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Assessing crop diseases at an early stage allows farmers to apply chemicals at the most efficient moment to control the pest and focus on the plants with the highest risk of developing the disease. Moreover, the earlier the assessment the lower the consequences, such as yield reduction, which is crucial to feed the increasing world population. BBR is the first open-source software based on physical and phenological crop parameters that grant the early assessment of botrytis bunch rot disease, caused by Botrytis cinerea, in vineyards using UAV images. This software has been released to improve the current procedure for early botrytis bunch rot assessment, which consists of laborious and time-consuming field inspections. In addition, BBR is easily modifiable by users to implement the workflow in their fields. For future work, the software can be extended to other crops and/or other fungal diseases.

In organic phytosanitary management of vineyards, it is crucial to understand the available pathogen control alternatives in order to progress towards a more sustainable form of viticulture. The objective of this study was to evaluate the efficacy of seven biofungicides registered in Chile for the prevention and treatment of Botrytis Bunch Rot (BBR), and to test a novel fungicide composed of chitosan and riboflavin (CH-RF). Biofungicides including Trichoderma spp., Aureobasidium pullulans, and Melaleuca alternifolia were evaluated using biotests with grapevine berries. Registered products (specifically biological control agents) significantly reduced the in vitro growth of B. cinerea. However, the degree of pathogen control varied significantly among products in grapevine berries of the Chardonnay cultivar, and disease incidence and severity changed depending on the inoculation time. High control effectiveness was achieved with two biofungicides, A. pullulans (average efficacy 34%) and M. alternifolia oil (average efficacy 29%). In vitro tests showed CH-RF significantly reduced mycelial growth of B. cinerea. Noticeable differences between the new CH-RF fungicide (incidence under 50% and infection score under 1) and A. pullulans- and M. alternifolia-based products were detected in grapevine berries. Therefore, the new experimental formulation CH-RF constitutes a promising alternative for the control of B. cinerea and provides a basis for further research. [ABSTRACT FROM AUTHOR]

Eugenol (2-methoxy-4-(2-propenyl)-phenol), widely spread in various plants, notably clove, basil and bay, is a well-known antifungal and antibiotic molecule that is abundant in the hybrid grapevine cultivar Baco blanc (Vitis vinifera × Vitis riparia × Vitis labrusca). This variety, created by François Baco (19th century), is confirmed in this study as highly resistant to Botrytis cinerea by comparing fruit rot incidence and severity with two Vitis vinifera cultivars: Folle Blanche and Ugni Blanc. According to two major antibiosis modes of action, i.e., direct or volatile, this study demonstrated the efficiency of eugenol in vitro by also investigating precisely the effect on B. cinerea of small concentrations of eugenol, 3 to 4 ppm, corresponding to IC10. Moreover, the vapour-inhibiting effect was shown to be highly powerful. The total eugenol concentration peaked at the veraison stage, exceeding 1000 μg×kg-1 in the skin of Baco blanc berry under our conditions. At this point, leaf removal in the bunch zone induced a significant increase in eugenol (32 %), from 1118 to 1478 μg×kg-1, which was also associated with a significant decrease in B. cinerea infection in the vineyard. Thus, for the first time, eugenol, as an endogenous molecule of Baco blanc, was clearly demonstrated to be an inducible compound in the vineyard. Furthermore, significant intravarietal variability in eugenol concentrations according to the Baco blanc clone was demonstrated to be associated with significant differences in fruit susceptibility to the plant pathogen assessed in biotests. Interestingly, in keeping with fruit ontogenic resistance, a significant negative correlation was established between the technological maturity of berries and the total eugenol content in the berry skin. Finally, the time-progress study of the two biochemical forms of eugenol (bound vs. free eugenol) allowed us to hypothesise the effectiveness against the plant pathogen of some precursor forms of eugenol, and the corresponding biochemical structures are currently being investigated. Thus, eugenol appears to be a key biochemical marker of ontogenic resistance in the hybrid cultivar Baco blanc.

