Efficacy of fungicides with various modes of action in controlling the early stages of an Erysiphe necator-induced epidemic.
BACKGROUND
Limiting the use of fungicides is due to become an important issue in managing Erysiphe necator (Schwein) Burrill infections in vineyards. The authors determined how three fungicides currently used by vine growers could be managed to control the early stages of an E. necator-induced epidemic.


RESULTS
Leaf-disc bioassays and field experiments suggested that the protectant quinoxyfen induced minor disruption in E. necator development, but compounds with protectant and curative properties (tebuconazole and trifloxystrobin) caused significant, although different, disruption during E. necator-induced epidemics. Bioassays showed that each of the antifungals were most effective at different stages of fungal development, tebuconazole before sporulation and trifloxystrobin after sporulation of the colonies. Results from the bioassay also highlighted likely occurrences in the field, where several stages of fungal development are encountered simultaneously.


CONCLUSIONS
The present findings were complementary: leaf-disc tests showed when the fungicides were most effective at inhibiting E. necator infection cycles; the field trial provided results in terms of incidence and severity of disease on bunches without reference to the pathogenic cycle development. A protection strategy combining the different types of fungicide under study is suggested.
UMR en Santé Végétale 1065 INRA/ENITAB, Institut des Sciences de la Vigne et du Vin, INRA Domaine de la Grande Ferrade-BP81, Villenave d'Ornon Cedex, France.
Laurent
L
Deliere
Anne Sophie
AS
Miclot
Pierre
P
Sauris
Patrice
P
Rey
Agnès
A
Calonnec
D001203:Ascomycota / Q000187:drug effects* / Q000254:growth & development*; D058872:Epidemics; D005659:Fungicides, Industrial / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology*; D011804:Quinolines / Q000494:pharmacology; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development; D027843:Vitis / Q000382:microbiology*
D005659:Fungicides, Industrial; D011804:Quinolines; C470613:quinoxyfen