There has been a significant increase in number of samples that have tested positive for Fusarium graminearum this fall. Many are in areas where we have not seen Fusarium graminearum before, but most are also low level positives which can only be detected with the more sensitive PCR test. This provides an early warning of a low level or late-infection by the fungus. As long as seed still tests negative on a plate test it can be used, but a seed should treatment is strongly recommended.
Overall, 5.7% of the samples received to date have tested positive for Fusarium graminearum on plate tests with infection levels ranging from 0.5% to 10%.
Fusarium graminearum is very dependent on the weather. This year conditions were perfect during flowering — a warm and humid environment during flowering allows fusarium to infect plants quickly. Increased levels of infection this fall aren’t entirely surprising, however it’s still a serious situation.
Germination is affected by fusarium infection and can cause a decline or reduction in the final germination percentage. One or two seeds can quickly spread mycelium across a germination blotter making it almost impossible to read (see photo). Often laboratories will suggest retesting in soil to get a better interpretation of the seeds’ planting potential or recommend a seed treatment if the seed lot still has good germination and vigour.
To view a Wheat School episode highlight management of fusarium, click here.
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