Botrytis bunch rot of grapes (BBR) causes substantial crop and wine quality issues globally. Past and present foundations for BBR control are based upon synthetic fungicides and varying forms of canopy management. Many authors regard the continued dependence on fungicides as unsustainable and have urged greater deployment of cultural, biological and nutritional strategies. However, in contrast to organic wine production, the uptake of alternative strategies in conventional vineyards has been slow based on cost and perceived reliability issues. This review summarises research from many different wine growing regions in New Zealand with the aim of demonstrating how traditional and newly developed cultural control practices have cost-effectively reduced BBR. In addition to reviewing traditional cultural practices (e.g., leaf removal), mechanical tools are described that remove floral trash and mechanically shake the vines. Multi-omics has improved our knowledge of the underlying changes to grape berries after mechanical shaking. Exogenous applications of calcium may correct calcium deficiencies in the berry skin and reduce BBR but the outcome varies between cultivar and regions. Nitrogen aids in grapevine defence against BBR but remains a complex and difficult nutrient to manage. The sustainable growth of organics and The European Green Deal will stimulate researchers to evaluate new combinations of non-chemical BBR strategies in the next decade. [ABSTRACT FROM AUTHOR]

In organic phytosanitary management of vineyards, it is crucial to understand the available pathogen control alternatives in order to progress towards a more sustainable form of viticulture. The objective of this study was to evaluate the efficacy of seven biofungicides registered in Chile for the prevention and treatment of Botrytis Bunch Rot (BBR), and to test a novel fungicide composed of chitosan and riboflavin (CH-RF). Biofungicides including Trichoderma spp., Aureobasidium pullulans, and Melaleuca alternifolia were evaluated using biotests with grapevine berries. Registered products (specifically biological control agents) significantly reduced the in vitro growth of B. cinerea. However, the degree of pathogen control varied significantly among products in grapevine berries of the Chardonnay cultivar, and disease incidence and severity changed depending on the inoculation time. High control effectiveness was achieved with two biofungicides, A. pullulans (average efficacy 34%) and M. alternifolia oil (average efficacy 29%). In vitro tests showed CH-RF significantly reduced mycelial growth of B. cinerea. Noticeable differences between the new CH-RF fungicide (incidence under 50% and infection score under 1) and A. pullulans- and M. alternifolia-based products were detected in grapevine berries. Therefore, the new experimental formulation CH-RF constitutes a promising alternative for the control of B. cinerea and provides a basis for further research.

Late-season bunch rot can cause substantial yield loss in grapevines grown in humid regions. Fruit-zone leaf removal has been widely used to reduce bunch rot and pesticide applications through improvements in canopy microclimate and grape cluster morphology. In this study, we evaluated whether mechanical leaf removal can be a valid alternative to a labor-intensive manual application by comparing prebloom manual (PB-MA) and mechanical (PB-ME) leaf removal. We also evaluated the effects of the timing of mechanical application, prebloom (PB-ME) versus fruit set (FS-ME), on fruit traits and bunch rot, caused by Botrytis cinerea . Our trials were conducted on two Vitis vinifera 'Pinot noir' and 'Pinot gris' vineyards in the Northeastern United States over two seasons (2017 to 2018). Major findings were overall consistent between cultivars and years. Leaf removal provided reductions in fruit-zone canopy density regardless of method or timing. In general, PB-ME provided similar shifts in cluster morphological traits to PB-MA, including lower number of berries per cluster, cluster compactness, and cluster weight compared with control (no leaf removal) vines. At harvest, both prebloom leaf removal methods equally reduced Botrytis bunch rot severity, whereas Botrytis bunch rot incidence in Pinot noir was lowest for PB-ME in 1 year and PB-MA in the next year. When comparing timing of mechanical leaf removal, FS-ME provided Botrytis bunch rot reductions similar to PB-ME, without effects on cluster weight. Thus, under our growing conditions, FS-ME was considered the best mechanical leaf removal option to help manage Botrytis bunch rot without causing undesirable yield reductions., Competing Interests: The author(s) declare no conflict of interest.

The presence and germination rate of Botrytis cinerea conidia on 'Sauvignon blanc' grape berries from Pukekohe, New Zealand, was determined over the 2010–11 and 2011–12 growing seasons by means of inoculated berries. Conidia on the inoculated berries were able to germinate and enter the grape berries at any time during the season, albeit at low rates during the early season. In both years, the proportion of germinated conidia increased with berry age/growth stage. Microscopic examinations revealed that B. cinerea conidia germinated on the grape berry surface and hyphae entered the berries directly either between adjoining cells, by penetrating directly through the cell wall, or via appressoria. Penetration of the grape berry surface was highly variable, with some germ tubes penetrating immediately beneath the conidium and others having extended germ tubes. While most germinated conidia appeared to penetrate the berry, a proportion were seen to germinate to form spermatia (phialomicroconidia). Conidial anastomosis (two conidia connected by a short germ tube) was seen on the surface of some berries. [ABSTRACT FROM AUTHOR]

