Infection ‘not as bad as was first feared’

Incidences of infection in this year’s maize crop are less widespread than at first feared, says Dr Pope, but where disease took hold, yield losses of up to 80 per cent were reported.

“Eyespot has been a significant problem for growers in the south west of England but it is slowly spreading across southern England and into South Wales,” he says.

“Carmarthenshire and Pembrokeshire have become real hotspots for the disease with growers reporting significant yield losses.

“Despite a very wet summer, we have seen fewer cases of infection than anticipated. This is largely a reflection of the growing season which has been warmer than average, preventing extensive disease taking hold.”

Eyespot catalyst

Caused by the fungus kabatiella zeae, eyespot produces stroma which over-winter in maize debris and germinate in the spring to produce conidia, which are wind and rain dispersed.

“It is therefore important to bury the trash as quickly as possible to prevent the re-infection of following crops,” says Dr Pope.

“Deep ploughing gives the best results because it prevents sporulation and causes the fungal stroma to rot in the ground. Shallow cultivation techniques are less effective at controlling the condition and any surviving stroma will germinate as soon as the temperature reaches 10degC in the spring.”

Maize plants are at their most susceptible to infection at 10-12degC and conidial germination on the leaf requires seven hours of continual leaf wetness.

“That is why cold, wet seasons provide ideal conditions for the spread of the disease,” says Dr Pope. He recommends considering this when selecting varieties.

“Maize crops grown under plastic also seem to have been less affected by the disease, as they can be harvested earlier than conventionally-grown crops, so are not exposed to the disease for as long.

“Therefore, the effects can be less pronounced and there is less risk of yield implications.”

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