Exploit biodiversity in viticultural systems to reduce pest damage and pesticide use, and increase ecosystems services provision: the BIOVINE Project

Organic vineyards still rely on large external inputs to control harmful organisms (i.e., pests). The BIOVINE project aims to develop natural solutions based on plant diversity to control pests and reduce pesticide dependence. The capability of plants of increasing the ecosystem resistance to pests and invasive species is a well-known ecosystem service. However, monocultures (including vineyards) do not exploit the potential of plant diversity. BIOVINE aims to develop new viticultural systems based on increased plant diversity within (e.g., cover crops) and/or around (e.g., hedges, vegetation spots, edgings) vineyards by planting selected plant species for the control of arthropods, soil-borne pests (oomycetes, fungi, nematodes), and foliar pathogens. Candidate plants will be identified by a literature review, and the selected ones will be tested in controlled environment or small-scale experiments. The ability of the selected plants to: i) attract or repel target arthropod pests; ii) conserve/promote beneficials; iii) control soil-borne pests by means of biofumigation; iv) carry mycorrhizal fungi to the vine root system to increase plant health (growth and resistance); and v) control foliar pathogens by reducing the inoculum spread from soil, will be investigated. New viticultural systems able to exploit plant diversity will then be designed based on results of BIOVINE activities, following a design-assessment-adjustment cycle, which will then be tested by in-vineyard experiments in France, Italy, Romania, Slovenia, Spain and Switzerland for a 2-year period. Innovative viticultural systems should represent an improved way for pest control in organic viticulture, meanwhile they should positively affect functional biodiversity and ecosystem services. New control strategies may provide financial opportunities to vine growers and lower their reliance on pesticides

ASCOPORE PRODUCTION, DISPERSAL AND SURVIVAL IN FUSARIUM GRAMINEARUM

Fusarium graminearum causa la fusariosi della spiga nei cereali a paglia. Il fungo produce sia conidi che ascospore sui residui della coltura precedente, le ascospore sono prodotte in periteci. La produzione e maturazione di periteci e ascospore in risposta a diverse condizioni di temperatura e umidità relativa sono state studiate. Dato che le condizioni atmosferiche influenzano anche l’umidità del substrato su cui l’inoculo è prodotto, la relazione tra i fattori atmosferici e l’umidità dei residui colturali di mais è stata esaminata. I fattori atmosferici influenzano anche il rilascio delle ascospore. L’effetto della temperatura è stato studiato in vitro. Mediante esperimenti in condizioni naturali, sono state definite regole per l’individuazione di condizioni favorevoli al rilascio di ascospore sulla base di pioggia e deficit di pressione di vapore. La distribuzione delle ascospore e dei conidi all’interno della vegetazione del frumento è quindi stata studiata mediante l’uso di captaspore passivi. Le ascospore possono essere rilasciate e depositarsi sulle spighe in condizioni non favorevoli per la germinazione. La germinazione di ascospore sottoposte a periodi asciutti di diversa durata, e a diverse condizioni di temperatura e umidità relativa durante il periodo asciutto, è stata studiata sia in vitro che in planta.Fusarium graminearum causes Fusarium head blight of small-grain cereals. The fungus produces conidia and ascospores on the previous crop residues, ascospores are formed in perithecia. Production and maturation of perithecia and ascospores at several temperature and relative humidity conditions were studied. As environmental conditions also influence the moisture content of the substrate on which inoculum is produced, the relationship between environmental factors and moisture of maize residues was assessed. Environmental factors also influence ascospore discharge. The effect of temperature was studied in vitro. Experiments in natural condition allowed to define rules for conditions leading to ascospore discharge, based on rain and vapor pressure deficit. Once discharged, the distribution of ascospores and conidia in the wheat canopy was studied using passive spore traps. Ascospores can be discharged and deposit on wheat spikes also in conditions that are unfavorable for germination. Germination of ascospores incubated in dryness for periods of several length, in several condition of temperature and relative humidity during dryness, was studied both in vitro and in planta

Numbers of <i>Fusarium graminearum</i> ascospores sampled daily.

<p>Ascospores were sampled from the air above maize stalk residues bearing mature perithecia at the University of Piacenza (North Italy) in 2012 (A), 2013 (B), and 2014 (C). * indicates days in which no ascospores were erroneously predicted according to the discharge criteria R ≥ 2 mm/day or VPD ≤ 11 hPa.</p

Weather data during sampling and number of ascospores sampled in specific periods.