Botrytis bunch rot of grapes (BBR) causes substantial crop and wine quality issues globally. Past and present foundations for BBR control are based upon synthetic fungicides and varying forms of canopy management. Many authors regard the continued dependence on fungicides as unsustainable and have urged greater deployment of cultural, biological and nutritional strategies. However, in contrast to organic wine production, the uptake of alternative strategies in conventional vineyards has been slow based on cost and perceived reliability issues. This review summarises research from many different wine growing regions in New Zealand with the aim of demonstrating how traditional and newly developed cultural control practices have cost-effectively reduced BBR. In addition to reviewing traditional cultural practices (e.g., leaf removal), mechanical tools are described that remove floral trash and mechanically shake the vines. Multi-omics has improved our knowledge of the underlying changes to grape berries after mechanical shaking. Exogenous applications of calcium may correct calcium deficiencies in the berry skin and reduce BBR but the outcome varies between cultivar and regions. Nitrogen aids in grapevine defence against BBR but remains a complex and difficult nutrient to manage. The sustainable growth of organics and The European Green Deal will stimulate researchers to evaluate new combinations of non-chemical BBR strategies in the next decade.

Еssеntial oils (ЕOs) from cinnamon (Cinnamon zylanicum), clovе (Syzygium aromaticum) camphor (Еucalyptus globulus), and rockеt (Еruca sativa), wеrе еvaluatеd for thеir botryocidal еffеct. In-vitro, Botrytis cinеrеa was еxposеd to 4 diffеrеnt concеntrations of ЕOs, using thrее diffеrеnt tеchniquеs, i.е. amеndеd mеdium, vapourisation, and volatilising. Cinnamon and clovе ЕOs wеrе thе highеst tеstеd concеntrations found to bе thе most еffеctivе in all tеchniquеs which complеtеly inhibitеd 100% of radial growth for B. cinеrеa in vitro. A post-harvеst trial to control grеy mould on grapе bunchеs of Flamе sееdlеss and Supеrior sееdlеss cvs. were conductеd using cinnamon and clovе oils in sеasons 2014 and 2015. Both of the two ЕOs wеrе usеd at concеntrations of 25, 50 and 100 µL./L-1air v/v, еxposеd as vapour trеatmеnt significantly supprеssеd grеy mould during thе cold-storagе. Thеrе was not a significancе diffеrеncеs obsеrvеd among both ЕOs trеatmеnts. Howеvеr, cinnamon at 100 µL.1L-1air v/v was thе most еffеctivе trеatmеnt to control grеy mould of both grapе cultivars

A real-time loop-mediated isothermal amplification (LAMP) assay was evaluated for the detection of Botrytis cinerea in grapevine bunch trash, immature berries, and ripening berries. A simple method for the preparation of crude extracts of grape tissue was also developed for on-site LAMP analysis. When tested with 14 other fungal species frequently found in grapevines, the LAMP assay was specific and sensitive to a B. cinerea DNA quantity of 0.1 ng/µL. The sensitivity was further tested using bunch trash samples with B. cinerea colonization levels between 6 and 100% and with bulk-berry samples composed of 4 pathogen-free berries or 4 berries among which 25 to 100% had been inoculated with B. cinerea. The LAMP assay detected the lowest B. cinerea colonization level tested in bunch trash and in immature and mature berries in less than 20 min. In single-berry experiments, LAMP amplified B. cinerea DNA from all artificially inoculated individual immature and mature berries. No amplification occurred in B. cinerea-free material. The real-time LAMP assay has the potential to be used as a rapid on-site diagnostic tool for assessing B. cinerea colonization in bunch trash and B. cinerea latent infections in berries, which represent critical stages for decision-making about disease management.

BACKGROUND: Control of Botrytis bunch rot (BBR) is currently based on the application of fungicides at four timings corresponding to specific growth stages of vines: end of flowering (A), pre‐bunch closure (B), veraison (C) and before harvest (D). The current research provides a network meta‐analysis of 116 studies conducted between 1963 and 2016 in nine countries, in which 14 strategies (based on combinations of 1, 2, 3, or 4 sprays applied in A, B, C, and/or D) were compared. RESULTS: When a one‐spray strategy was applied, BBR control was more effective with sprays applied in A, C, or D than B. With a two‐spray strategy, strategy AC provided similar control as strategy BC; strategy CD also provided good control. For a 3‐spray strategy, the best disease control was consistently obtained with strategy ACD. Four‐spray strategy ABCD provided the best control but often involved needless sprays so that the routine application of four sprays is not justified. CONCLUSIONS: Spraying at timing A seems to be very important for achieving efficient and flexible disease control. Flexibility is reduced by spraying at timing B rather than A. © 2018 Society of Chemical Industry Control of Botrytis bunch rot is currently based on fungicide application at four timings. This paper provides a quantitative review of 116 studies in which 14 strategies were compared. [ABSTRACT FROM AUTHOR]

