Sporulation rate in culture and mycoparasitic activity, but not mycohost specificity, are the key factors for selecting Ampelomyces strains for biocontrol of grapevine powdery mildew (Erysiphe necator)

To develop a new biofungicide product against grapevine powdery mildew, caused by Erysiphe necator, cultural characteristics and mycoparasitic activities of pre-selected strains of Ampelomyces spp. were compared in laboratory tests to the commercial strain AQ10. Then, a 2-year experiment was performed in five vineyards with a selected strain, RS1-a, and the AQ10 strain. This consisted of autumn sprays in vineyards as the goal was to reduce the number of chasmothecia of E. necator, and, thus, the amount of overwintering inocula, instead of targeting the conidial stage of the pathogen during spring and summer. This is a yet little explored strategy to manage E. necator in vineyards. Laboratory tests compared the growth and sporulation of colonies of a total of 33 strains in culture; among these, eight strains with superior characteristics were compared to the commercial product AQ10 Biofungicide® in terms of their intrahyphal spread, pycnidial production, and reduction of both asexual and sexual reproduction in E. necator colonies. Mycoparasitic activities of the eight strains isolated from six different powdery mildew species, including E. necator, did not depend on their mycohost species of origin. Strain RS1-a, isolated from rose powdery mildew, showed, togetherwith three strains from E. necator, the highest rate of parasitism of E. necator chasmothecia. In field experiments, each strain, AQ10 and RS1-a, applied twice in autumn, significantly delayed and reduced early-season development of grapevine powdery mildew in the next year. Therefore, instead of mycohost specificity of Ampelomyces presumed in some works, but not confirmed by this study, the high sporulation rate in culture and the mycoparasitic patterns became the key factors for proposing strain RS1-a for further development as a biocontrol agent of E. necator

Biology, epidemiology and control of the sexual stage of Erysiphe necator (Schwein.), the grapevine powdery mildew fungus

Erysiphe necator (Schwein.) è l’agente causale dell’oidio della vite. Esso è in grado di svernare come ascospore all’interno di corpi fruttiferi, i chasmoteci, oppure come micelio in gemme infette. Le ascospore sono rilasciate nella primavera successiva e causano infezioni primarie che danno origine all’epidemia. Di conseguenza la riduzione dell’inoculo primario svernante potenzialmente riduce le epidemie nella stagione successiva. I primi sei capitoli di questa tesi riguardano nuove conoscenze sulla biologia, epidemiologia e modellistica del patogeno. Due nuovi modelli meccanicistici che simulano, rispettivamente, la maturazione e dispersione dei chasmoteci e le infezioni ascosporiche sono stati sviluppati ed è stata studiata approfonditamente la dinamica di maturazione e dispersione delle ascospore stesse. Nei restanti quattro capitoli il controllo del patogeno è stato riconsiderato in accordo con le linee guida della gestione integrata del vigneto. In particolare è stata valutata l’efficacia di diversi fungicidi, dell’iperparassita Ampelomyces spp. e di un olio minerale nel ridurre il numero di chasmoteci prodotti in autunno, nel distruggere gli stessi durante l’inverno e nel controllare le infezione primarie ascosporiche in primavera.Erysiphe necator (Schwein.) is the causal agent of grapevine powdery mildew. It survives the winter in two ways: as ascospores in overwintering fruiting bodies, the chasmothecia, and as mycelium in infected buds. Ascospores that are repeatedly released and cause primary infections in the following grapevine growing season and trigger powdery mildew epidemics. Consequently, the reduction of the overwintering inoculum may reduce powdery mildew epidemics in the next season. In order to verify this statement and develop sanitation as a relevant strategy to be used in integrated management of grape powdery mildew, different studies were performed during this Doctorate. The first six chapters of this dissertation pertain to new findings about the biology, epidemiology and modeling of the pathogen. A new mechanistic model predicting maturation and dispersal of chasmothecia was developed, dynamics of ascospore maturation and dispersal were studied and another mechanistic model simulating ascosporic infections was developed. In the last four chapters the control of the pathogen was redrawn according to the Integrated Pest Management concept: the efficacy of fungicides, the hyperparasite Ampelomyces spp., and mineral oil in reducing chasmothecia production in fall, in killing chasmothecia before bud break, and in controlling ascosporic infections in spring was investigated

