Development and Validation of a Mechanistic Model That Predicts Infection by Diaporthe ampelina, the Causal Agent of Phomopsis Cane and Leaf Spot of Grapevines.

Phomopsis cane and leaf spot (PCLS), known in Europe as "excoriose," is an important fungal disease of grapevines caused by Diaporthe spp., and most often by Diaporthe ampelina (synonym Phomopsis viticola). PCLS is re-emerging worldwide, likely due to climate change, changes in the management of downy mildew from calendar- to risk-based criteria that eliminate early-season (unnecessary) sprays, and the progressive reduction in the application of broad-spectrum fungicides. In this study, a mechanistic model for D. ampelina infection was developed based on published information. The model accounts for the following processes: (i) overwintering and maturation of pycnidia on affected canes; (ii) dispersal of alpha conidia to shoots and leaves; (iii) infection; and (iv) onset of disease symptoms. The model uses weather and host phenology to predict infection periods and disease progress during the season. Model output was validated against 11 independent PCLS epidemics that occurred in Italy (4 vineyards in 2019 and 2020) and Montenegro (3 vineyards in 2020). The model accurately predicted PCLS disease progress, with a concordance correlation coefficient (CCC) = 0.925 between observed and predicted data. A ROC analysis (AUROC>0.7) confirmed the ability of the model to predict the infection periods leading to an increase in PCLS severity in the field, indicating that growers could use the model to perform risk-based fungicide applications.

Dynamics of Diaporthe ampelina Conidia Released from Grape Canes that Overwintered in the Vineyard.

Phomopsis cane and leaf spot (PCLS) is an important disease of grapevines that is mainly caused by Diaporthe ampelina. Dispersal dynamics of D. ampelina spores were investigated in two vineyards, one in northern Italy and one in Montenegro, by using spore samplers that collected α- and ß-conidia from rain water running off from PCLS-affected canes. The canes were collected from each vineyard, deployed, and overwintered in the corresponding vineyards. In each of three years (2016, 2017, and 2018), conidial dispersal was investigated during one (Montenegro) or two (Italy) growing seasons following the deployment of the PCLS-affected canes. In the first growing season following cane deployment in both vineyards, α-conidia were mostly found in runoff water after grapevine bud break, especially in April and May, and ß-conidia were regularly found in numbers comparable to those of α-conidia, most frequently from June to September. In Italy, high numbers of α- and ß-conidia were also collected during the second growing season following cane deployment. The dispersal dynamics of α-conidia over time were described by a Gompertz equation using hydrothermal time (i.e., the accumulated effect of temperature on the maturation rate of pycnidia on days in which the number of hours of wetness was ≥6 or 9 h), with R2 and concordance correlation coefficient >0.9. Rain (≥0.2 mm) was a good predictor of conidial dispersal, with an overall accuracy of 0.97. These results increase our understanding of D. ampelina spore dispersal and should be integrated into warning systems for PCLS management.

Natural Fungicolous Regulators of Biscogniauxia destructiva sp. nov. That Causes Beech Bark Tarcrust in Southern European (Fagus sylvatica) Forests.

Mycoparasites are a collection of fungicolous eukaryotic organisms that occur on and are antagonistic to a wide range of plant pathogenic fungi. To date, this fungal group has largely been neglected by biodiversity studies. However, this fungal group is of interest, as it may contain potential biocontrol agents of pathogenic fungi that cause beech Tarcrust disease (BTC), which has contributed to the devastation of European beech (Fagus sylvatica) forests. Biscogniauxia nummularia has been demonstrated to cause BTC. However, a trophic association between mycoparasites and pathogenic Biscogniauxia spp., has not been established. This study aimed to taxonomically identify and characterize Biscogniauxia, a fungus causing destructive BTC disease in European beech at Lovcen national park, Montenegro and to uncover the diversity of mycopathogens that are natural regulators of xylariaceous Biscogniauxia stroma formation, associated with beech decline. This finding is supported by distinctive phylogenetic and evolutionary characteristics, as well as unique morphological-microscopic fungal features indicating that Biscogniauxia from Montenegro, which is a major cause of BTC occurring in ancient beech forests at the edge of southern Fagus sylvatica distribution, may be described as a novel fungus specific to Fagus. Its evolutionary nuSSU-complete ITS-partial nuLSU rDNA phylogeny indicates its likely emergence by asexual fusion or introgressive hybridization between diverged B. nummularia and B. anceps species. The name Biscogniauxia destructiva is proposed for the novel fungus, as it is aggressive and highly destructive BTC disease.