In this study, prohexadione-Ca was applied at bloom and postbloom stages to field-grown cultivar Xinomavro to evaluate the effects on leaf chlorophyll content, water potential, photosynthesis, grape, berry size and composition and wine quality. The results showed that prohexadione-Ca increased the chlorophyll contents and net photosynthesis in early growth stages (berry set, veraison). Its effect was gradually reduced in later growth of stages. In addition, prohexadione-Ca affected the stomatal conductance mainly at later stage. In contrast, it did not show any effect on the water potential. It was also shown that the prohexadion - Ca reduced the berry size and increased skin anthocyanin and phenolic compounds. Wines provided from treated vines had improved colour and sensory attributes. Applications with prohexadione-Ca improved the resistance of grapes to Botrytis bunch rot in the first year of experiments. In contrast, no significant difference on susceptibility of grapes to Botrytis bunch rot was found in the second year of experiments. No effect of prohexadione-Ca on the susceptibility of vines to downy mildew and powdery mildew was found. [ABSTRACT FROM AUTHOR]

Еssеntial oils (ЕOs) from cinnamon (Cinnamon zylanicum), clovе (Syzygium aromaticum) camphor (Еucalyptus globulus), and rockеt (Еruca sativa), wеrе еvaluatеd for thеir botryocidal еffеct. In-vitro, Botrytis cinеrеa was еxposеd to 4 diffеrеnt concеntrations of ЕOs, using thrее diffеrеnt tеchniquеs, i.е. amеndеd mеdium, vapourisation, and volatilising. Cinnamon and clovе ЕOs wеrе thе highеst tеstеd concеntrations found to bе thе most еffеctivе in all tеchniquеs which complеtеly inhibitеd 100% of radial growth for B. cinеrеa in vitro. A post-harvеst trial to control grеy mould on grapе bunchеs of Flamе sееdlеss and Supеrior sееdlеss cvs. were conductеd using cinnamon and clovе oils in sеasons 2014 and 2015. Both of the two ЕOs wеrе usеd at concеntrations of 25, 50 and 100 μL./L-1air v/v, еxposеd as vapour trеatmеnt significantly supprеssеd grеy mould during thе coldstoragе. Thеrе was not a significancе diffеrеncеs obsеrvеd among both ЕOs trеatmеnts. Howеvеr, cinnamon at 100 μL.1L-1air v/v was thе most еffеctivе trеatmеnt to control grеy mould of both grapе cultivars. [ABSTRACT FROM AUTHOR]

Native yeasts are of increasing interest to researchers, grape growers, and vintners because of their potential for biocontrol activity and their contributions to the aroma, flavor, and mouthfeel qualities of wines. To assess biocontrol activity, we tested 11 yeasts from Washington vineyards, representing isolates of Candida saitoana, Curvibasidium pallidicorallinum, Metschnikowia chrysoperlae, M. pulcherrima, Meyerozyma guilliermondii, Saccharomyces cerevisiae, and Wickerhamomyces anomalus, for ability to colonize Thompson Seedless grape berries, inhibit the growth of Botrytis cinerea in vitro, and suppress disease symptoms on isolated berries. The yeast-like fungus Aureobasidium pullulans was also included based on its known biocontrol activity against B. cinerea in studies on apple and grape. All yeast strains multiplied rapidly in grape berries and reached densities of over log 6 cells per wound as early as 2 days after inoculation with 200 cells. One of the Botrytis isolates used in this study was much less virulent than the others and was provisionally identified as B. prunorum based on multilocus sequence analysis. Suppression of the growth of B. cinerea isolates 11 Ibb, 207a, 207cb, and 407cb occurred on berries treated with A. pullulans P01A006, Metschnikowia chrysoperlae P34A004 and P40A002, M. pulcherrima P01A016 and P01C004, Meyerozyma guilliermondii P34D003, and S. cerevisiae HNN11516. Inhibition of Botrytis isolates by the yeast strains was more common on berries than in vitro, suggesting the possibility that niche competition was a more likely biocontrol mechanism than antibiosis in planta. Metabolic profiling of yeast strains and B. cinerea isolates using Biolog YT plates revealed seven distinct metabolic groups. Furthermore, the yeast strains showed partial to complete tolerance to the commonly used fungicides fluopyram, triflumizole, metrafenone, pyraclostrobin, and boscalid. Implications of these findings for field deployment of native Washington yeasts as biocontrol agents against B. cinerea are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Background and Aims: The susceptibility of winegrape cultivars to Botrytis cinerea is a debated topic, and the available classifications are based on professional experience rather than on experimental data. The main aim of this study was to compare and classify the susceptibility of several winegrape cultivars to B. cinerea and its relation to fruit maturity under two contrasting climatic and cropping conditions. Methods and Results: Between 2011 and 2015, three field trials were undertaken in Chile and France, including 13 common cultivars. Both the incidence and severity of the disease were evaluated at harvest, and indices of susceptibility and maturity were calculated on a per site basis. The significant difference in incidence and severity observed among cultivars led to a similar susceptibility classification in both countries. Cabernet Sauvignon, Cabernet Franc, Grenache Noir and Petit Verdot were the most resistant cultivars, whereas Gewürztraminer and Sauvignon Blanc were the most susceptible. Moreover, an exponential and positive relationship was established between indexes of susceptibility and maturity. Conclusions: The classification of cultivars according to the susceptibility to B. cinerea was similar in both countries, despite the contrasting climatic conditions and cropping practices. Significance of the Study: These findings might be of interest for choosing cultivars that are more resistant to B. cinerea to reduce the number of fungicide applications. [ABSTRACT FROM AUTHOR]

