FEATURED INFORMATION

Integrated Management of Grapevine Powdery Mildew

Francesca Peduto Hand

Department of Plant Pathology, The Ohio State University

Grapevine powdery mildew caused by Erysiphe necator, the most common and economically important disease of grapevines worldwide, is the target of the majority of fungicides used in vineyards. Early infections can be cryptic, but once established, powdery mildew epidemics are characterized by exponential asexual reproduction via conidiospores and therefore are more easily prevented than eradicated. Hence, there is a tendency for prophylactic treatments against this obligate parasite.

A survey conducted in California indicated that over half of winegrape growers in the state use the UC Davis Powdery Mildew Risk Index (UC PMI, also known as Gubler-Thomas model) as a tool to time fungicide applications or to dictate what fungicide is applied.

Grapevine powdery mildew caused by Erysiphe necator, the most common and economically important disease of grapevines worldwide, is the target of the majority of fungicides used in vineyards. Early infections can be cryptic, but once established, powdery mildew epidemics are characterized by exponential asexual reproduction via conidiospores and therefore are more easily prevented than eradicated. Hence, there is a tendency for prophylactic treatments against this obligate parasite.

A survey conducted in California indicated that over half of winegrape growers in the state use the UC Davis Powdery Mildew Risk Index (UC PMI, also known as Gubler-Thomas model) as a tool to time fungicide applications or to dictate what fungicide is applied. Its use has been credited for improved control of powdery mildew and decreased use of fungicides. This model was derived from both laboratory and field trials and uses daily temperature averages to predict disease pressure after a rainfall/temperature event begins the disease cycle via ascospore release.

With global climate change, the need to understand the effects of high and low temperatures on pathogens and hosts has increased in importance. To this extent, we designed a systematic time course investigation to improve our understanding of the effects of high temperature on grape powdery mildew and how those data could inform disease management practices in vineyards. Our results underline the interactive effects of temperature and duration of exposure on E. necator’s ability to grow and reproduce. Our field data complemented our controlled environment data by taking into account factors that may be difficult to replicate in the lab (i.e. UV radiation, ontogenic resistance, diurnal temperature fluctuations).

After two years of testing revisions to the high temperature threshold of the UC PMI in the vineyard, we can conclude that the highest threshold evaluated (38°C x 2h) has the most potential to further reduce fungicide applications while providing adequate disease control.

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Data protection policy

In accordance with the Organic Law on the Protection of Personal Data 15/1999, of 13 December, Promotora de Exportaciones Catalanas SA (hereinafter PRODECA), whose address is Gran Via de les Corts Catalanes, 620, principal, 08007 Barcelona, with tax reg. no. NIF A58241316, declares that the images contained on the website www.smartfruitcongress.cat are included in a file belonging to PRODECA. The purpose of this file is the promotion, via its website, of the activities conducted by PRODECA – SmartfFruit IPM International Congress.

PRODECA guarantees that you may, at any time, exercise your right to access, rectify, cancel or oppose by writing to the aforesaid postal address, using the reference "PROTECCIÓN DE DATOS - SMARTFRUIT", or to the email address smartfruitcongress@smartfruitcongress.cat.

Specifically, to correctly exercise these rights you must clearly provide the following items in that communication:
- Name, surname(s) and photocopy of National Identity Document or Passport.
- Statement of the purpose of the request.
- Address for notification purposes.
PRODECA also declares that it reserves the right to delete from its website any content that it considers violates current and applicable legislation.

D’acord amb l’article 17.1 de la Llei 19/2014, la ©Generalitat de Catalunya permet la reutilització dels continguts i de les dades sempre que se'n citi la font i la data d'actualització i que no es desnaturalitzi la informació (article 8 de la Llei 37/2007) i també que no es contradigui amb una llicència específica.