostoma novo-ulmi and O. ulmi [39]. This possibility deserves further studies in the future.…”

Section: Variations In Growth and Virulence Between Isolates Of L Wimentioning

confidence: 66%

Variations in growth and virulence of Leptographium wingfieldii Morelet, a fungus associated with the bark beetle Tomicus piniperda L.

Lieutier¹,

Yart²,

Ye³

et al. 2004

Ann. For. Sci.

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-Growth and virulence of various isolates of Leptographium wingfieldii Morelet, isolated from Tomicus piniperda L. and galleries initiated by this insect on Scots pine (Pinus sylvestris L.) at different parts of the forest of Orléans, were compared. Six isolates were tested in 1994 and 15 in 1995. The tested parameters included the growth on malt agar at different temperatures, the ability of the fungus to stimulate the hypersensitive reaction in the phloem and to grow into the reaction zone after isolated inoculations of Scots pine trees, as well as fungal virulence to Scots pine after mass inoculations. Significant differences between isolates were observed for all parameters. These differences mainly refer to gradual variations among isolates, even though some isolates were constantly opposed to each other for all or most parameters. No obvious effect of the locality, from where the isolates had been obtained, was detected. The results suggest that the population of L. wingfieldii in the forest of Orléans consists of isolates that possess a high individual variability in growth characteristics and virulence to their host tree. Fungal growth both on malt agar and in the phloem was positively correlated with the length of the reaction zone in the phloem after isolated inoculations and with parameters related to fungal virulence after mass inoculations. Likewise, length of the reaction zone in the phloem was positively correlated to the number of killed trees and the percentage of blue stained sapwood area after mass inoculations. The results are discussed in relation to the possible origin of the variability in fungal growth and virulence, and to practical use of fungal growth on malt agar and in the phloem for screening and comparing the virulence of various isolates within the same blue stain fungal species.Leptographium wingfieldii / Tomicus piniperda / intraspecific variability / growth / virulence / tree defense reaction / temperature / Orléans Résumé -Variabilité de la croissance et de la virulence de Leptographium wingfieldii Morelet, champignon associé au Scolyte Tomicus piniperda L. La croissance et la virulence de divers isolats de Leptographium wingfieldii Morelet, isolés d'adultes de Tomicus piniperda L. et de leurs galeries provenant d'attaques récentes sur des pins sylvestres (Pinus sylvestris L.) dans différentes zones de la forêt d'Orléans, ont été comparées. Six isolats ont été considérés en 1994 et 15 en 1995. Les paramètres testés étaient la vitesse de croissance sur malt agar à diverses températures, la capacité du champignon à stimuler la réaction hypersensible du liber et à croître dans la zone de réaction après inoculations ponctuelles à des pins sylvestres, et sa virulence après inoculations massives sur Pin sylvestre. Des différences significatives entre isolats ont été observées pour tous les paramètres. Elles correspondent essentiellement à des variations graduelles, même si certains isolats étaient constamment opposés les uns aux autres pour tous ou la plupart des paramètres...

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“…During the 1980s, O. ulmi was shown to carry deleterious, cytoplasmically transmitted viruses (d‐factors) very similar to those in O. novo‐ulmi (Brasier, , ; Buck et al ., ). These can markedly decrease mycelial growth and conidial viability, reducing the potential for elm infection via the beetle feeding wounds (Brasier, ; Webber, ; Sutherland & Brasier, ). Moreover in O. ulmi , the viruses can be transmitted via the ascospores (L. Sutherland, Forest Research, Farnham, UK and C. M. Brasier, unpublished), a feature not observed in O. novo‐ulmi (Brasier, ) and one which would have limited the ability of O. ulmi to restrict virus spread.…”

Section: Discussionmentioning

confidence: 99%

“…Mycoviruses (then termed d‐factors) probably acquired from O. ulmi (Buck et al ., ) reached a high frequency in O. novo‐ulmi clones at epidemic fronts (Brasier, , ; Hong et al ., ; Brasier et al ., ). By reducing conidial viability and mycelial growth, the viruses can prevent O. novo‐ulmi from infecting elms via beetle feeding wounds (Webber, ; Sutherland & Brasier, ). However, following the acquisition of Vic loci and the MAT A locus from O. ulmi , numerous new O. novo‐ulmi vc types appeared and overt virus infections declined rapidly and remain infrequent today (Brasier, , ; Brasier et al ., ; Paoletti et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Is there evidence for post‐epidemic attenuation in the Dutch elm disease pathogenOphiostoma novo‐ulmi?

Brasier

Webber

2019

Plant Pathology

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The first pandemic of Dutch elm disease (DED) in Europe and North America caused by the introduced Ophiostoma ulmi began in the early 1900s but declined unexpectedly in Europe from the 1930s onwards after killing 30–40% of the elms. Later a second pandemic caused by the much more aggressive Ophiostoma novo‐ulmi spread across the same areas and by 1990 most of Britain's c. 30 million mature elms had died. During the second pandemic, O. novo‐ulmi acquired debilitating viruses and changed from being largely clonal to highly heterogeneous through horizontal transfer of novel, sometimes deleterious, genes from O. ulmi. In the post‐epidemic period a new disease dynamic has emerged, with millions of small recruitment elms repeatedly attacked by sequential cycles of disease. This study investigated the possibility of pathogenic attenuation in O. novo‐ulmi as the epidemic has progressed. Isolates collected from the three original outbreak areas in Britain in 1982–3 (early post‐epidemic period) and 2011 (advanced post‐epidemic) were compared for two fitness components: pathogenic aggressiveness and in vitro growth rate. Mean aggressiveness of the 2011 isolates to clonal English elm (Ulmus procera) proved not to differ significantly from that of the 1982 isolates, either overall or within each outbreak area. Similarly, the mean growth rates of the 1982 and 2011 samples showed no differences. The implications of these findings are discussed in relation to the future of the current DED pandemic in Europe, the decline of the first pandemic, and the difficulty of drawing parallels between different tree–pathogen systems.

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A comparison of thirteen d‐factors as potential biological control agents of Ophiostoma novo‐ulmi

Cited by 26 publications

References 30 publications

Dutch elm disease and elm bark beetles: a century of association

Dutch elm disease and elm bark beetles: a century of association

Variations in growth and virulence of Leptographium wingfieldii Morelet, a fungus associated with the bark beetle Tomicus piniperda L.

Is there evidence for post‐epidemic attenuation in the Dutch elm disease pathogenOphiostoma novo‐ulmi?

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