Fungicides in Spring Cereals

Disease pressure in oats, barley and spring wheat can make for poor grain yield and quality. With the currently higher commodity prices and the strong demand for straw, there is a greater payback to fungicides on spring cereals. The application of a fungicide at the right crop stage impacts the effectiveness of fungicides to suppress disease pressure, whether it is leaf, stem or grain diseases.

Given the earlier planting of several spring cereal fields this year, growers should plan to scout their fields early to determine the cereal growth stage. Fungicide application timing will likely be two to three weeks earlier than normal.

Oats

In southern Ontario, oats need to have a fungicide applied at flag-leaf emergence stage for leaf diseases, such as crown rust. The genetic tolerance of most of the oat varieties to rust has broken down. Unless a fungicide is applied, the yield and quality loss from oat rust can be devastating (Figure 1). Leaf diseases are less frequently an issue in northern Ontario.

Figure 1. Flag Leaf Emerged Cereal Stage (Zadock 37)

Photo of Flag Leaf Emerged Cereal Stage.

The greatest yield response in oats is when the fungicides are applied at the "flag leaf emerged" stage (Zadock 37). This is when the last leaf emerges from the stem before the head emerges (Figure 2).

Figure 2. 2008 Fungicide Trial on Oats - Note lodging in unsprayed strips.

Photo of leaf emerging from the stem before head emerges.

In a 2008 oat fungicide trial in eastern Ontario, there was a 20% yield increase with the use of a fungicide on a variety where the genetic rust tolerance has broken down

Fusarium Head Blight (FHB)
For fusarium head blight (FHB) suppression in spring wheat and barley, the main fungicides are Prosaro and Caramba. The North Central Regional Committee on Management of Small Grain Diseases (NCERA-184) rated the fungicide efficacy for foliar diseases. The efficacy ratings of Prosaro and Carmaba for stripe rust, leaf rust, stem rust and FHB were the same.

Both products are most effective if applied at the correct growth stage.

  1. Prosaro
    Apply when at least 75% of the heads have emerged to 50% of the heads on the main stem are flowering.
  2. Caramba
    Apply when the cereal is at the 20% flowering stage (Figure 3 beginning of flowering).

Figure 3. Beginning of Flowering stage of a Wheat Head - note pollen sacks

Photo of a wheat head at the beginning of Flowering stage.

Proper nozzles must be used to maximize coverage and product efficacy for FHB suppression. The proper nozzle setup is the Turbo FloodJet. This setup has alternating forward and backward nozzles that target the fungicide on both sides of the cereal head (Figure 4). On-farm trials have shown a 4 - 8 bushel per acre grain yield advantage in spring wheat, and about 30 - 50% reduction in fusarium damaged kernels (%FDK).

Figure 4. Turbo Floodjet - alternating forward and backward nozzle set up for fungicide application for FHB suppression

Photo of a Turbo Floodjet with alternating forward and backward nozzle.

For more information about disease control management strategies and available fungicide products, refer to "A Field Guide to Cereal Staging", OMAFRA Publication 811, Agronomy Guide (p. 252) (www.omafra.gov.on.ca/english/crops/pub811/14cereal.htm) and Publication 812, Field Crop Protection Guide (p.52-81) (http://www.omafra.gov.on.ca/english/crops/pub812/p812toc.html).


For more information:
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E-mail: ag.info.omafra@ontario.ca