Estimating germinability ofPlasmopara viticola oospores by means of neural networks

Vercesi, A.; Sirtori, Cesare R.; Vavassori, Andrea; Setti, E.; Liberati, Dario

doi:10.1007/bf02344698

Cited by 13 publications

(12 citation statements)

References 3 publications

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“…The particularly dry and warm weather conditions recorded during the differentiation period in 2003 in M and T vineyards probably induced many oospores to degenerate, leading to the very low germination percentages observed in both samples. Germination is also influenced by the overwintering conditions, in particular the distribution and amount of rain 19. The very similar germination percentages observed in Montorio, except for 2003, seem to be related to the comparable amount and frequency of rain recorded in the vineyard during autumn and winter.…”

Section: Discussionmentioning

confidence: 76%

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Assessment of QoI resistance in Plasmopara viticola oospores

Toffolatti

Serrati²,

Sierotzki

et al. 2006

Pest Management Science

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QoI fungicides, inhibitors of mitochondrial respiration at the Qo site of cytochrome b in the mitochondrial bc(1) enzyme complex, are commonly applied in vineyards against Plasmopara viticola (Berk. & MA Curtis) Berl. & De Toni. Numerous treatments per year with QoI fungicides can lead to the selection of resistant strains in the pathogen population owing to the very specific and efficient mode of action. In order to evaluate the resistance risk and its development, two different methods, biological and molecular, were applied to measure the sensitivity of oospores differentiated in vineyards, both treated and untreated with azoxystrobin, from 2000 to 2004. Assays using oospores have the advantage of analysing the sensitivity of bulked samples randomly collected in vineyards, describing accurately the status of resistance at the end of the grapevine growing season. Both methods correlated well in describing the resistance situation in vineyards. QoI resistance was not observed in one vineyard never treated with QoI fungicides. In the vineyard where azoxystrobin had been used in mixture with folpet, the selection of QoI-resistant strains was lower, compared with using solely QoI. In vineyards where QoI treatments have been stopped, a decrease in resistance was generally observed.

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Section: Discussionmentioning

confidence: 76%

“…Berl. & De Toni and P. viticola 19–22. On water agar the germination percentages of oospores collected in Northern Italy vineyards varied depending on the location and the year of sampling.…”

Section: Discussionmentioning

confidence: 99%

Assessment of QoI resistance in Plasmopara viticola oospores

Toffolatti

Serrati²,

Sierotzki

et al. 2006

Pest Management Science

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“…To the best of our knowledge, most of the efforts to model germination dynamics have assumed that only exogenous factors affect oospore germination. Different modelling approaches, ranging from regression (Rossi et al 2002), mechanistic (Rossi et al 2008a), neural networks (Vercesi et al 2000), to fuzzy-neural models (Guglielmann et al 2002), have recently been explored, and resulted in models that reconstruct the dynamics from temporal series of environmental and climatic variables, and are exploited to simulate either downy mildew primary infections or germination rates. Such models have limited predictive performance, and do not give any insight into the complex processes responsible for germination, since they do not consider the biological mechanisms underlying oospore germination and metabolic processes needed for macrosporangium formation.…”

Section: Introductionmentioning

confidence: 99%

“…Numerous investigations, carried out by directly assessing oospore germination percentages on water agar at 20°C from November until July, suggested that macrosporangium formation persists from mid-end November until the end of May, less frequently until the middle of June and sporadically until the end of June (Toffolatti 2007). Regular rainfall distribution usually has a positive effect on oospore germination rates, but abundant rain events were seldom associated with strong decrease in oospore germination percentages (Vercesi et al 2000).…”

Section: Introductionmentioning

confidence: 99%

A new approach to modelling the dynamics of oospore germination in Plasmopara viticola

et al. 2010

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Oospores, the only overwintering structures of Plasmopara viticola, the causal agent of grapevine downy mildew, are the unique source of inoculum for primary infections in vineyards. We show that their germination dynamics depend on both climatic and endogenous factors. In particular, overwintering in controlled conditions suggests that low temperatures prolong the oospore germinability, while constant or gradually alternating water availability increases germination rates. However, wide fluctuations in germination percentage, observed both in naturally overwintered oospores, and under controlled conditions, indicate an important role for endogenous factors in the germination frequency. Ad hoc experimental assays and microscopic observations highlight an important role for calcium in the germination process. However, for a profound understanding of the biological mechanisms underlying oospore germination, mathematical models of the germination dynamics are needed. But, classical differential models of germination dynamics are, with current knowledge, prohibitive due both to the complexity of the underlying processes and knowledge incompleteness. Then, we propose a hybrid method derived from the integration of qualitative differential models and fuzzy systems.

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“…The sexual structures of the pathogen are differentiated in the infected leaves at the end of the grapevine growing season. They overwinter and germinate the following season, providing inoculum for primary infections (Vercesi et al 2000). QoI resistance is inherited maternally (Gisi et al 2002); therefore, QoI resistance can be studied in oospores collected at the end of the grapevine growing season, reflecting the result of the selection imposed by the fungicide applications made during the past season, and indicating the potential frequency of resistance in the primary inoculum for the following season.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Qol resistance in Plasmopara viticola oospores

Toffolatti

Prandato

Serrati³

et al. 2010

Eur J Plant Pathol

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QoI resistance in P. viticola was first detected in France and Italy in 1999. Molecular and biological assays have been carried out since 2000 in order to provide reliable methods of detecting and quantifying resistance. Oospores were collected in vineyards located in northern and southern Italy. QoI resistance was evaluated by the germination rate of oospores on azoxystrobin amended medium and the frequency of mutant alleles in the DNA extracted from oospores. Both methods correlated to each other and were used side by side to test QoI resistance. Due to the spontaneous occurrence of the G143A mutation in wild type populations and the immigration from surrounding vineyards, resistance frequencies up to 10% were found in samples collected from vineyards never treated with QoIs. Particularly high values, about 90%, were associated with the application of five to six QoI treatments within the same season, while lower percentages, about 30%, were detected in vineyards treated with QoI used in mixture with fungicides belonging to a different resistance group. A progressive decrease of resistance frequency was observed when QoI applications were reduced in number or completely suspended for at least one season. Therefore, a full recovery of sensitivity may be achieved even in vineyards characterized by high levels of resistance, if particular care is taken during disease control by using QoIs only in mixtures and reducing the number of QoI treatments.

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Estimating germinability ofPlasmopara viticola oospores by means of neural networks

Cited by 13 publications

References 3 publications

Assessment of QoI resistance in Plasmopara viticola oospores

Assessment of QoI resistance in Plasmopara viticola oospores

A new approach to modelling the dynamics of oospore germination in Plasmopara viticola

Evolution of Qol resistance in Plasmopara viticola oospores

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