VineMan.org: Europe supports the research on organic viticulture

The Kick-off meeting of the research project VineMan.org, coordinated by Prof. Vittorio Rossi within the CORE Organic II, a transnational research cooperation project supported by the European Commission, was held at the Università Cattolica del Sacro Cuore of Piacenza on the 24th January 2012. The meeting was attended by the representatives of each research unit coming from Italy, Austria, Germany, Spain and Slovenia. Also representatives of the Italian Ministry for Agriculture (Ministero delle Politiche Agricole, Alimentari e Forestali) attended the meeting. The project, as explained by Prof. Rossi in the initial presentation, aims at designing, developing, and testing innovative cropping systems for organic vineyards in Europe. Organic agriculture is defined as a production management system which promotes and enhances the agro-ecosystem in the whole, including biodiversity, biological cycles, and soil biological activity. In organic viticulture, plant protection is based on: conservation of the fertility and health of the soil; choice of appropriate viticulture practices, resistant varieties and training systems; timing of the protection measures and application methods; enhancement of natural defense mechanisms; biological pest control and habitat management. Plant resistance, plant management, rational application of protection measure and use of biological control agents (BCAs) are the pillars of disease control in organic viticulture which are addressed by the VineMan.org project. Considering that organic vineyards cover more than 165.000 hectares in Europe, the results of the project should have a large impact on the European territory. Insufficient disease control (which will be worsen by the progressive reduction of copper fungicides defined by the European Commission) is often the main reason for growers to not adapt, or even abandon, organic production. Development of new and efficient strategies for controlling grape diseases will provide to the EU grape growers new opportunities for entering/remaining in this sector, whose market is constantly growing. Different dissemination activities are foreseen by the project, such as, the production of a leaflet, a web-site dedicated to the project, seminars and workshops in experimental vineyards for stakeholders and end users and, last but not least, a final conference of international scientific relevance

New records of microcyclic conidiogenesis in some powdery mildew fungi

Microcyclic conidiogenesis (MC) was recently described in several species of powdery mildew fungi. This process, defined as the production of conidia on a fungal spore without any, or only a minimal, involvement of hyphal growth, was observed on powdery mildew conidia that have already germinated on host plant surfaces and have been attached to the epidermal cells. Most probably, MC contributes to a quick propagation of young powdery mildew colonies because new conidia are sometimes produced in a shorter time on microcyclic conidiophores than on the hyphae of the young mycelium. This article reports MC in Erysiphe necator ex grapevine, Podosphaera leucotricha ex apple, Golovinomyces orontii ex tobacco, and Neoerysiphe galeopsidis ex Lamium purpureum based on light and low-temperature scanning electron microscopic studies

La difesa del vigneto biologico: l’unione fa la forza!

L’agricoltura biologica, e in particolare la viticoltura biologica, sono cresciute considerevolmente nell’ultimo decennio ed hanno ancora ampi margini di miglioramento. Il progetto di ricerca VineMan.org (www.vineman-org.eu), finanziato nell’ambito del network europeo di cooperazione transnazionale CORE Organic II, ha l’obiettivo di migliorare il controllo delle malattie, uno dei principali e più difficili compiti del viticultore biologico, integrando la resistenza delle piante, pratiche agricole di gestione del vigneto, i sistemi di supporto alle decisioni e l’utilizzo di agenti di biocontrollo

ACTIVITY OF DIFFERENT PLANT PROTECTION PRODUCTS AGAINST CHASMOTHECIA OF GRAPEVINE POWDERY MILDEW

Erysiphe necator, the casual agent of grapevine powdery mildew, is one of the most harmful pathogens in viticulture; its control accounts for most of the fungicides applied to grapes. At the end of summer, powdery mildew colonies on grapevine leaves form chasmothecia (fruiting bodies) that survive the winter. In the following spring, the chasmothecia discharge ascospores that cause primary infections, which can then trigger epidemics. To determine whether treatments against chasmothecia reduce the primary inoculum and improve disease control in the next season, the efficacies of eight fungicides, one biofungicide, and one insecticide (with collateral activity against powdery mildew) were compared in three strategies with applications in: (i) summer/fall against developing chasmothecia (in a greenhouse and in a vineyard); (ii) winter against mature chasmothecia; and (iii) spring to control ascosporic infections. Applications to developing chasmothecia in the greenhouse reduced the maturation of fruiting bodies by 64% (spiroxamine) to 41% (A. quisqualis) compared to the untreated control, and reduced ascospore viability by 75%. Applications to developing chasmothecia in the vineyard prevented ascocarp formation in the fall and reduced disease intensity by 50% at early berry development, particularly if primary inoculum was abundant. Winter applications were less effective while spring applications reduced disease by >90% or by 80% (sulphur). In conclusion, late-season fungicide application directed toward the developing primary inoculum reduced the need for intensive fungicide application in the following spring in high-risk vineyards. Nonetheless, early season, preventative powdery mildew control is recommended in vineyards where early, severe disease outbreak is expected