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There’s a whole range of seed and soil-borne fungal diseases that can attack and hold back cereal establishment and severely impact yield and quality – many of which worsen with later sowing.

For years, these diseases have been kept at bay because fungicide seed treatments have been routinely used. Neonicotinoid seed treatments (no longer available) were also routinely applied with a fungicide seed treatment. It is important not to let this control slip.

Know your risk

Even if planting ‘clean’ tested seed, remember that several of these diseases can also attack from the soil.

Diseases:

Start by re-familiarising yourself with the various seed and soil-borne pathogens and their potential impact: 

Wheat pathogen

Source of infection

Risk factors

Impact

Microdochium seedling blightA

M. nivale and majus

  • Seed
  • Soil
  • Infected seed
  • Poor seedbeds
  • Late drilling
  • Loss of plants – poor establishment
  • Reduced yield

Fusarium blightA

F. graminearum

  • Crop debris
  • Seed
  • Maize in rotation
  • Infected seed
  • Poor seedbeds
  • Loss of plants – poor establishment
  • Reduced yield

BuntA

Tilletia tritici

  • Seed
  • Soil
  • Wind
  • Infected seed
  • Late drilling
  • Short time between harvest & drilling
  • Quality
  • Infected grain smells of rotting fish
  • Infected grain is rejected

Septoria seedling blightA

Phaeosphaeria nodorum

  • Crop debris
  • Seed
  • Infected seed
  • Cool wet soil
  • Late drilling
  • Loss of plants – poor establishment
  • Reduced yield

ErgotS

Claviceps purpurea

  • Seed
  • Wind
  • Black-grass contamination
  • Cool wet conditions at flowering
  • Yield is minimally affected
  • Ergot is highly poisonous to humans and animals
  • Contaminated grain will be rejected or require cleaning

Loose smutS

Ustilago tritici

  • Seed
  • Wind
  • Infected seeds
  • Cool wet conditions
  • Other infected crops
  • Ear replaced by black fungal spores
  • Loss of yield
  • Crop rejection (quality)

Foot rotA

Cochliobolus sativus

  • Soil
  • Seed
  • Warm, damp weather
  • Plant loss and slow growth
  • Not often a problem in the UK

Barley pathogen

Source of infection

Risk factors

Impact

Loose smutS

Ustilago tritici

  • Seed
  • Wind
  • Infected seeds
  • Cool wet conditions
  • Other infected crops
  • Ear replaced by black fungal spores
  • Loss of yield & quality

Leaf stripeA

Pyrenophora graminea

  • Seed
  • Wind
  • Infected seed
  • Cold, over compacted or waterlogged seedbeds
  • Other infected crops
  • Most serious of seed-borne diseases in barley
  • Relatively rare in the UK but potentially serious when seen with significant yield loss
  • Reduction in grain quality

Seedling blightsA

Microdochium nivale & F. graminearum

  • Seed
  • Soil
  • Infected seed
  • Poor seedbeds
  • Late drilling
  • Loss of plants – poor establishment
  • Reduced yield

ErgotS

Claviceps purpurea

  • Seed
  • Wind
  • Black-grass contamination
  • Cool wet conditions at flowering
  • Yield is minimally affected
  • Ergot is highly poisonous to humans and animals
  • Contaminated grain will be rejected or require cleaning

S: Statutory Regulatory threshold – check the maximum legal levels before choosing a treatment option

A: Advisory Regulatory threshold – check the maximum threshold levels before choosing a treatment option

Disease symptoms:

Fusarium sp. & Microdochium

• Plant loss
• Stem based browning
• Weaker tillers
• Establishment loss is the most important phase of M.nivale
• Later in their life cycle they can cause foot rots and ear blights and can significantly reduce yield

Bunt

• 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

Ergot

• 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

Loose smut

• 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

Leaf stripe

• Leaf stripe can affect the plant in 3 ways:
• It can kill seedlings as they emerge (unusual but can occur if soil conditions are very poor)
• It can reduce the efficiency of the plant by reducing green leaf area
• It can result in complete blindness of the ear resulting in no harvestable grain from affected tillers