Although the use of biocontrol agents (BCAs) to manage plant pathogens has emerged as a sustainable means for disease control, global reliance on their use remains relatively insignificant and the factors influencing their efficacy remain unclear. In this work, we further developed an existing generic model for biocontrol of foliar diseases, and we parametrized the model for the Botrytis cinerea−grapevine pathosystem. The model was operated under three climate types to study the combined effects on BCA efficacy of four factors: (i) BCA mechanism of action, (ii) timing of BCA application with respect to timing of pathogen infection (preventative vs. curative), (iii) temperature and moisture requirements for BCA growth, and (iv) BCA survival capability. All four factors affected biocontrol efficacy, but factors iii and iv accounted for > 90% of the variation in model simulations. In other words, the most important factors affecting BCA efficacy were those related to environmental conditions. These findings indicate that the environmental responses of BCAs should be considered during their selection, BCA survival capability should be considered during both selection and formulation, and weather conditions and forecasts should be considered at the time of BCA application in the field.

Bunch compactness (or density) is a grapevine specific trait that affects the commercial quality and sanitary status of wine and tablegrapes. Compact bunches are more susceptible to diverse pests and diseases such as Botrytis bunch rot and their berries ripen more heterogeneously, causing important economic losses through a reduction in crop yield and grape and wine quality. Bunch compactness is determined by the fraction of the morphological volume of the bunch that is filled by berries, but this simple definition contrasts sharply with the difficulty to measure it. While there are several objective and quantitative methods available to measure bunch compactness, the lack of a consistent approach between researchers makes comparing measurements difficult. The complexity of bunch compactness initially arises from the several bunch and berry traits that influence it, and from the distinct effects that these traits may cause in different cultivars. In addition to this genetic effect, diverse environmental signals impact on bunch compactness by affecting those primary factors that contribute to the solid component of the bunch (berry number, berry size) or to its spatial arrangement (rachis architecture). Last, several viticultural approaches, including agronomic techniques and growth regulators, have also proven to affect bunch compactness in different ways. This review aims to discuss present knowledge about this relevant grapevine trait. [ABSTRACT FROM AUTHOR]

Our paper offers unique information regarding the effects of DL-β-amino-n-butyric acid (BABA) on grape cluster compactness and Botrytis bunch rot development. The impact of treatment was investigated on a native Hungarian grapevine cultivar, 'Királyleányka' (Vitis vinifera L.) during three seasons. The highly sensitive cultivar with thin skinned berries provided excellent samples for Botrytis bunch rot studies. Our objective was to study if BABA treatment contributes to decrease Botrytis infection by promoting looser clusters. For this purpose, the female sterility effect of BABA in grapevine flowers was also examined, which may result in looser clusters. Cluster compactness was characterized with two different indexes; bunch rot incidence was assessed in percentages. Ovaries of flowers were examined under epifluorescent microscope. Significant differences were found in the compactness index (berry number/bunch length) between the control (2.87 ± 0.83 no./cm) and treated bunches in the case of 2.0 g·L-1 (2.18 ± 0.77 no./ cm) and 3.0 g·L-1 (1.90 ± 0.72 no./cm) concentrations. Bunch rot incidence, however, was highly dependent on disease pressure influenced by the precipitation during ripening. In year 2013 all treatments gave significantly lower infection incidence, while the extremity of rain in 2012 and 2014, resulted in no epidemic or high infection, respectively. The treatment with 2.0 g·L-1 BABA concentration decreased cluster parameters and led to the lowest disease incidence. Microscopic studies proved that successful treatments on cluster structure can be traced back to the female sterility caused by BABA. Our results presented clear evidence for the effectiveness of BABA treatment on Botrytis bunch rot by promoting looser clusters. [ABSTRACT FROM AUTHOR]

