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Microdochium nivale
Microdochium seedling blight
General Description
Microdochium nivale and Microdochium majus can have a big impact on the emergence of crops
It is a seed-borne disease which affects winter sown cereals. Wheat is affected most, followed by oats then barley.
If seed is heavily contaminated with the fungus, and seed is sown in cold and wet conditions, the impact on germination can be severe.
Biology
The disease can contaminate the grain during the period up to harvest when conditions may be cool and wet.
Some fungicides applied to the head may reduce levels on the grain, but resistance to strobilruin fungicides is now widespread.
At harvest, seed may have high levels of contamination.
Seed sown in cold and wet seed-beds may be slow to emerge. These conditions are also ideal for the fungus to germinate and attack the seedlings.
This can have a major impact on crop establishment.
The two fungi responsible for causing Microdochium seedling blight in wheat and barley, Microdochium nivale and Microdochium majus, have become more prevalent over the last two years. Microdochium nivale and Microdochium majus are fungi which will colonise the heads of cereals in cool wet summers. These fungi are primarily a threat to winter wheat seed since they can reduce germination and cause a seedling blight in winter wheat. They are not known to produce mycotoxins, unlike other fungi known as Fusariums which can be present on cereals.
The Intstitut National de la Recherche Agronomique (INRA) ( French National Institute for Agricultural Research) have previously reported that these fungi may be resistance to the strobilurin fungicides in France. UK samples of these fungi have now been sent to INRA to be tested for resistance to strobilurin. This analysis has shown that strobilurin-resistance was detected in 16 of the 20 fungal samples from Scottish seed samples .
Farmers need to be aware of this development, so that they can modify late spraying programmes for wheat and barley. It is anticipated that strobilruin fungicides will have little impact on controlling the disease on the heads. Azole fungicides applied as head fungicides will still have some impact.
Advice
You should be aware that Fusarium (Microdochium nivale) is not covered by seed certification standards, and it can cause severe losses, particularly where seed is sown late in cold wet soils. A seed test will help you decide if a specific weed treatment is required. If you sow early in good conditions all seed treatments will provide effective control.