<p>Hourly air temperature (T), relative humidity (RH), rain, wetness duration (WD), vapor pressure deficit (VPD), and numbers of <i>Fusarium graminearum</i> ascospores sampled from the air above maize stalk residues bearing mature perithecia at the University of Piacenza (North Italy) in 2013. Panels show three different period of 48 hours: from 12.00 of 10 May to 11.00 of 12 May (A), from 12.00 of 15 May to 11.00 of 16 May (B) and from 00.00 of 9 June to 23.00 of 10 June (C).</p

Parameters and statistics of the regression models describing the relationships between weather data and daily numbers of airborne <i>Fusarium graminearum</i> ascospores sampled in North Italy in 2012 to 2014.

<p>¹ In the first data set, all sampling days were considered, whether or not ascospores were discharged from perithecia (n = 154); in the second data set, only days with ascospore peaks, i.e., ≥ 30 ascospores / m³ air per day, were considered (n = 27).</p><p>² Tav, Tmin, Tmax = average, min, and max daily temperature; WDt = total wetness duration; VPD = vapor pressure deficit; Asc(0,1) = dycotomic variables with 0 and 1 being no or yes ascospores, respectively.</p><p>³ Parameters of the following regression model: Y = β₀ + β₁X₁ + … + β_nX_n; Y = natural logarithm of ascospore numbers. Ascospores were sampled with a volumetric spore sampler from the air above maize stalk residues bearing mature <i>F</i>. <i>graminearum</i> perithecia; ascospore numbers were transformed by using the function ln(x+1) for the analysis.</p><p>⁴ Standard error of the parameters.</p><p>⁵ Standard error of the estimates.</p><p>Parameters and statistics of the regression models describing the relationships between weather data and daily numbers of airborne <i>Fusarium graminearum</i> ascospores sampled in North Italy in 2012 to 2014.</p

Model prediction in the sampling periods.

<p>Numbers of <i>Fusarium graminearum</i> ascospores predicted daily by model (1) (dotted line) and model (2) (points) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138860#pone.0138860.t005" target="_blank">Table 5</a>) and observed (line) at the University of Piacenza (North Italy) in 2012 (A), 2013 (B), and 2014 (C). Ascospores were sampled with a volumetric spore sampler from the air above maize stalk residues bearing mature perithecia; ascospore numbers are expressed as ln(x+1).</p

Characteristics of the ROC curves obtained using weather data as predictors of discharge and peaks of <i>Fusarium graminearum</i> ascospores in North Italy in 2012 to 2014.

<p>¹ Tav, Tmin, Tmax = average, min, and max daily temperature; RHav, RHmin, RHmax = average, min, and max daily relative humidity; WDt = total wetness duration; RH90 = hours with RH > 90%; VPD = vapor pressure deficit; Rt = total rain.</p><p>² Ascospores were sampled with a volumetric spore sampler from the air above maize stalk residues bearing mature <i>F</i>. <i>graminearum</i> perithecia.</p><p>³ Peaks are defined as days with ≥ 30 ascospores / m³ air.</p><p>⁴ Area under the ROC curve.</p><p>Characteristics of the ROC curves obtained using weather data as predictors of discharge and peaks of <i>Fusarium graminearum</i> ascospores in North Italy in 2012 to 2014.</p

Model prediction.

<p>Numbers of <i>Fusarium graminearum</i> ascospores predicted by model (1) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138860#pone.0138860.t005" target="_blank">Table 5</a>) based on average air temperature (Tav), maximum air temperature (Tmax), and vapor pressure deficit (VPD). Average relative humidity (RHav) is shown as a component for calculating VPD. Predicted ascospore numbers are expressed as ln(x+1).</p

Correlation coefficients between daily numbers of airborne <i>Fusarium graminearum</i> ascospores and weather data registered during the day of ascospore trapping (Day i) and the day before trapping (Day i-1) in North Italy in 2012 to 2014.

<p>¹ Tav, Tmin, Tmax = average, min, and max daily temperature; RHav, RHmin, RHmax = average, min, and max daily relative humidity; WDt = total wetness duration; RH90 = hours with RH > 90%; VPD = vapor pressure deficit; Rt = total rain.</p><p>² Pearson correlation coefficient (n = 154); ascospores were sampled with a volumetric spore sampler from the air above maize stalk residues bearing mature <i>F</i>. <i>graminearum</i> perithecia; ascospore numbers were transformed by the function ln(x+1) for the analysis.</p><p>Correlation coefficients between daily numbers of airborne <i>Fusarium graminearum</i> ascospores and weather data registered during the day of ascospore trapping (Day i) and the day before trapping (Day i-1) in North Italy in 2012 to 2014.</p

ROC curve.

<p>Sensitivity vs. 1-Specificity (ROC curve) in predicting discharge (line) and peaks (dotted line) of <i>Fusarium graminearum</i> ascospores as affected by different cut-off points for the number of hours per day with vapor pressure deficit (hPa) ≤ the cut-off point at the University of Piacenza (North Italy) in 2012 to 2014. Points and numbers inside the plot are the best cut-off points.</p