Fungicide resistance development in Botrytis cinerea threatens the efficacy of anilinopyrimidine (AP) fungicides, which have been used for botrytis bunch rot control in New Zealand vineyards for about 20 years. A 2016 survey of 33 vineyards in Gisborne, Hawke's Bay and Marlborough showed that the majority of 670 isolates tested in agar-based assays were sensitive to the AP cyprodinil (EC50 < 1 mg/litre), although 18% showed low-resistance (EC50 1-10 mg/litre) and 10% showed medium-resistance (EC50 >10 mg/litre). There was high cross-resistance to the APs cyprodinil and pyrimethanil. The survey also established baseline sensitivity to the succinate dehydrogenase inhibitor (SDHI) fungicide boscalid and >90% of isolates were sensitive (EC50 < 5 mg/litre). There was a low degree of cross-resistance between the SDHIs boscalid and fluopyram. There was also high sensitivity to fludioxonil (0.009 to 0.018 mg/litre) and to fenhexamid (0.49 to 0.76 mg/litre). [ABSTRACT FROM AUTHOR]

Botrytis cinerea and Neofusicoccum parvum are devastating fungal pathogens of grapevines. A total of 46 bacterial strains isolated from grapevines were screened for their antagonistic activity toward B. cinerea , which causes gray mold, and N. parvum , which causes cankers, trunk diseases and berry rot. In vivo screening using detached berries and leaf discs and in planta screening using growing grapevine cuttings were compared to select the most efficient biological control agents. On grapevine leaf discs, the most effective strain, Bacillus ginsengihumi , exhibited more than 80% antagonistic activity against the two major grapevine subpopulations of B. cinerea ( transposa and vacuma ). At the berry surface, the efficacy of the bacterial strains strongly depended on the presence or absence of wounds. On stem cuttings, some strains, notably Pantoea agglomerans , were able to significantly reduce the length of the necrosis caused by N. parvum . Thus, both the plant parts and the pathogen species may significantly affect the efficacy of the bacterial strain. Marked differences between the two fungal pathogen species in terms of strain inhibitory efficacy were observed on wounded berries, as some Bacillus spp. strains efficiently controlled B. cinerea but not N. parvum . Noticeable differences in bacterial antagonist efficiencies were detected between berries and leaf discs inoculated with B. cinerea ( transposa ), e.g., some Paenibacillus spp. strains were efficient on leaves but not on berries. Synergistic relationships were also revealed between several bacterial strains and the pathogens. Some bacterial strains (e.g., Bacillus licheniformis ) reduced B. cinerea rot severity in wounded and unwounded berries, but they increased N. parvum necrosis on stem cuttings. [ABSTRACT FROM AUTHOR]

Background and Aims Quantification of botrytis bunch rot ( BBR) in wine grapes, caused by B otrytis cinerea, is commonly done by visual estimation of the proportion of the area of individual bunches affected by BBR. Visual estimation was compared with four other quantification methods: digital image analysis, near-infrared and mid-infrared spectroscopy, and quantitative real-time polymerase chain reaction. Methods and Results Visual estimation was found to vary significantly ( P < 0.05) among assessors. Image analysis software ( Rot Bot) was developed to measure BBR severity from digital images of grape bunches. A published quantitative real-time polymerase chain reaction method was modified for use with mature grape berries. All quantification methods showed a significant relationship ( P < 0.05) with visual estimation. Conclusions Near-infrared and mid-infrared spectroscopy require further calibration to quantify accurately BBR of low severity. Quantitative real-time polymerase chain reaction was the most accurate method but is unsuitable for routine use in the vineyard. Rot Bot was the most suitable and practical alternative to visual estimation, requiring no specialised equipment. Significance of the Study Visual estimation was demonstrated to be prone to assessor bias. Rot Bot software is a suitable alternative that can be implemented immediately for objective quantification of BBR severity in white wine grapes. Rot Bot could be developed further and deployed in mobile devices for rapid sensing in the vineyard and easy collection of disease assessment data by wineries. [ABSTRACT FROM AUTHOR]

