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This review gives a perspective of selected advances made since the middle of the 20th century in plant disease modelling, and the associated increase in the number of models published during that time frame. This progress can be mainly attributed to advances in (i) sensors and automatic environmental data collection technology, (ii) instrumentation and methods for studying botanical epidemiology, and (iii) data analytics and computer science. We review the evolution of techniques for developing data-based (empirical) models and process-based (mechanistic) models using the wheat rusts as a case study. We also describe the increased importance of knowledge about biological processes for plant disease modeling by using apple scab as a second case study. For both wheat rusts and apple scab, we describe how the models have evolved over the last 50 years by considering certain milestones that have been achieved in disease modeling. Finally, we describe how plant disease models are used as part of a multi-modelling approach to develop decision-making tools in the application of Integrated Pest Management (IPM).

The Panelon Plant Health performed a pest categorisation of Cercosporaangolensis, the fungus responsible for Pseudocercospora fruit and leaf spot of citrus, for all territories except of the Union territories defined in Article 1 point 3 of Regulation (EU) 2016/2031. C.angolensis is listed in Annex IIAI of Directive 2000/29/EC and is not known to be present in the EU. The pathogen, which has recently been reclassified as Pseudocercosporaangolensis, is a well-defined, distinguishable fungal species affecting all cultivated Citrus spp. and Fortunellajaponica plants. It is currently distributed in sub-Saharan Africa (altitudes 80-1,800m) and Yemen. Although the epidemiology of P.angolensis is not well understood, infection is favoured by warm temperatures and humidity. The current distribution of the pathogen and climate matching suggests that it might not be well adapted to Mediterranean climates. However, the pathogen is also present in arid areas of Yemen and can infect young fruit with short wetness durations. Uncertainty exists on whether and at which extent the irrigation applied to EU citrus orchards can make the microclimate favourable for P.angolensis. There are no eco-climatic factors limiting the potential spread of the pathogen in the EU. Long-distance spread occurs by wind-disseminated conidia and movement of infected plants for planting and fruit. Short-distance spread occurs via water splash and/or wind-driven rain. In the infested areas, the disease causes premature abscission of young leaves and fruit resulting in yield losses up to 50-100%. Cultural practices and chemical measures applied in the infested areas reduce inoculum but they cannot eliminate the pathogen. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As P.angolensis is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non-quarantine pest is not met.

The Panelon Plant Health performed a pest categorisation of Venturianashicola, the causal agent of Asian pear scab, for the European Union (EU). The pathogen is a well-defined, distinguishable fungal species affecting Pyruspyrifolia var. culta, P.ussuriensis and P.bretschneideri in Asian countries. P.communis (European pear) is not a host of V.nashicola, but the host status of other Pyrus species is unclear. V.nashicola is not known to occur in the EU. It is listed in Annex IIAI of Directive 2000/29/EC. The pathogen could potentially enter the EU on host plants for planting and fruit originated in infested countries. There are no climatic factors limiting the potential establishment and spread of the pathogen in the EU, as its epidemiology is similar to those of Venturiainaequalis (apple scab) and Venturiapyrina (European pear scab), which are well-established in the EU. The hosts are present in the EU, but no data were found on their abundance and distribution. In the infested areas, V.nashicola causes premature leaf and fruit drop and fruit distortion resulting in considerable yield/quality losses. The introduction of the pathogen into the EU could cause yield/quality losses and environmental consequences because of the additional fungicide sprays for disease control. Cultural practices and chemical measures applied in the infested areas reduce the inoculum sources but they cannot eliminate the pathogen. Phytosanitary measures are available to mitigate the risk of introduction and spread of the pathogen in the EU. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As V.nashicola is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non-quarantine pest is not met. (C) 2017 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.

