HortScience (2001) 36, 934-936

David L. Ehret, Carol Koch, Jim Menzies, Peter Sholberg and Tim Garland (2001)
Foliar sprays of clay reduce the severity of powdery mildew on long English cucumber and wine grapes
HortScience 36 (5), 934-936
Abstract: Foliar sprays of a nonswelling chlorite mica clay were applied to leaves of greenhouse-grown long English cucumber (Cucumis sativus L.) plants, either before or after an artificial inoculation with powdery mildew [Sphaerotheca fuliginea (Schlech.:Fr.) Poll.] and to field-grown wine grapes (Vitis vinifera L.) before natural inoculation with powdery mildew [Uncinula necator (Schwein.) Burrill]. In all cases, the clay sprays did not eradicate the pathogen, but resulted in significant reductions in disease severity. In cucumber, a single spray of 0.5% clay reduced colony numbers on leaves by up to 60%. Spraying after inoculation was generally more effective than spraying before inoculation. In grapes, repeated sprays of either 2% or 4% clay were applied through the season to 'Reisling' and 'Chancellor' vines. Four percent clay reduced the amount of leaf surface covered by mildew by 22% in 'Reisling' and 51% in 'Chancellor'. Both concentrations reduced the incidence of mildew on clusters and canes. No treatment effects were observed on fruit quality. Our results demonstrate that foliar sprays of clay can reduce the severity of Sphaerotheca fuliginea and Uncinula necator on cucumbers and grapes, respectively.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): James G. Menzies

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Erysiphe necator	Grapevine (Vitis)
	Podosphaera fuliginea
	Podosphaera xanthii	Cucumber (Cucumis sativus)