Botrytis bunch rot is the third economically most important disease in cool climates as most of the domesticated wine grape varieties are highly susceptible. In order to avoid or delay spreading of Botrytis infections until the grapes reach physiological ripeness, different management strategies as early defoliation or fungicide applications were developed. The major task within the scope of the German grapevine breeding program is the selection of fungus-resistant, climatic adapted vines with balanced, healthy yield and outstanding wine quality. Facing the long-term procedure of breeding, marker-assisted selection (MAS) is the most efficient method for an early selection of grapevine seedlings. MAS and marker development work effective for qualitative single locus traits as R-gene mediated downy and powdery mildew resistance. Corresponding resistance genes are not described for Botrytis for neither grapevines nor any other affected crop. However, new grapevine selections can be equipped with natural infection barriers protecting against Botrytis bunch rot represented by physical and mechanical characteristics: loose grape bunch architecture, and thick, impermeable berry cuticles. At the same time, such quantitative traits are difficult to trace for the development of molecular markers and require objective phenotyping. The present study aims at a new type of risk prediction for Botrytis bunch rot based on physical fruit traits (bunch architecture, berry impedance and berry texture) assessed with objective, highthroughput sensors. The preliminary predictive model is trained and tested on one-year data determined in 2021 including a mixture of 14 Botrytis-susceptible and -resilient varieties as well as elite breeding lines. Berry impedance and berry texture were identified as most effective traits enabling the forecast of Botrytis bunch rot infection with high accuracy. In addition, new QTLs were detected facilitating the development of molecular markers selecting for an increased resilience to Botrytis bunch rot. Furthermore, the physical barriers showed to be additional indicators for sunburn resilience and thus, are probably protecting berries against abiotic damages, too. [ABSTRACT FROM AUTHOR]

Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0·125 g L−1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L−1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC50) was 0·06 g L−1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia-lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7·4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15·5% in untreated controls and 5·9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13·8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11·5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action. [ABSTRACT FROM AUTHOR]

There is increasing interest in the use of biological control agents (BCAs) and plant resistance stimulants to suppress botrytis bunch rot in grapes, caused by Botrytis cinerea. Numerous different filamentous fungi, bacteria and yeasts have been selected as potential BCAs for control of grey mould based upon demonstrated antagonism towards B. cinerea. Biological suppression of the pathogen arises via competition for nutrients and space, the production of inhibitory metabolites and/or parasitism. Preformed and inducible grapevine defence mechanisms also contribute to disease suppression by preventing or delaying pathogenic infection. Furthermore, various biotic and abiotic agents can stimulate grapevine defence mechanisms and so elevate resistance to B. cinerea infection. Biosuppression of B. cinerea in vineyards, using BCAs and resistance stimulants, has been inconsistent when compared with that observed in controlled glasshouse or laboratory conditions. This may be attributable, in part, to the innate variability of the field environment. Research to improve field efficacy has focused on formulation improvement, the use of BCA mixtures and combinational approaches involving BCAs and plant resistance stimulants with complementary modes of action. [ABSTRACT FROM AUTHOR]

Effort to control gray mold caused by Botrytis cinerea failed in a table grapevine (Vitis vinifera) vineyard near Santiago, Chile where cyprodinil (Vangard 50 WP), a new fungicide of the anilinopyrimidine group, had been applied alone up to four times per year during two growing seasons. A relatively high frequency (38.5%) of resistant isolates of B. cinerea (EC50 for mycelial growth inhibition varied from 2.9 to 4.84 μg ml−1) may explain the partial loss of field control efficacy obtained. Resistance was correlated with a complete loss of in vivo sensitivity to cyprodinil. Resistant isolates of B. cinerea showed cross resistance to the anilinopyrimidines fungicides mepanipyrim and pyrimethanil. Cyprodinil partially impaired conidia germination and differentially affected conidial germination of resistant and sensitive isolates. Significant differences (p<0.05) in growth rate, sclerotia production and osmotic sensitivity were found among isolates of B. cinerea, but no correlation could be drawn between these biological differences and resistance or sensitivity. This indicates a disruptive selection characteristic of monogenic resistance. Thus, strategies were implemented to avoid the further development and spread of resistance in B. cinerea to the anilinopyrimidine fungicides. To our knowledge this constitutes the first mention of resistance in B. cinerea populations to anilinopyrimidine fungicides in South America. [Copyright &y& Elsevier]