Growth supression of plant pathogenic fungi using bryophite extracts / Supressão de crescimento de fungos patogênicos de plantas usando extratos de briófitas

Chemicals are often used in attempts to control diseases caused by plant pathogenic fungi during food production. However, chemicals can have adverse effects not just on food, but they also remain active for a long time within ecosystems, and thus are not environmentally friendly. Therefore,development of bio-treatment and avoiding use of chemicals are urgently needed. With the aim of studying and developing new environmentally-friendly treatments, we tested extracts from selected bryophyte species(Porella platyphylla, Cinclidotus fontinaloides and Anomodon viticulosus) on five plant pathogenic fungi under controlled conditions. The fungi (Botryosphaeria dothidea, Phomopsis viticola, Calosphaeria sp., Colletotrichum acutatum and Monilinia laxa) were selected based on common diseases they cause on fruits and grapevine. They were isolated in cultures and treated with bryophyte extracts. Bryophyte extracts were shown to be effective in suppression of certain plant pathogenic fungi growth and to have a huge potential in development of novel biotechnological treatments and biofungicides. The best results were achieved in inhibition of B. dothidea, P. viticola and Calosphaeria sp.

Fungos fitopatogênicos são controlados com produtos químicos para combater doenças causadas por eles durante a produção de alimentos. Tais produtos são ruins não apenas para a alimentação, mas também podem permanecer por muito tempo nos ecossistemas, portanto, não são ecologicamente corretos. Desta forma, os biotratamentos e a prevenção de usos químicos são urgentemente necessários no futuro próximo. Com o objetivo de estudar e desenvolver nova alternative decontrole de doenças de plantas, testamos os extratos de espécies de briófitas selecionadas (Porella platyphylla, Cinclidotus fontinaloides e Anomodon viticulosus) em cinco fungos fitopatogênicos (Botryosphaeria dothidea, Phomopsis viticola, Calosphaeria sp., Colletotrichum acutatum e Monilinia laxa) em condição controlada. Estes fungos, selecionados com base nas doenças que causam em frutos e videiras, foram isolados em culturas puras e tratados com os respectivos extratos de briófitas. Os extratos de briófitas demonstraram ser eficazes na supressão de certos fungos fitopatogênicos e têm um enorme potencial no desenvolvimento de novos biofungicidas e tratamentos biotecnológicos. Os mais interessantes resultados foram obtidos na inibição de B. dothidea, P. viticola eCalosphaeria sp.

Viruses Associated with Fig Mosaic Disease in Different Fig Varieties in Montenegro.

Symptoms of fig mosaic disease have been noticed on leaves of fig (Ficus carica) for several decades, in Montenegro. In 2014, leaf samples were collected from trees of six fig cultivars in a plantation located in the main fig-producing area of Montenegro, to study the disease. After RNA isolation, samples were tested by RT-PCR for detection of nine fig viruses and three viroids. Four viruses were detected: fig leaf mottle-associated virus 1 (FLMaV-1), fig mosaic virus (FMV), fig mild mottle-associated-virus (FMMaV) and fig badnavirus 1 (FBV-1). Most of the viruses were present in mixed infections. The amplicons of the viruses were directly sequenced from both directions. A BLAST search of these sequences revealed sequence identities with their closest counterparts at GenBank of 92, 97, 92 and 100%, for FLMaV-1, FMV, FMMaV and FBV-1, respectively. Different responses in symptom expression due to the various virus combinations detected have been demonstrated. Variety Susilica had the least symptom expression, with only one virus (FBV-1) found. Considering that the production of figs in Montenegro is increasing and has a substantial relevance in this geographic location, the results indicate that more attention should be given to improving the phytosanitary condition of fig trees in the country.