Botrytis bunch rot (BBR), caused by Botrytis cinerea, is one of the main diseases affecting grapevines. Due to the complexity of the B. cinerea life cycle and the existence of different infection pathways affecting grapevine tissues at both early and late growth stages, fungicides are usually applied sequentially at the end of flowering (A), prebunch closure (B), veraison (C), and before harvest (D). Interactions among fungicides (from different groups) applied at these growth stages were evaluated in this work, with focus on the strategies in which early- and late-season applications are combined (i.e., strategies AB, CD, ABC, ABD, ACD, BCD and ABCD). The evaluation was performed in a set of 116 studies carried out in different years and locations, by comparing the observed (b(obs)) and expected (b(pred)) efficacies in controlling BBR; b(obs) was calculated as the reduction of BBR severity in treated plots compared to untreated ones, while b(pred) was calculated by using a mathematical function. Early-season sprays (i.e., A and B) showed non-additive interactions (i.e., the observed efficacy was significantly lower than expected in case of additive effect) while late-season sprays (i.e., C and D) did. No significant synergistic effects were observed among fungicide sprays. In the early-season, spraying in A was more effective than in B, and both sprays (A and B) were useful under high disease pressure only, when the full ABCD strategy was needed for effective BBR control. Otherwise, the most effective combination was ACD, able to exploit the additive control of the early-season infection pathways and the multiple infection events during berry ripening.

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.

A field experiment was conducted between mid-August 2016 and mid-October 2017 in four table-grape vineyards in the Siriji Valley, Pernambuco State (Northeastern Brazil), to study the conidial dispersal dynamics of Botryosphaeriaceae fungi, causing grapevine trunk diseases (GTDs). Conidial dispersal was assessed by exposing microscope slides coated with Vaseline close to symptomatic plants and pruning debris. The slides were replaced every 2 weeks for a total of 30 sampling periods. Conidia of the genera Diplodia, Lasiodiplodia and Neofusicoccum were enumerated based on morphological characters. Conidia were collected from all four table-grape vineyards, confirming that these fungi are present as aerial inoculum and could be associated with GTDs in the region. Conidia of Diplodia and Lasiodiplodia were present in all the sampling periods, and those of Lasiodiplodia were the most abundant. Conidia of Neofusicoccum were found less frequently, and in less numbers than the other genera. Significant correlation between the number of conidia sampled and the amount of rain was observed for Diplodia only. Greater numbers of conidia were collected from pruning debris than from symptomatic plants. For Diplodia and Lasiodiplodia, the numbers of conidia gradually increased in September, increased sharply between March and June, and then decreased. These dynamics were described by a logistic equation, with hydro-thermal time (i.e., a combination of degree-days and relative humidity) as the independent variable (R-2 > 0.998).

The Panelon Plant Health performed a pest categorisation of the fungus Apiosporinamorbosa, the causal agent of black knot, for the EU. The identity of the pest is well established and reliable methods exist for its detection/identification. The pest is listed in Annex IIAI of Directive 2000/29/EC and is not known to occur in the EU. Apiosporinamorbosa is present in Alaska, Canada, Mexico and the continental states of the USA. The major hosts of A.morbosa are Prunusdomestica and Prunuscerasus; the host status of other Prunus species and hybrids is uncertain because of contradictory reports or lack of information. The pest could potentially enter the EU on host plants for planting and plant parts originating in infested third countries. Wood of Prunus spp. is also a pathway of entry, but of minor importance. The current pest distribution and climate matching suggest that the pest could establish and spread in the EU wherever the hosts are grown. In the infested areas, the pest causes girdling of twigs and occasionally of larger branches, whereas trees with multiple infections loose vigour, bloom poorly, and become unproductive, stunted and susceptible to winter injury and infection by other pathogens. The presence of black knots makes trees unsuitable for timber production. It is expected that the pest introduction and spread in the EU would impact host production. Uncertainty exists on whether the agricultural practices and chemical control methods applied in the EU could prevent the establishment and spread of A.morbosa. A.morbosa meets all the criteria assessed by EFSA for consideration as potential Union quarantine pest. As the pest is not known to occur in the EU, this criterion to consider it as Union regulated non-quarantine pest is not met. (C) 2018 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.

Futuras normativas europeas apostaran por el empelo de estrategias de control integado en el olivar que optimicen los tratamientos fungicidas, reduciendo el impacto ambiental y los costes economicos. En este sentido, el Grupo de Investigation Patologia Agroforestal de la Universitad de Cordoba esta trabajando en el desarrollo de una herramienta de toma de decision, creada a partir de modelos predictivos de enfermedades, que facilitara en gran medida el control del repilo dentro del macro de una agricoltura sostenibile.

