Table 1. Relative DON risk assessment indices by hybrid relative to high-checks (not shown) from 2022-2025

Table 1: Harriston, Dundalk

Table may be sorted on any column by clicking the column headings. A second click sorts in reverse order. Hold down the Shift key to sort on multiple columns.

Hybrids are initially sorted by CHU rating. Indices are not DON (ppm). Always interpret one-year data with caution, as environmental effects can be large. It is best to use multi-year data. Always use one-year data with caution. Several hybrids were entered by companies in 2022 and 2024, but not in 2023, hence the "2022, 2024-25 not 2023" column.

The colour scheme highlights relative hybrid effects within column. Indices = relative to the mean of the high checks within column (example, index 100 = same DON as high checks, index 50 = 1/2 DON as high checks).

"H" = hybrid not sig different than the high checks (P=0.05)

"M" = hybrid sig lower DON than high checks, but still sig higher than low checks (P=0.05)

"L" = hybrid DON similar to the low checks (P=0.05)

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Table 2. Relative DON risk assessment indices by hybrid and environments in 2025

Table 1: Harriston, Dundalk

Table may be sorted on any column by clicking the column headings. A second click sorts in reverse order. Hold down the Shift key to sort on multiple columns.

Hybrids are initially sorted by CHU rating. Indices are relative to high-checks. They are not ppm. Always interpret one-year data with caution, as environmental effects can be large, as observed in this table across environments. It is best to use multi-year data from Table 1.

The colour scheme highlights relative hybrid effects within column. Indices = relative to the mean of the high checks within column (example, index 100 = same DON as high checks, index 50 = 1/2 DON as high checks).

"H" = hybrid not sig different than the high checks, pooled across environments (P=0.05)

"M" = hybrid sig lower DON than high checks, but still sig higher than low checks, pooled (P=0.05)

"L" = hybrid DON similar to the low checks, pooled across environments (P=0.05)

Interpretation of DON levels across environments -- note the DON across the high-checks.

In 2025, DON in the high-check hybrids was highest in the early-planted environments (Env 1 Exeter: 14.2 ppm; Env 3 Ridgetown: 31.2 ppm) and lowest in the later environments, especially Env 5 (2.0 ppm). Growth of Fusarium graminearum after silk inoculation is strongly temperature dependent, with optimal growth near ~28 C and reduced growth under cooler or hotter conditions. Earlier silking in Env 1 and Env 3 probably aligned with more favourable temperatures post-silking, resulting in higher DON, whereas later environments constrained fungal growth. In contrast, the relatively low DON in the high checks in Env 5 inflated relative hybrid indices, which reflects more about high variability at low DON concentrations rather than elevated DON expression in some hybrids.

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