ISSUE 3    May 19, 2005


Recent rains may activate the tan spot fungus, and many winter wheat fields are in the appropriate stage for early season fungicide application. Fungicide treatment early season often is economical in winter wheat.

A cooperative fungicide trial on winter wheat cultivars was established on the Randy Mairs’ farm near Lisbon, ND from 2001-2004. Cooperators in the trial included Randy Mairs, Blake VanderVorst of Ducks Unlimited, the NDSU Extension Service, and several crop protection industries, including BASF, Bayer CropScience, and Syngenta.

Fungicide timings and rates of various fungicides were tested on winter wheat cultivars to evaluate efficacy against fungal leaf spots, leaf rust and Fusarium head scab. The primary strategies of application were to evaluate efficacy of: a single, early season fungicide (generally at half the full label rate), a combination of an early season application followed by a full rate of fungicide applied at full head emergence or early flowering, a single, full rate application at early flag leaf emergence, or a single, full rate application applied at full head emergence or early flowering.

Products tested at these timings included Headline, Tilt, Quilt, Stratego, or Folicur. Folicur was applied only at the full head emergence or flowering stage. Results, averaged over the four years, indicated that the combination treatment of an early season application followed by a late season application provided the greatest fungal leaf spot disease control and yield response. The single, flag leaf emergence treatment gave the least disease control and yield. (See table). A single, early season application generally was not as satisfactory as a combination treatment or late application, and data is not presented here.

Fungicide treatment strategy

Leaf spot
% reduction
over untreated

Leaf rust
% reduction over untreated

Head scab
% reduction  over untreated

% increase over untreated

Early + late

- 75.6

- 85.9

- 54.3


Flag leaf emergence

- 43.5

- 64.1

- 21.7



- 71.7

- 88.5

- 54.3


Of the 8 winter wheat cultivars tested over the 4 years, only CDC Falcon and Wesley were included all four years. CDC Falcon generally had the most fungal leaf spot disease when untreated (up to 35.5%), while Wesley generally had the highest head scab rating in the untreated (up to 21.9%).

Marcia McMullen
Extension Plant Pathologist

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