Seedcare

Pathogens: Claciceps purpurea.

Affected crops: All cereals: Wheat, Barley, Oats, Rye and Triticale (also a wide range of grasses inc. Black-grass).​

Source of infection:

• Infection is spread by drilling the Ergots within the contaminated seed (1 of 2 diseases covered by the UK Seed Certification Scheme for Cereals).​
• Spread can occur from the overwintering spores from previous seasons.

Symptoms:

• The fungus only attacks the ear at flowering, replacing the grain in a few spikelets by a hard, purple-black sclerotium, known as an Ergot. ​

• Ergots can be very large, up to 2 cm in length, and are very obvious in the standing crop and in contaminated grain samples.

   

Importance​:

• The disease has very little direct effect on yield but the Ergots contain large amounts of toxic alkaloids.
• If grain contaminated with Ergots is fed to stock or used to make flour then there are real risks to animal and human health.
• Contaminated grain may be rejected.

Watch outs​: Cool, wet conditions during flowering (prolonged flowering period).

Pathogens: Ustilago spp (U. nuda f sp tritici, U. nuda f sp hordei and U. Avenae.

Affected crops: Wheat, Barley and Oats.

Source of infection: Fungus develops within plant as it develops and expressed in the ear.

Symptoms:

• At ear emergence grain is usually completely replaced by a mass of black fungal spores.
• Partly affected ears are sometimes seen​.
• ​The spores are released as soon as the ear emerges, leaving only the bare remains of the ear rachis.

Importance: Seed certification and resistant varieties have minimised seed-borne infection.

Watch outs:

• Cool, moist conditions during flowering​.
• Infected neighbouring crops.
• Seed repeatedly sown without treatment.

Pathogens: Tilletia tritici

Affected crops: Wheat

Source of infection: Infection can occur from either infected seed or soil.

Symptoms:

• No symptoms can be observed prior to ear emergence.
• In infected ears the grain is replaced by seed-like 'bunt balls' each containing millions of greasy, black foul smelling spores.
• The whole field may smell of rotting fish.
• In wet weather conditions the ears may appear to be covered in a black ink-like substance as the spores are released and run out of the protective glumes onto the ear and stem.

Importance: The disease is rare in the UK as the vast majority of seed is treated with a fungicidal seed treatment. However, the disease is potentially very damaging and can lead to complete crop loss due to grain being unsaleable because of discolouring and smell.

Watch outs:

• Each bunt ball contains millions of spores the capacity for contamination of healthy grain in the same field is enormous!​
• Continuous saving and resowing of untreated seed​.
• Contamination of machinery and stores​.
• Dry spores can survive years.​​