Recently, a mechanistic model based on the life cycle of Botrytis cinerea was developed. This model considers weather conditions, vine growth stages and the main infection pathways. In this study, the model was validated in nine epidemics observed from 2015 to 2017, in three locations in Italy. At maturity, no botrytis bunch rot symptoms were observed in vineyards; however, shelf-life assays showed the presence of latent infections in mature berries, with max 13% disease severity. The infection severity assessed after shelf-life assays was used to classify the epidemics as: severe, intermediate and mild (observed severity). Epidemics were classified in these three group also based on the model output (predicted severity). The model correctly evaluated the 89% of the epidemics. The severity of epidemics was also compared to the control strategies adopted by grapevine growers; it was outlined that growers taken right decision in 33% of cases only. Therefore, the model could be used as a tool supporting decision-making for Botrytis bunch rot control; it predicts the infection risk during the main susceptible vine growth stages: i. flowering (BBCH 69); ii. pre- bunch closure (BBCH 77); iii. veraison (BBCH 83); iv. pre-harvest (BBCH < 89).

The Panel on Plant Health performed a pest categorisation of Venturia nashicola, the causal agent of Asian pear scab, for the European Union (EU). The pathogen is a well-defined, distinguishable fungal species affecting Pyrus pyrifolia var. culta, P. ussuriensis and P. bretschneideri in Asian countries. P. communis (European pear) is not a host of V. nashicola, but the host status of other Pyrus species is unclear. V. nashicola is not known to occur in the EU. It is listed in Annex IIAI of Directive 2000/29/EC. The pathogen could potentially enter the EU on host plants for planting and fruit originated in infested countries. There are no climatic factors limiting the potential establishment and spread of the pathogen in the EU, as its epidemiology is similar to those of Venturia inaequalis (apple scab) and Venturia pyrina (European pear scab), which are well-established in the EU. The hosts are present in the EU, but no data were found on their abundance and distribution. In the infested areas, V. nashicola causes premature leaf and fruit drop and fruit distortion resulting in considerable yield/quality losses. The introduction of the pathogen into the EU could cause yield/quality losses and environmental consequences because of the additional fungicide sprays for disease control. Cultural practices and chemical measures applied in the infested areas reduce the inoculum sources but they cannot eliminate the pathogen. Phytosanitary measures are available to mitigate the risk of introduction and spread of the pathogen in the EU. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As V. nashicola is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non-quarantine pest is not met.

The fungal genus Venturia Sacc. (anamorph Fusicladium Bonord.) includes plant pathogens that cause substantial economic damage to fruit crops worldwide. Although Venturia inaequalis is considered a model species in plant pathology, other Venturia spp. also cause scab on other fruit trees. Relative to the substantial research that has been conducted on V. inaequalis and apple scab, little research has been conducted on Venturia spp. affecting other fruit trees. In this review, the main characteristics of plant-pathogenic species of Venturia are discussed with special attention to V. inaequalis affecting apple, V. pyrina affecting European pear, V. nashicola affecting Asian pear, V. carpophila affecting peach and almond, Fusicladium oleagineum affecting olive, F. effusum affecting pecan, and F. eriobotryae affecting loquat. This review has two main objectives: (i) to identify the main gaps in our knowledge regarding the biology and epidemiology of Venturia spp. affecting fruit trees; and (ii) to identify similarities and differences among these Venturia spp. in order to improve disease management. A thorough review has been conducted of studies regarding the phylogenetic relationships, host ranges, biologies, and epidemiologies of Venturia spp. A multiple correspondence analysis (CA) has also been performed on the main epidemiological components of these Venturia spp. CA separated the Venturia spp. into two main groups, according to their epidemiological behavior: the first group included V. inaequalis, V. pyrina, V. nashicola, and V. carpophila, the second F. oleagineum and F. eriobotryae, with F. effusum having an intermediate position. This review shows that Venturia spp. affecting fruit trees are highly host-specific, and that important gaps in understanding the life cycle exist for some species, including V. pyrina; gaps include pseudothecia formation, ascospore and conidia germination, and mycelial growth. Considering the epidemiological information reviewed, th

Scab, caused by Fusicladium eriobotryae, is the main disease affecting loquat (Eriobotrya japonica) in the Mediterranean basin. A mechanistic epidemiological model developed in Spain to predict infection of loquat fruit by conidia was assessed in the main loquat cultivated area of Italy (Sicily). A 3-year study (2014-2016) was carried out in an experimental orchard on three loquat cultivars: Algerie, Peluche and San Filipparo. For each cultivar, output of the model was compared with observed scab development on fruits. The scab epidemics observed were different in different years and cultivars, representing a suitable data set for model validation. The model correctly predicted loquat scab, as demonstrated by the goodness of fit between model predictions and observed disease incidence on fruits (R2> 0.85), confirming the accuracy and robustness of the model for predicting scab development in loquat orchards. The use of the model for fungicide scheduling against F. eriobotryae may improve the management of loquat scab by reducing the number of required fungicide applications.