Aureobasidium pullulans is a yeast-like fungus found on the surface of the grape berries that has been proven to act as a biocontrol agent for the management of grey mould disease caused by Botrytis cinerea. In this work, an indigenous strain of A. pullulans isolated from grape berries and selected according to the in vitro activity against B. cinerea, was used in vineyards of the winery where it originated, in comparison with a commercial product containing two A. pullulans strains with the aim of assessing its effectiveness as a biocontrol agent. The experimental design included daily meteorological data registration and the early defoliation of grapevines as treatments. The monitoring of A. pullulans strains on grape berries by plate counts and molecular methods as well as of B. cinerea symptoms on grape bunches was performed in the different trials from the end of flowering to the harvest time. Results highlighted that although no significant differences (p < 0.05) in the occurrence of B. cinerea were detected according to different treatments, the mean incidence of symptomatic berries ranged from 7 to 16%, with the lowest values recorded in bunches treated with the indigenous A. pullulans strain. The efficacy of the biocontrol agent was affected more by meteorological conditions than the defoliation practice. [ABSTRACT FROM AUTHOR]

A real-time loop-mediated isothermal amplification (LAMP) assay was evaluated for the detection of Botrytis cinerea in grapevine bunch trash, immature berries, and ripening berries. A simple method for the preparation of crude extracts of grape tissue was also developed for on-site LAMP analysis. When tested with 14 other fungal species frequently found in grapevines, the LAMP assay was specific and sensitive to a B. cinerea DNA quantity of 0.1 ng/µL. The sensitivity was further tested using bunch trash samples with B. cinerea colonization levels between 6 and 100% and with bulk-berry samples composed of 4 pathogen-free berries or 4 berries among which 25 to 100% had been inoculated with B. cinerea. The LAMP assay detected the lowest B. cinerea colonization level tested in bunch trash and in immature and mature berries in less than 20 min. In single-berry experiments, LAMP amplified B. cinerea DNA from all artificially inoculated individual immature and mature berries. No amplification occurred in B. cinerea-free material. The real-time LAMP assay has the potential to be used as a rapid on-site diagnostic tool for assessing B. cinerea colonization in bunch trash and B. cinerea latent infections in berries, which represent critical stages for decision-making about disease management. [ABSTRACT FROM AUTHOR]

• Enzymatic parameters of laccase of B. cinerea in presence of oenological tannins were determined. • Electrophoretic characterization of laccase of B. cinerea in presence of oenological tannin was investigated. • Bentonite, contrary to oenological tannins, did not reduce laccase activity. • Gallotannin, skin and seed tannins were the greatest to reduce laccase activity. • Oenological tannins seem to be great tool to prevent laccase effects and reduce use of SO 2. Enzymatic parameters (K M and V max), residual activity, effect of bentonite and electrophoresis characterization of laccase in the presence of different oenological tannins (OT) were investigated in relation to B. cinerea negative effects in grapes and musts. Five OT were tested (gallotannin, ellagitannin, quebracho, grape-skin and grape-seed) in comparison with ascorbic acid (AA), sulfur dioxide (SO 2) and bentonite. We added OT, AA, SO 2 and bentonite to botrytized must obtained by inoculation of grapes with B. cinerea strain 213. Laccase activity was measured by the syringaldazine method at different concentrations of substrate. Enzymatic parameters were determined using Michaelis-Menten and Lineweaver-Burk plots. The B. cinerea strain was also grown in a liquid medium for laccase production. Molecular weight of laccases and effect of OT upon these laccases were studied by SDS-PAGE. Results confirm that bentonite, contrary to OT, did not permit to reduce laccase activity. Regardless the tannin considered, V max , K M and laccase activity were reduced and gallotannin, grape-skin and grape-seed tannin presented the greatest ability. Efficiency of grape-seed tannin addition in order to reduce the laccase activity, was comparable to that of AA or SO 2 at the typical doses employed in oenology for each one. Oenological tannins appear to be excellent processing aids to prevent laccase effects and contribute to reduce the use of SO 2 in grapes and musts. [ABSTRACT FROM AUTHOR]

Although the use of biocontrol agents (BCAs) to manage plant pathogens has emerged as a sustainable means for disease control, global reliance on their use remains relatively insignificant and the factors influencing their efficacy remain unclear. In this work, we further developed an existing generic model for biocontrol of foliar diseases, and we parametrized the model for the Botrytis cinerea–grapevine pathosystem. The model was operated under three climate types to study the combined effects on BCA efficacy of four factors: (i) BCA mechanism of action, (ii) timing of BCA application with respect to timing of pathogen infection (preventative vs. curative), (iii) temperature and moisture requirements for BCA growth, and (iv) BCA survival capability. All four factors affected biocontrol efficacy, but factors iii and iv accounted for > 90% of the variation in model simulations. In other words, the most important factors affecting BCA efficacy were those related to environmental conditions. These findings indicate that the environmental responses of BCAs should be considered during their selection, BCA survival capability should be considered during both selection and formulation, and weather conditions and forecasts should be considered at the time of BCA application in the field. [ABSTRACT FROM AUTHOR]