Environmental variables influencing the incidence of Pierce's disease

Abstract

Background and Aims Pierce's disease (PD) of cultivated grape, Vitis vinifera, caused by the bacterium Xylella fastidiosa (Xf) and transmitted by xylem‐feeding insects, can lead to vine decline and death. Infection and expression of PD among or within vineyards vary, depending on known environmental variables, such as climate and Xf vegetative reservoirs, as well as some which are little studied with respect to PD, such as soil, water and nutrition. Methods and Results We collected data on over 30 environmental variables and used canonical correspondence analysis (CCA) and discriminant analysis (DA) to analyse their relationship to PD infection, sharpshooter density and Xf reservoir plants. The CCA found high positive correlation between PD and vineyard proximity to citrus orchards, and moderately positive correlation between PD and grape petiole Zn concentration and soil pH. The DA retained eight variables and predicted an increased risk of PD with higher cover of annual grasses, proximity to riparian habitat, increasing soil pH and increasing petiole Zn; PD risk decreased with higher perennial grass cover, higher latitude, increasing vine water stress and increasing soil cation exchange capacity. Conclusions We identified several novel variables which contributed to expression of PD and may improve the understanding of the role of environment in the disease triangle. Significance of the Study That the models include factors relating to soil and soil/plant relations suggest that these variables and their interactions play a role in constitutive or induced plant defenses to Xf and provides a basis for further study into management options for PD.

Update of the Scientific Opinion on the risks to plant health posed by Xylella fastidiosa in the EU territory

“…In relation to productive lifespan this corresponds to around 10% loss. For very susceptible varieties (Barbera, Chardonnay, Pinot) if conditions are favourable to the disease, they can be systemically infected already during the first year. Costello et al. () evaluated incidence in Sonoma County (California): from 0.02% to 37.1%. Sonoma County has very hot summer.…”

“…Chardonnay Samples that tested positive for X. fastidiosa : 56 positive out of 120 using ELISA 65 positive out of 120 using PCR Samples were taken from symptomatic (leaf scorch) and asymptomatic plants Comparison of X. fastidiosa detection in whole tissue samples with xylem fluid samples Both whole‐tissue and xylem fluid samples were collected from 30 grapevines from a commercial vineyard in Temecula, CA and from the University of California, Riverside campus Bextine and Miller () Vitis vinifera Cultivars: Site 1 – Merlot Site 2 – Merlot Site 3 – Cabernet Sauvignon Site 4 – Merlot Site 5 – Sauvignon Blanc Site 6 – Grenache Site 7 – Zinfandel Site 8 – Zinfandel Incidence in all 8 sites: Tabella 3 Site 1 – 23.7% of 500 Site 2 – 0.02% of 500 Site 3 – 0.02 of 500 Site 4 – 37.1% of ,1179 Site 5 – 26.2 of 1,448 Site 6 – 5.5 of 6,056 Site 7 – 25.8% of 4,021 Site 8 – 0.2% of 3,192 Collection in vineyard field sites located in the Knight's Valley (Sonoma County, northern California) Data collected on over 30 environmental variables Costello et al. ()Grapevine In 2011, 21 vines were positive out of 61 sampled In 2012, 43 vines were positive out of 61 sampled Grapevine growing provinces of Iran were visited, and plants exhibiting PD symptoms were sampled in 2011 and then in 2012. The samples were tested by DAS‐ELISA for infection by X. fastidiosa Amanifar et al.…”

“…• Costello et al (2017) evaluated incidence in Sonoma County (California): from 0.02% to 37.1%. Sonoma County has very hot summer.…”

Dating and localizing an invasion from post-introduction data and a coupled reaction–diffusion–absorption model

“…Indeed, winter temperature has been inferred as an important environmental factor governing the dynamics of Xf and the level of disease severity caused by Xf (Costello et al. 2017; Feil et al. 2003; Feil and Purcell 2001; Henneberger 2003; Purcell 1977; Purcell et al.…”

Pierce's Disease of Grapevines: A Review of Control Strategies and an Outline of an Epidemiological Model

“…In this study, Boisseranc identified high levels of soil dryness, soil sulfur content, vine calcium, and boron content as significantly reducing the predicted risk of PD. Recently, additional variables that negatively correlate to increased PD incidence have been pinpointed, of which cation exchange capacity and low soil pH appear to be the most significant (Costello et al, 2017 ). All the above-mentioned plant and field variables should be considered and potentially incorporated in the regular management of vineyards to control PD.…”