Check for early signs of leaf disease

Check for early signs of leaf disease before your crop begins to tassel †

The past few seasons have led to an increased incidence of leaf diseases which can reduce yield ‐ sometimes dramatically.

  • Eyespot (Aureobasidium zeae) favours cool, wet and higher rainfall areas
  • Northern Corn Blight (Helminthosporium) favours warm and lower rainfall areas
  • Both diseases use airborne spores ‐ plus the maize crop’s own pollen - as a vector to infect the maize crop

Both the two main diseases in the UK can be controlled with either protectant or systemic based fungicides now available.†


When and why?

  • Early infestation (8 leaf stage onwards)
  • Symptoms only appear at a more advanced vegetative stage
  • Spores on contaminated leaves are spread by the wind
  • Cold temperatures
  • High air humidity

What to look for

  • Small, colourless, millimetre sized spots with brownish-red centre and yellow halos
  • Leaf blade dries out starting at the bottom. †By the end of the vegetation, the uppermost leaves and tips are the most affected

What to do and when

  • Choose varieties which are robust and suited to the region
  • Ensure stubble is finely chopped and incorporated into soil


  • The damage is caused by reduced photosynthesis of the plant
  • Can cause very significant losses

Northern Corn Leaf Blight (Helminthosporium turcicum)

When and why?

  • In mild to warm and humid areas, generally after flowering
  • Contaminated stubble of infested crops (resting spores, mycelia)
  • Ambient temperatures between 18-27įC
  • Humidity greater than 95 % e.g. dew, mist

What to look for

  • Spot-like lesions on lower leaves underneath the ear (primary infestation)
  • Appearance of spindle-shaped, oblong lesions parallel with the leaf veins
  • When lesions meet together, the leaf blade is destroyed (secondary infestation)
  • The plant finally withers depending on the weather and the amount of infectious material
  • Black dust on the stains = spores
  • High incidence

What to do

  • If the disease appears early and around 30% of the plants are affected, use a fungicide programme containing triazoles and/or strobilurins
  • Ensure crop rotation on already infested fields
  • Ensure stubble is finely chopped and incorporated into soil
  • Select tolerant varieties especially late maturing hybrids ‐ FAO 200+


  • May lead to very high yield losses in case of early infestation (3-4 weeks before silage maturity), as the plant prematurely finishes starch synthesis
  • Varieties with early maturity are usually more affected
  • It is not possible to assess the situation with just one check.† Effective control requires continuous monitoring of the disease

Cool start to spring 2016 points to earlier varieties across Northern Europe

KWS has seen rise in demand for earlier hybrids this season ‐ right across Northern Europe.

“Our sales development for Northern France, the Netherlands, Denmark, and the UK all indicate a shift to earlier maturity hybrids (typically from the more traditional FAO 220 ‐ 190, to FAO 170 ‐ 160 today… says UK sales manager John Morgan.

We see several clear reasons for this trend which has been developing more strongly since around 2012.

  • No negative yield loss compared to later hybrids from even 4 ‐ 5 years ago
  • Demand for higher silage quality ‐ earlier hybrids give a boost in ME (MJ/Kg) and starch content / tonne
  • More intensive maize cultivation for biogas plants wishing to stagger their harvest workload

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KWS Maize Demonstration Site

If you would like to visit the KWS Office and demonstration site at Lydney in Gloucestershire please contact your local merchant.

Demonstration field includes:

  • Breeding demonstration
  • All current commercial hybrids
  • Population wheel
  • First look at all new hybrids before they are listed
  • Chemical demonstration
  • AD trial which includes all our current and new hybrids

Also available adjacent to the demonstration field is:

  • Anaerobic digester
  • Dryer
  • Dairy unit

Farm Visit

If you would like us to visit your farm, please email the office at