Black rot, caused by the fungus Guignardia bidwellii, is a polycyclic disease affecting grape leaves and berries. In environmentally controlled experiments and in a 3-year field study, the effects of temperature and relative humidity (RH) were assessed on the following growth parameters of G. bidwellii: (i) formation of pycnidia and cirri in grape leaf lesions, (ii) production and germination of conidia, and (iii) length of the period between lesion appearance and pycnidia production. Pycnidia were produced between 5 and 35°C and at 90 to 100% RH but more pycnidia were produced between 20 and 30°C. No pycnidia were produced at RH < 90%. The first pycnidia were produced in approximately 2 days after lesion appearance at ≥20°C and in 8 days at 5°C; pycnidia continued to be produced on the same lesion for 5 to 16 days after lesion appearance, depending on the temperature. Models were developed to describe the effect of temperature and RH on pycnidia production, accounting for 95 and 97% of variability, respectively. Cirri were extruded only between 15 and 35°C and mainly at 100% RH. Field experiments confirmed that pycnidia are produced for several days on a leaf lesion and that the length of the period between lesion appearance and pycnidia production depends on temperature. Overall, the findings showed that production of conidia requires high humidity; under field conditions, some hours at high humidity, which usually occur at nighttime, rather than constant high humidity may be sufficient.

The ascomycete Guignardia bidwellii is an economically important pathogen in many grapevine-growing areas. Primary infections are caused by ascospores and conidia produced in mummified berries and in cane lesions. Secondary infections are caused by the conidia produced by pycnidia formed in leaf lesions and, in later season, in rotted berries. Environment-controlled experiments were conducted to study the production dynamics of G. bidwellii conidia on grape leaf lesions as influenced by: i) repeated washing events, and ii) alternate dry and wet periods. Under optimal environmental conditions (25 °C, 100 % relative humidity), production of conidia declined over washings and was almost completely depleted after four washings. When pycnidia were kept in a low humidity environment (average of 54 % relative humidity) between two successive washings, the production of conidia progressively diminished as the time between washings increased, with few conidia being still produced after 87 days. This decline in conidial production was faster at 29 °C than at 20 °C. This information is relevant in that it determines the potential of black-rot lesions to produce conidia along the grape-growing season and, therefore, their contribution to epidemic development.

Downy mildew (DM) caused by the oomycete Plasmopara viticola is one of the most important grapevine diseases. The use of DM resistant grapevine varieties is getting increasingly consideration and importance in Europe, as a possible mitigation measure to reduce the use of fungicides. The goal of the present work is to characterize the resistance components to DM in grapevine genotypes (specifically Regent, Rkatsiteli, Bronner, Johanniter, Solaris, 32-078, 34-111, Villaris, Calandro, Felicia, Reberger, Palava, Royal Merlot, Gf.93-22-6, Early Merlot) bringing different resistance genes (Rpv 3, 4, 10, 11 and 12) from Muscadinia and Vitis American species. The following resistance components were assessed in monocyclic experiments carried out under environment controlled conditions: (i) infection efficiency of sporangia (as a percentage of the inoculation sites showing DM symptoms); (ii) AUDPC (area under the disease progress curve); (iii) incubation length, (iv) latency period, (v) sporangia produced per unit of infected area (as number of sporangia per mm2 of lesion area); and (v) infectiousness of the produced sporangia. Resistance components were assessed after artificial inoculation of leaf discs with a natural population of P. viticola. Leaf discs were excised from fully developed, young leaves collected in 2014 and 2015 at shoot growing and at flowering/fruit set. Resistance components were expressed at different degrees in the different genotypes and at the different sampling times, with significant differences in comparison to the susceptible Vitis vinifera variety used as reference (Merlot). For instance, infection efficiency ranged between 60 and 99%, the latency period lasted between 104 and 132 degree-days, and the production of sporangia varied between 80 and 1.1×103 sporangia per mm2 of DM lesion. The research was partially funded by the European collaborative project “Innovine”, that has received funding from the European Union’s Seventh Framework Program